HVAC and plumbing supply house software in Baltimore: Maryland now checks who is buying the furnace, and the EPA gave the R-410A in the warehouse a reprieve

Picture three businesses in the Baltimore area’s supply trade with a busy heating season ahead. The first is a family-owned heating, cooling and refrigeration distributor off Pulaski Highway in Baltimore County, with two branches, about 1,500 contractor accounts and a counter that opens before six. On the first Saturday in October 2025, a homeowner asked to buy a ductless mini-split, and for the first time the counter had a legal question to answer: Maryland had just made it unlawful to knowingly sell heating and cooling equipment to anyone who is not licensed, does not employ a licensee, does not resell to licensees and is not exempt, and it now requires a written notice with every sale. The answer was yes, as it happens, if the buyer owned the single-family house the unit was for and meant to install it personally. The same distributor still has a few dozen R-410A condensing units built in 2024. From January 1 to July 26 of this year, none of them could legally become part of a new system. Since July 27 they can again, but only if every coil they are paired with was also made or imported before 2025, and only if the unit itself was in the country by then.

The second is a plumbing and hydronic heating supply house in the City, selling copper, PEX, brass, water heaters and boilers to plumbers. Its heating and cooling equipment is a small share of its revenue, which may put it outside Maryland’s new buyer check but not outside the notice. Its exposure is a federal rule most of its customers have never read: since September 2023, the pipes, fittings and fixtures it sells for drinking water must, with narrow exceptions, come certified lead free by a third party, solder that is not lead free may not be sold by a supply house at all, and the exemption for brass valves meant for gas or refrigerant depends partly on how they are marketed, which on the internet means the category page.

The third is a contractor who wants to sell refrigerant, tools and do-it-yourself mini-splits online from a small warehouse in Halethorpe. Federal law lets almost anyone buy the pre-charged mini-split, exempt as equipment and, as a kit, covered by a stay the EPA issued in 1995 and has never lifted, but lets only a certified technician buy the refrigerant to top it up, and the online seller must check the certificate and keep the invoice for three years. Amazon, eBay and Walmart will not list the refrigerant at all. Google’s checkout inside its AI search results excludes items that need freight or installation, and in Maryland the mini-split itself is now restricted equipment.

Each of them has a software problem dressed as a compliance problem. The rules now ask who is buying, under which license or exemption, with which refrigerant certificate; which unit is which, by serial number, date of manufacture and date of entry; whether a job is a new system or a repair, and what it replaces; which pairing of outdoor and indoor units the rating and the rebate belong to; and whether a fitting is certified lead free or merely filed under “water.” Every one of those questions is answered by the way a supply house keeps its accounts, its inventory and its order lines, and the answers have to exist before a regulator, a utility or a customer asks. This article goes through those questions for Baltimore City and Baltimore County, using the federal regulations and their preambles, Maryland’s statutes and regulations, BGE’s program documents, Census and ENERGY STAR data, a look at how the 26 supply-house locations in Baltimore City and Baltimore County and 14 national online sellers of refrigerant and HVAC equipment show up online, and it sets out what the software costs. It covers the online store in detail, because that is where the counter’s questions have to be asked without a person behind the counter. It is our reading of the rules for the products we build, not legal advice.

What Baltimore’s supply trade looks like

One of the largest heating and cooling distributors on the East Coast started in a Baltimore rowhouse. According to its own history, R.E. Michel Company was founded in 1935 in the 1000 block of Greenmount Avenue; its branch locator still lists a store at 1030 Greenmount, and the company now describes itself as having more than 300 locations, run from Glen Burnie. That is the trade in miniature: old, local, built on the counter and the contractor relationship, and by now mostly organized into regional and national networks whose branches sit along the industrial corridors around the city.

The Census Bureau’s County Business Patterns, which counts establishments with paid employees, gives the shape. In 2023, Baltimore City had 11 establishments classified as plumbing and hydronic heating wholesalers or warm-air heating and air-conditioning wholesalers, with about 60 employees between them; its refrigeration-equipment wholesalers were too few to publish. Baltimore County had 48 across the three industries, with 981 employees, and its plumbing and heating wholesalers averaged 27.5 employees each against 2.4 in the City. Statewide there were 294, with 3,843 employees. The County is where the warehouses are, along Pulaski Highway, around Golden Ring and on Hollins Ferry Road, which also illustrates a small data trap: three distributors on Hollins Ferry Road in ZIP code 21227 give their addresses as Baltimore, Lansdowne and Halethorpe, and all three are in Baltimore County, not the City. A branch table that stores only the mailing city will get the jurisdiction wrong. These are also the newest county figures there will be for some time: the 2024 county file is not on the Census server, and the Bureau’s methodology page now says that its information “is no longer current” while the Bureau evaluates how to comply with a Commerce Department order “prohibiting the use of noise infusion,” the technique it used to protect the data.

Who sells online, and how much

Supply houses sell online less than wholesalers in general, but the leaders are far ahead of the average. In the Census Bureau’s Annual Integrated Economic Survey for 2024, released in September 2026, hardware, plumbing and heating merchant wholesalers made 24.4% of their sales electronically, against 35.1% for all merchant wholesalers, both figures counting orders over electronic data interchange as well as the web. Watsco, the largest distributor of heating and cooling equipment in North America, reported $2.7 billion of e-commerce sales in the twelve months to June 30, 2026, 37% of its sales, with its best regions above 70%, and told investors it has spent more than $250 million on its digital platforms over five years. Lennox, which sells its own equipment to dealers through about 250 company stores, told investors in March that about half of its residential sales are now digital, excluding EDI, and that its dealer site suggests matched systems by AHRI rating. When we checked on October 21, the Lennox dealer site also carried a notice about Maryland’s new law on equipment sales on its home page, the only distributor site we found that did.

The pressure behind those numbers is regulatory as much as commercial. Watsco described the 2025 switch to A2L refrigerants as “the second such regulatory-driven product change in three years,” affecting about 55% of the products it sold and requiring it to convert more than $1 billion of inventory and add more than 10,000 product records, complete with what it called “regulatory match-ups.” The new refrigerant was rationed for much of 2025: distributors capped cylinders per invoice, sold only to existing refrigerant customers or only with an outdoor unit on the same order, Honeywell added a 42% surcharge, and trade press reported cylinders near $900 in the summer, before an official of the distributors’ association, HARDI, declared the shortage over in October. Meanwhile the product mix keeps moving toward electricity. The Air-Conditioning, Heating, and Refrigeration Institute’s shipment data show 3,644,596 heat pumps shipped in the United States in 2025 against 3,247,426 gas furnaces, and heat pumps were 47% of central air conditioner and heat pump shipments; through August 2026, heat pump shipments were up 5.7% and furnace shipments down 5.0%. And plumbing and heating distribution are converging: in September, Watsco agreed to buy the Granite Group, a plumbing and HVAC distributor in the Northeast, for $505 million.

For an independent Baltimore supply house, the comparison that matters is not with Amazon. It is with the chains’ contractor apps, which already carry the matched systems, the account pricing and, increasingly, the compliance rules, on budgets no independent can match. The rest of this article is about which of those rules an independent must encode anyway, and how little of it general-purpose software does.

What supply-house software costs, and what the meter counts

A supply house runs on its ERP, the distribution system that holds branches, inventory, purchasing, pricing matrices, counter tickets and receivables, and most of the ones this trade uses come with an online store module of their own. None of them publishes what it costs. On October 21 we checked the vendors’ own pages for Epicor Eclipse, Epicor Prophet 21 and its e-commerce module, Infor CloudSuite Distribution, DDI System Inform and its Commerce Vision store, Oracle NetSuite and SAP Business One. Every one asks for a conversation. Several of their pricing and product pages are simply gone: NetSuite’s pricing page returns “Page Not Found,” SAP’s Business One pricing page and Infor’s SX.e page return 404, and DDI’s old domain now redirects to its new owner, Advantive.

A few systems that distributors also use do publish. Microsoft Dynamics 365 Business Central lists $80 per user per month for Essentials, $110 for Premium and $8 for a limited Team Members seat, paid yearly. Acumatica prices a bundled package called APEX for Distribution, software, implementation and support together, at “a starting price under USD 1,495 monthly,” and its product sheet describes a single warehouse and no online store. Odoo and QuickBooks Enterprise publish too, but neither is what a two-branch heating and plumbing distributor typically runs.

The online store’s meter is the price list, not the plan

For a business-to-business store, the decisive feature is account-specific pricing, because a supply house quotes each contractor off its own matrix. That is exactly where the general-purpose platforms put their dividing line. Shopify’s B2B features now run on every plan, but “on the Basic, Grow, and Advanced plans, you can assign up to 3 active catalogs across all your B2B markets”; unlimited catalogs require Shopify Plus, which starts at $2,300 a month on a three-year term or $2,500 on a one-year term, while “more complex, higher volume businesses” switch to a variable platform fee that Shopify does not publish. Shopify’s payment terms are a fixed menu, “Net 7, Net 15, Net 30, Net 45, Net 60, Net 90, or due on fulfillment,” so the term many supply-house statements still carry, payment by the tenth of the following month, has to be approximated. Deposits on orders placed on terms are a Plus-only feature.

BigCommerce rebuilt its plans on June 1, 2026. Customer price lists are now on its Performance plan only, from $1,499 a month billed annually, and a store moves to Performance automatically once its online sales pass $2 million over the trailing twelve months; the plan below it, Scale, at $299 a month billed annually, adds 0.9% on monthly sales above $33,333. The plugins that bolt wholesale pricing onto WooCommerce are cheap, B2BKing at $199 to $449 a year and Wholesale Suite at $299 a year, both at discounted prices when we checked, and the B2B apps for Shopify’s lower plans run from free to $499 a month and more, with order caps on the smaller tiers. Adobe Commerce, Optimizely Configured Commerce, OroCommerce, Sana and Unilog quote.

The data, the tax and the card

Three other meters matter more than the store. The first is product data. AHRI licenses its directory of certified ratings, the data a matched-system tool and a utility discount both depend on, and its 2027 fee schedule, released in July, charges $15,904 a year for the unitary package, or $4,123 a year for licensees such as a HARDI distributor that uses the data in tools but “does not require payment for someone to receive, access, or utilize such tools.” An API costs $3,740 a year more, plus $1,200 to set up. One clause matters to anyone hiring a developer: “An organization hired by, or on behalf of, the Licensee … to provide or support tools is not eligible for the discounted fee,” so the supply house should hold the license itself.

The second is sales tax. Avalara’s Core Compliance plan for companies under $50 million in revenue costs $799 per state per year. Shopify Tax charges per order instead, 0.25% on Plus up to $0.99 an order, and for stores created since May 13, 2026, after the first $100,000 of lifetime sales and with no annual cap. The third is the card. A supply house that moves $9.8 million of orders online and takes 30% of it by card pays more in processing than in all its software subscriptions combined. Maryland’s Commercial Law has a provision, §12-509, that permits a seller to offer “a cash discount to consumers who pay cash,” and we found no Maryland statute that caps or bans card surcharges, but Visa’s rules cap a surcharge at the merchant’s cost of acceptance and 3%, Mastercard’s at 4%, and neither allows surcharging debit cards, so a checkout that surcharges has to tell credit from debit first.

The arithmetic behind the table is simple, and it makes one point. Online orders of $9.8 million at an average of $350 are 28,000 orders a year; card payments on 30% of them are $2.94 million; at Shopify Plus’s standard rate of 2.25% plus 30 cents, that is $66,150 plus $2,520 in per-order fees. Every priced stack in the table costs less to subscribe to than to accept cards on, and the cheapest subscription is not the cheapest system if its catalog limit forces a supply house to price 1,500 accounts through three lists. Connecting to large customers’ purchasing systems by punch-out is priced for bigger distributors than most Baltimore independents: TradeCentric, formerly PunchOut2Go, says suppliers with $100 million to $1 billion in revenue typically start at $15,000 to $50,000 a year, usually on a three-year minimum.

Since October 2025, Maryland regulates the buyer as well as the installer

For as long as there have been supply houses, the counter has sold to whoever had an account, a card or cash. Maryland licensed the people who install heating and cooling systems, through the State Board of Heating, Ventilation, Air-Conditioning, and Refrigeration Contractors under Title 9A of the Business Regulation Article, but it never told the counter whom it could sell a furnace to. That changed on October 1, 2025. Chapter 386 of 2025, which began as House Bill 1162, added a new section, §9A-501.1, and its central sentence is short:

“A person may not knowingly sell or offer to sell heating, ventilation, air–conditioning, or refrigeration equipment to another person, unless the individual purchasing the equipment: (i) holds a master license, a master restricted license, or a limited license or employs an individual who holds a master license, a master restricted license, or a limited license issued by the Board to provide or assist in providing heating, ventilation, air–conditioning, or refrigeration services; (ii) operates a business that resells heating, ventilation, air–conditioning, or refrigeration equipment to individuals licensed by the Board; or (iii) is not required to be licensed under § 9A–103 of this title.”

The penalty, added to §9A-505, is a civil fine of up to $1,000 for a first violation and up to $5,000 for each one after that. The Department of Legislative Services, in its fiscal and policy note, put the consequence plainly: small businesses that buy HVACR equipment without holding or employing a license “may be unable to purchase HVACR equipment” unless an exemption covers them.

Who may buy, and the license that is missing from the list

Three kinds of license qualify a buyer: a master license, a master restricted license, which covers only one of heating by forced air, hydronic heating, ventilation, air conditioning or refrigeration, and a limited license, which is issued only to maintain or repair systems. A journeyman license does not appear in the sentence. A journeyman works under the direction of a licensed contractor, and the statute assumes that the purchase goes through that contractor’s account. In practice that turns a familiar counter scene into a question: the journeyman who comes in on a Saturday to buy a condenser for a side job, on a personal card, is not buying for an employer who holds the license, and nothing in the list covers that sale.

The third route is the broadest, because it imports the whole list of people Title 9A has never required to be licensed. Section 9A-103 has ten entries, and each of them is now, in effect, a class of customer:

Read as a data model, the table says something the old account application never had to: the permission to buy is not a property of the customer alone. It depends on the customer, the product and the job. A master plumber may buy a boiler for a hydronic system and not a heat pump. A homeowner may buy a mini-split for a house they own, which is why the law does not end do-it-yourself installation in Maryland, and a tenant in the same house may not. A building’s maintenance employee may buy a replacement motor for the owner’s rooftop unit, and so on. One of the routes qualifies a product rather than a person: a 115-volt window unit is outside Title 9A whoever installs it.

A notice at every sale, with text nobody has written

The second half of the section applies to every sale, whoever the buyer is. Under §9A-501.1(b), a person that sells HVACR equipment “shall, at the time of sale, provide a written notice to the individual purchasing the equipment that contains information prescribed by the Board regarding the requirement that an individual be licensed by the Board before providing or assisting in providing heating, ventilation, air–conditioning, or refrigeration services in the State, including the installation of heating, ventilation, air–conditioning, or refrigeration equipment.” The statute gave the Board until January 1, 2026, to adopt regulations. It adopted one, COMAR 09.15.02.11, effective March 2, 2026, and it says two things: that the Board “may seek regulatory action against an individual who violates” the section, and that such cases proceed under the Board’s ordinary hearing procedure in §9A-311. It does not say what the notice must contain, and the Board has not published a template. Its minutes record that “a notice was sent to all HVACR licensees shortly after the law went into effect on October 1,” and that the contractors’ association, HACC, “distributed a similar notice to its supplier network,” but neither text is on the Board’s website. The same minutes are the closest thing to guidance a supply house has: at the November 2025 meeting, the Board’s counsel said that window units and other self-contained appliances are excluded, a Board member said that tubing on its own is not equipment, and the minutes record that licensed journeymen and apprentices “may be sent by their employer to a supply house to purchase or pick up materials.” In December, answering Carrier Enterprise, which has five Maryland locations, counsel said that materials shipped outside Maryland are outside the Board’s jurisdiction, but that a buyer providing services in Maryland must still have a licensed person in the company. In January 2026, Northeastern Supply wrote to the Board describing how suppliers had begun putting the requirements into practice.

For software, the notice is the easy half and the one most likely to be skipped. It belongs on every invoice, every will-call ticket and every online order confirmation that contains equipment, in the same words each time, with a record that it was given. Because it must be given “at the time of sale,” an emailed confirmation sent after a counter sale is the weaker version; a line printed on the ticket the customer signs, and shown before the online order is placed, is the stronger one.

What the General Assembly took out

The bill as introduced went further, and the chapter as printed still shows the struck text. It would have required a seller to “collect the name and license number of an individual who purchases” HVACR equipment at the time of sale, to give the written notice only when it could not collect them, and, for any business with $100,000 or more a year in HVACR equipment sales, to file a report with the Board after each fiscal year listing “the name and license number of each individual” who had bought from it. All three were amended out before passage. What survived is a prohibition with a knowledge standard and a notice requirement, and no recordkeeping rule at all.

That combination is worth pausing on, because it is the opposite of the federal refrigerant rule, which, as the next section shows, spells out exactly which invoice fields to keep for three years. Maryland’s law punishes knowingly selling to the wrong person and says nothing about records, which leaves a seller’s own records as the only evidence of what it knew. A supply house that keeps a verified license number, or a stated exemption, on every account and every invoice can show that it did not sell knowingly to an unqualified buyer. One that keeps nothing has to argue it.

The exemption is a revenue test, and “equipment” is not defined

The prohibition in subsection (a) does not apply to a seller that both “sells construction materials other than materials involved in the installation of” HVACR equipment and “derives less than 25% of the person’s revenues” from selling HVACR equipment. That is the home center’s exemption, and on our reading it means a buyer without a license, homeowner or not, can still buy a furnace at a big-box store, which must hand over the notice but need not ask any questions. The Board’s executive director told the Board in November 2025 that “large retailers would also fall under the requirements,” which is plainly true of the notice and, as we read subsection (a)(1), not of the buyer check. The exemption also creates a less obvious case. A plumbing-led supply house that sells mostly pipe, fixtures and water heaters, with HVACR equipment below a quarter of its revenue, may fall under the same exemption, while a supply house down the road that sells mainly heating and cooling equipment does not. Whether the buyer check applies depends on a figure in the general ledger, the company’s revenue mix, rather than on anything at the counter.

Then there is the word itself. Title 9A defines a cooling system, a heating system, a hydronic system, a refrigeration system and a ventilation system, and the services that may be provided on them. It does not define “equipment,” and neither does the Board’s regulation. At the November 2025 meeting a Board member said the term was already defined in COMAR 09.15.01.02, and counsel agreed, but that regulation, as published, defines four terms, and “HVACR equipment” is not one of them. A condensing unit, a furnace and an air handler are surely equipment. A replacement blower motor, a capacitor, a thermostat, a line set, a bag of fittings or a 25-pound cylinder of refrigerant may or may not be, and a supply house has to decide, product class by product class, where the line falls. We would draw it conservatively and record the decision on the product, so that the rule the counter applies, the rule the website applies and the rule a manager can defend are the same rule.

On the same invoice, a tax rule that ignores the contract

The buyer’s status also decides the tax line, and here Maryland is old and precise. A contractor who installs equipment in a building is the consumer of it, not a reseller: under COMAR 03.06.01.19, a person who “constructs, improves, alters, or repairs real property shall pay the tax on all materials purchased” that become part of it, and “taxability is not affected by language in a real property construction contract or subcontract such as ‘tax included’ or ‘tax exempt’.” So the 6% is collected at the counter, from the contractor, whatever the contractor’s customer is. There is one exception and one trap. A contractor working for a Maryland nonprofit charitable, educational or religious organization, a volunteer fire, ambulance or rescue company, or a veterans’ organization may use that organization’s exemption certificate, with a signed statement naming the organization, its certificate number and “the date and identification of the contract.” A contractor working for the State, a county, the City or the federal government may not use the government’s certificate at all. The Comptroller numbers exemption certificates by category, 29 for religious institutions, 30 for governments, 31 for educational and charitable organizations, 32 for credit unions, 33 for volunteer fire and rescue companies and 34 for veterans’ organizations, so a checkout can tell from the first two digits whether a contractor may use the certificate in front of it. Resale certificates are a separate path, for buyers who resell the goods as personal property, and they too carry a Maryland registration number of a fixed form: eight digits, the first a zero or a one.

What the counter, and the cart, now have to know

Put together, the Maryland section turns the account record into a compliance record. Each account needs its qualifying route: a license number with its type and expiry, checked against the State’s license search, or a reseller status, or one of the §9A-103 exemptions with what the buyer stated about it. Each account needs a list of the people authorized to buy on it. Each product needs a flag saying whether it is HVACR equipment, and the electrical rating that takes a self-contained appliance out of scope. Each sale needs the notice, printed or shown, and stored. Checking the license is a manual step. The Maryland Department of Labor’s public license search shows active licensees only, with each license’s category, expiration date and insurance status, but the search by name sits behind a CAPTCHA, so it cannot simply be queried by software, and expiration dates are staggered, so the account has to store the real date rather than compute one. The Board counted 25,062 active licensees in June 2026.

The online store raises the stakes, because the statute covers offering to sell as well as selling. A public catalog that lets any visitor in Maryland put a condensing unit in a cart and pay for it is the situation the words “offer to sell” seem written for. That does not mean prices must disappear behind a login. It means the step that turns a visitor into a buyer of equipment, account creation or checkout, has to ask the questions the counter asks, and keep the answers.

Refrigerant is sold to a certificate, not to an account

The federal rule on who may buy refrigerant is older than Maryland’s rule on equipment, and much more specific. It sits in the Environmental Protection Agency’s regulations under section 608 of the Clean Air Act, at 40 CFR 82.154(c), and it covers ozone-depleting refrigerants such as R-22 and, since January 1, 2018, their non-exempt substitutes, which is to say the hydrofluorocarbons that fill today’s cylinders: R-410A, R-134a, R-404A, and the newer R-32 and R-454B. Paragraph (c)(1) reads like an access-control list:

“No person may sell or distribute, or offer for sale or distribution, any substance that consists in whole or in part of a class I or class II substance or, starting on January 1, 2018, any non-exempt substitute for use as a refrigerant unless: (i) The buyer has been certified as a Type I, Type II, Type III, or Universal technician under § 82.161; (ii) The buyer employs at least one technician who is certified as a Type I, Type II, Type III, or Universal technician under § 82.161 and provides proof of such to the seller …”

The rest of the paragraph adds the other permitted sales: to technicians certified under section 609 for motor vehicle air conditioning, if the refrigerant is acceptable for cars; for resale to certified technicians or appliance manufacturers; to an appliance manufacturer; refrigerant charged into equipment by a certified technician during service; and small cans of car refrigerant, two pounds or less with a unique fitting and, since 2018, a self-sealing valve, which anyone may buy. It also exempts refrigerant “contained in an appliance with a fully assembled refrigerant circuit or an appliance component,” which takes the equipment itself out of the rule, a point we come back to below.

What the seller must check, and what it must keep

The EPA’s questions and answers on the sales restriction, last updated on September 15, 2026, put the burden in one place: “The seller of the refrigerant is responsible for verifying that the buyer either 1) is a certified technician, or 2) employs a certified technician.” Where more than one company is involved, for example one handling sales and another the distribution, “all sellers and distributors are responsible for verifying a technician’s certification.” That sentence matters for any supply house that ships through a marketplace, a buying group or a third-party warehouse. The verification cannot be left to the other party’s checkout.

The records are specified in the regulation. Under 82.154(c)(3), a seller keeps “invoices that indicate the name of the purchaser, the date of sale, and the quantity of refrigerant purchased,” and, where the buyer qualifies by employing a certified technician, “the documentation provided by the buyer to demonstrate such employment,” all for three years. The EPA adds that the invoice “does not need to include the technician’s certification number,” partly because some section 609 cards have none. The EPA’s answer for technicians puts it in account terms: “The purchasing account holder is the buyer, and anyone purchasing refrigerant under that account is allowed to conduct the transaction, provided that the account holder can demonstrate they are a certified technician or currently employ a certified technician.” An office manager may buy on the company’s account if the company provides evidence such as “a copy of the certification card and a list of those authorized to buy refrigerant or accept delivery of refrigerant,” and a driver may leave refrigerant at an unattended site if the wholesaler knows it will be received by the purchaser or an authorized representative.

None of that changes online. The agency’s answer on internet sales is direct: “The online sale of refrigerant is subject to the same recordkeeping and technician certification verification requirements as in-person refrigerant sales.” A product page that says only certified technicians may buy “can minimize the chance that an unqualified person will attempt to purchase the refrigerant,” it adds, but “the online vender must still verify, and maintain documentation indicating that the purchaser is or employs a certified technician.” A disclaimer is not a verification.

There is no registry to check

Verifying a certificate is harder than it sounds, because there is no national database of them. “The EPA does not maintain a database of all certified technicians,” the agency says; section 608 certification is granted by testing organizations approved by the EPA, which since 2017 have had to post lists of the people they certify, and the certificates do not expire. The list of approved programs changes, too. On May 22, 2026, eight programs left it: the EPA’s list of former programs shows two as no longer approved and six, Ferris State University’s among them after 25 years, as voluntarily withdrawn, and the agency approved four new ones the same day. Cards issued while a program was approved remain valid, so the check is not whether the issuer is approved today but whether it was approved on the date the card was issued, which is exactly the kind of rule a person at a counter cannot apply from memory and a system can. Since January 1, 2018, a new card must show the certifying program, the date it was approved, the technician’s name, the type of certification, a unique number that is not a Social Security number, and a sentence stating that the person “has successfully passed a [Type I, Type II, Type III and/or Universal—as appropriate] exam.” For a supply house, verification is therefore a stored image of the card, the fields read from it, the certifying program and its approval dates checked against the EPA’s lists, and a person or rule that looked at it. The EPA’s guidance for retailers goes further than the regulation: its page on recordkeeping says the seller “must keep a copy of the purchaser’s technician certification on file,” and that once a shop tells the seller a certified technician has left, “the seller is then prohibited from selling refrigerant to the shop.” Neither sentence is in 82.154 itself, but a store built to the guidance is safe under both, and in a store that means a refrigerant hold on the account until the shop shows that it employs a certified technician again.

The card type matters too. The regulation’s list of qualifying buyers names all four types, but the EPA’s own overview of the sales restriction adds that “individuals may only purchase refrigerant consistent with the appliances covered by their certification,” and it says flatly that section 609 technicians “cannot purchase refrigerants that are intended for use with stationary equipment, regardless of container size.” Type I covers small appliances, Type II high-pressure equipment such as split-system air conditioners and heat pumps, Type III low-pressure chillers, and Universal all three. A store that follows the guidance has to match the cylinder to the card: a Type I technician who services refrigerators and window units is not the customer for a 25-pound cylinder of R-410A.

Enforcement is rare, the penalty is per day, and provenance is a field

Sales-restriction cases against supply houses are uncommon. The only one we found on the EPA’s list of Clean Air Act Title VI enforcement actions is from 2010, when an undercover inspector found that a Massachusetts plumbing and heating supply company had sold ozone-depleting refrigerant to uncertified buyers at two of its outlets, and the agency proposed a $30,000 penalty. The enforcement energy now goes into smuggling. The first prosecution under the AIM Act, filed in San Diego in 2024, was against a man who offered illegally imported HFCs on OfferUp, Facebook Marketplace and other websites; in June 2026 a federal court in Texas sentenced a man caught at Brownsville with six 25-pound cylinders of R-410A; and the EPA reported seven civil settlements for illegal HFC imports in fiscal 2025, the largest $427,000. That matters to distributors because, under 40 CFR 84.5(f), nobody may sell refrigerant that was produced or imported in violation of the allowance rules, and “every kilogram” is a separate violation. The maximum civil judicial penalty under the Clean Air Act is now $124,426 per day for each violation. A refrigerant record that carries the importer, the lot and the certificate of analysis is cheap insurance against buying the wrong pallet from the wrong broker.

The equipment exception, and a stay from 1995

The sales restriction stops at the cylinder. The EPA says so in plain words: it “does not cover refrigeration and air-conditioning equipment or components containing refrigerants.” For a packaged unit sold with a fully assembled circuit that is simply the rule, in 82.154(c)(1)(vii). For split systems, whose outdoor units ship with a holding charge and are completed in the field, it rests on two things. Since 2016 the same paragraph has also exempted refrigerant in “an appliance component,” which the EPA describes as a part, such as a condensing unit or a line set, that cannot cool anything by itself. And a pause that has lasted three decades still covers the pre-charged kit as a whole, because in 1995 it was not clear to the EPA whether such a kit was an appliance, which was exempt, or a set of components, which then were not. Paragraph (g) of the same section reads: “the effectiveness of 40 CFR 82.154(c), only as it applies to refrigerant contained in appliances without fully assembled refrigerant circuits, is stayed from April 27, 1995, until EPA takes final action on its reconsideration of these provisions.” The reconsideration has not concluded. Between them, the component exemption and the 31-year-old stay are why a pre-charged “do-it-yourself” mini-split with quick-connect line sets can be sold to anyone under federal law, while the can of refrigerant needed to top it up cannot. Selling it and installing it are different questions, though. Asked whether certification is required to install a mini-split, the EPA’s answers for technicians say “Yes,” because “connecting or disconnecting hoses or pre-charged lines requires a section 608 technician certification.”

Maryland’s 2025 law reaches part of the same ground from a different direction. It does not mention refrigerant at all, but a mini-split or a condensing unit is HVACR equipment, so in Maryland the sale is now restricted to licensees, resellers and the exempt, a homeowner working on their own single-family house among them. For a Baltimore supply house, the result is two separate gates on two separate rules: the cylinder is checked against the buyer’s federal certification, and the equipment against the buyer’s Maryland license or exemption. A contractor account usually passes both. A homeowner may pass the Maryland gate for a mini-split and fail the federal one for the refrigerant to charge it.

What is not coming, and what is

Two refrigerant rules that a supply house may have prepared for will not arrive. The EPA’s 2021 allocation rule would have required a QR code on every HFC container and banned disposable cylinders, but the federal appeals court in Washington vacated both provisions in June 2023, in HARDI v. EPA, and the EPA removed them from the regulations in September 2024; many web pages still give their old dates. What did arrive is the agency’s October 2024 rule on HFC management, 40 CFR part 84, subpart C. Since January 1, 2026, appliances with 15 pounds or more of HFC refrigerant have been subject to leak-repair rules, with residential and light commercial air conditioning and heat pumps excluded, so a supply house’s commercial refrigeration customers now need a record of the refrigerant added to each appliance; since the same date, refrigerant sold as “reclaimed” may contain no more than 15% virgin HFC and must say so on the label. From January 1, 2028, a used disposable cylinder with refrigerant left in it may go to a refrigerant supplier, “including but not limited to distributors and wholesalers,” only if that supplier is “capable of removing the heel,” and whoever takes it must empty it before discarding it. From January 1, 2029, supermarket systems, refrigerated transport and automatic commercial ice makers must be serviced with reclaimed refrigerant only, and distributors of reclaimed refrigerant sold into those uses must report their sales by February 14, 2027, and February 14, 2028.

The larger date is also 2029. Under the HFC phasedown schedule in 40 CFR 84.7, the national cap on HFC consumption, 60% of the baseline from 2024 through 2028, falls to 30% on January 1, 2029. Allowances are counted by global warming potential, so a 25-pound cylinder of R-410A, at an exchange value of about 2,088, uses about 23.7 metric tons of allowance, against about 5.3 for the same cylinder of R-454B, and the squeeze will be felt first in the refrigerant that keeps Baltimore’s existing R-410A systems running. A supply house that can see its R-410A service demand by account and by system age will be better placed in 2029 than one that sees only last month’s sales.

The R-410A in the warehouse: barred from new systems in January, allowed again in July

If one product sums up the last two years of the HVAC supply trade, it is a pallet of R-410A condensing units that nobody can quite classify. The American Innovation and Manufacturing Act of 2020 told the EPA to phase down hydrofluorocarbons, and in its Technology Transitions rule of October 24, 2023, the agency did it subsector by subsector. For residential and light commercial air conditioners and heat pumps, the line is a global warming potential of 700. R-410A, the refrigerant in most of the systems installed in Baltimore over the past fifteen years, is far above it; the replacements the manufacturers chose, R-454B and R-32, are below it. From January 1, 2025, new self-contained equipment above the line could no longer be made or imported, and field-assembled split systems above it could no longer be installed.

Two months later the agency gave the trade a year. An interim final rule of December 26, 2023, let new R-410A split systems be installed until January 1, 2026, “where all specified components of that system are manufactured or imported prior to January 1, 2025.” Distributors ordered on that basis. Then, as the EPA itself later summarized the comments it received, 2025 sales came in below forecast, the switch to R-454B happened faster than expected, and R-454B ran short, which left R-410A units unsold in distributors’ warehouses at the very moment the new refrigerant to replace them was scarce. On January 1, 2026, the year ran out, and by the text of the regulation every new-system installation from that inventory became a violation. According to the contractors’ and distributors’ trade associations, the EPA said in late December that enforcing the deadline would be a low priority, which is a promise about enforcement, not a change to the rule.

It stayed that way for 207 days. On October 3, 2025, the EPA had proposed to let the old inventory be installed, and its final rule, published on May 26, 2026, and effective July 27, 2026, did exactly that. The change to the regulation is a few words in one sentence of 40 CFR 84.54(c)(1): where such systems “may be installed prior to January 1, 2026,” they now “may continue to be installed,” provided that, as before, “all specified components of that system are manufactured or imported prior to January 1, 2025.” There is no new deadline. The EPA called the inventory “finite and decreasing” and conceded that it has “a lack of concrete data on the number of R-410A units that remain in inventory.”

The date that matters is not on the label

That one sentence carries three conditions, and each of them is a data field a supply house may not have. The first is the phrase “all specified components.” The regulation defines a specified component as “condensing units, condensers, compressors, evaporator units, and evaporators,” so the date test applies to the indoor coil as well as the outdoor unit. A 2024 condensing unit paired with an R-410A coil made in 2025 for the repair market cannot be installed as a new system, however old the condenser is.

The second is the word “imported.” In the preamble to the final rule, the EPA answered a commenter who asked about stock moved across the border: “Legacy equipment must have been manufactured in the United States or imported into the United States before January 1, 2025. Equipment manufactured in Mexico or Canada before January 1, 2025, and imported into the United States after that date may not be installed as components of a new system.” The label the EPA requires on every unit, under 40 CFR 84.58, must show the refrigerant and “the full date, or at minimum the four-digit year, of manufacture.” It does not show the date the unit entered the country. Two condensing units with the same model number and the same 2024 on their labels can therefore have different legal answers, and the only record of the difference is in the importer’s and the distributor’s paperwork.

The third is the word “new.” Replacing a failed condensing unit on an existing system is a repair, and the final rule says so: “the replacement of a condensing unit on an existing system is allowed and is not considered the installation of a new system.” That is why R-410A condensing units made after 2024 are still legal to make and sell, labeled, under 40 CFR 84.58(b), “For servicing existing equipment only.” But a repair is defined by what it leaves in place. The regulation’s list of actions that count as installing a new system, in 84.54(e), includes “increasing the cooling capacity, in BTU per hour,” of an existing system, so a homeowner who replaces a dead two-and-a-half-ton R-410A condenser with a two-and-a-half-ton one is repairing, while one who takes the chance to go up to three tons is, in the regulation’s terms, installing a new system, which a service-market condenser made in 2025 may not be used for. And the EPA reads “replacing all components over time” as a new system too: in the preamble to the 2026 rule it wrote that “the subsequent replacement of the indoor coil would be considered the installation of a new system,” and the same is true the other way round. A system whose outdoor unit was replaced last year with a 2025-built unit cannot get a new R-410A coil this year. Under the same regulation, a system is “installed” when its circuit is completed and charged “with a full charge,” so the date of the job, not the date of the sale, is the moment the rule bites.

The software consequence is that the legal status of R-410A stock cannot live on the product record. It lives on the unit, as a serial number with a date of manufacture and, for imported stock, a date of entry, and it is decided on the order line, by the job: new system or replacement; if a replacement, the capacity of the unit being replaced; and whether the other half of the system is original or was itself replaced before. That last question is about the customer’s equipment history, which a supply house can only learn by asking, and record. A matched-system quote has to check the dates of every component in it, not only the outdoor unit. And because the rule counts violations unit by unit (under 84.54(g), every product or system sold, distributed or exported in contravention of it is “a separate violation”), the place to catch a mistake is the quote, before the unit leaves the dock. Variable refrigerant flow systems run on their own calendar, which this year’s rule left alone: components made or imported before January 1, 2026, may be installed until January 1, 2027, or until January 1, 2028, for projects with a building permit issued before October 5, 2023.

Packaged equipment runs on a third clock. A self-contained unit, which the EPA’s 2023 rule says includes “some rooftop AC units,” packaged terminal air conditioners and heat pumps, window units and portable room air conditioners, is regulated as a product rather than as a field-assembled system. Under 84.54(a)(1), one using R-410A could not be made or imported from January 1, 2025, and under 84.54(b), three years after that date, nobody may “sell, distribute, offer for sale or distribution” it either. From January 1, 2028, an unsold R-410A package unit or PTAC from 2024 cannot legally leave the warehouse at any price, and that date is printed on nothing; we described the same mechanism for household refrigerators in our article on appliance stores. For a supply house it is an inventory report waiting to be written: every self-contained R-410A unit by serial number, its date of manufacture, and the months left to sell it.

The new refrigerants arrived before the codes written for them

The replacement refrigerants bring a second question, and it is about building codes rather than the EPA. R-454B and R-32 are classed A2L, mildly flammable, and the International Code Council describes the 2024 editions of its codes as the ones in which the comfort-cooling provisions written for A2L refrigerants take effect, tied to the UL 60335-2-40 equipment standard that the EPA itself made a condition of listing them. Maryland’s Building Performance Standards are on the 2021 international codes, under COMAR 09.12.51.04, and the State’s HVACR Board adopts the mechanical code listed in COMAR 09.12.50.02-1, which is still the 2021 International Mechanical Code. Baltimore City’s 2024 edition of its Building, Fire and Related Codes, in force since May 22, 2024, adopts the 2021 mechanical code too, with its refrigeration chapter marked “[As in IMC].” Maryland proposed the 2024 building codes in the Maryland Register on June 26, 2026; we found no final adoption, and no City or County bulletin on A2L systems either way. For a supply house the consequence is mostly documentary: the A2L equipment it sells, and the leak sensors and mitigation boards that go with it, should carry their listings and installation requirements on the product page, because the permit and the inspection turn on them.

The rating belongs to a pair, and the discount belongs to the rating

Ask a supply house how efficient a condensing unit is and the honest answer is “with which coil?” Under the Department of Energy’s certification rules, the efficiency of a split air conditioner or heat pump is not a property of the outdoor box. The DOE’s rule at 10 CFR 429.16 requires ratings for “every individual combination distributed in commerce,” and for a split air conditioner with a single- or two-stage compressor, each outdoor model must include a rating for at least one coil-only combination “representative of the least efficient combination.” AHRI’s directory publishes those combinations, each with its own reference number, and that number, not the model number on either box, is what a rebate program, a specification or an inspector asks for.

Maryland is in the South, and the worst pairing decides

For air conditioners the combination also decides where a unit may legally go. The DOE’s regional standards, in 10 CFR 430.32(c), put Maryland in the “Southeast,” with Delaware, Virginia and the District of Columbia, where a split air conditioner installed since January 1, 2023, must reach 14.3 SEER2 below 45,000 Btu per hour of capacity and 13.8 at or above it. Pennsylvania, forty minutes up Interstate 83, is in the North, where the national minimum of 13.4 SEER2 applies. And the test is on the weakest link: “Any model of outdoor unit that has a certified combination with a rating below the applicable standard level(s) for a region cannot be installed in that region,” and the least-efficient combination, for most split air conditioners a coil-only one, must comply. A straight-cool condenser that a contractor can legally install in York may not be installable in Towson at all, whatever indoor coil it is paired with. Heat pumps have no regional standard, so the same rule does not apply to them.

Unusually, the regional rules name distributors directly. Under 10 CFR 429.102(c), “it is a violation for a distributor to knowingly sell a product to a contractor or dealer with knowledge that the entity will sell and/or install the product in violation of any regional standard,” or to one it knows “routinely violates” them. And under 429.142(a)(2), every distributor, wherever it is, must keep for at least 54 months from the sale the outdoor unit’s manufacturer, model and serial number, when and from whom it bought the unit, when and to whom it sold it, and, “if delivered, delivery address.” The contractor keeps its own record for 48 months, including the street address where the unit was installed. A sale of a split air conditioner is therefore a serial-number transaction with a jobsite state on it, and the jobsite, not the contractor’s billing address, is the field that decides it.

The utility’s money passes through the supply house

The combination then becomes money, and in Baltimore the money flows through the distributor in both of BGE’s programs. For business customers, BGE’s EmPOWER Maryland program offers instant discounts on high-efficiency HVAC equipment that come off the invoice when the buyer calls or visits a participating distributor. The published amounts are $375 a ton for air conditioners and air-source heat pumps, rooftop units included, $150 a ton for mini-splits, $375 a ton for variable refrigerant flow heat pumps, $1,200 for a heat pump water heater, $75 for a qualifying smart thermostat and $38 to $100 for packaged terminal units, by size. A separate electrification schedule, for equipment that replaces gas, oil or propane, pays $750 a ton for air-source heat pumps and VRF, $300 a ton for mini-splits and $1,500 for a heat pump water heater. BGE’s list of participating distributors includes Ferguson in Halethorpe, Northeastern Supply on Pulaski Highway, Johnstone Supply, Carrier Enterprise Mid-Atlantic, Aireco, Havtech and Hobbs Associates in Columbia, York and HD Supply in Hanover, and Trane’s commercial dealer in Towson.

Two lines of small print turn that into software. The first: “HVAC equipment efficiencies must be verified by Air-Conditioning, Heating, and Refrigeration Institute (AHRI) certificate.” The second, on the program’s fact sheet: “Sales tax will be calculated based on the pre-incentive price.” Take a 7.5-ton rooftop heat pump replacing a gas-fired rooftop unit at a small business, at $18,000 before the discount. The electrification rate takes $5,625 off, so the contractor pays $12,375 for the equipment, but Maryland’s 6% sales tax is $1,080, computed on $18,000, rather than $742.50, and the invoice comes to $13,455. The order line has to know the capacity in tons, what the equipment replaces, which schedule applies and the certificate that proves it, and it has to carry two prices, one for the payment and one for the tax.

For homes, the program runs through contractors, and the supply house is the gate. BGE tells contractors that to offer its residential rebates “you must be verified through a participating distributor,” and that eligible contractors “must hold a valid HVACR license, have applicable insurance coverage, and be in good standing with a participating distributor.” The Public Service Commission’s February 2026 order on EmPOWER describes the five steps that follow: the contractor buys the equipment from a qualifying distributor, installs it and submits the rebate application to the distributor; the distributor submits a rebate request to the utility; the utility pays the distributor; and the distributor pays the contractor. The program manual sets a goal of paying distributors within four to six weeks of verification, but, in the order’s words, “there currently is no requirement governing when distributors must pay contractors,” and contractors told the Commission they were waiting on significant sums. The Commission directed its staff to investigate the delays, including “the allegations discussed at the hearing regarding the filing of fraudulent claims,” and told the utilities to report how long each stage takes, from the sale to the contractor’s payment. For a supply house, that makes the rebate a ledger with five timestamps and a balance owed to each contractor, and a claim that cannot be filed twice for the same address or the same unit.

One outdoor unit, 1,222 pairings, two rebate tiers

BGE’s residential rebates, which go through participating contractors rather than through the counter, make the same point in dollars. For an air-source heat pump that is not rated for cold climates, BGE’s Tier 1 rebate requires 15.2 SEER2 and, for a split system, 7.5 HSPF2, and pays up to $500, or up to $1,500 when the heat pump replaces gas, oil or propane; Tier 2 requires 16.9 SEER2 and pays up to $1,000, or up to $2,000. Whether a given outdoor unit reaches Tier 2 depends on what it is paired with. ENERGY STAR’s public dataset of certified air-source heat pumps, updated on October 20, 2026, holds 285,054 certified combinations but only 8,583 distinct outdoor model numbers, about 33 combinations for each. The most-paired outdoor model in it, a Carrier unit listed as 27VPA924A*030*, appears in 1,222 combinations with 60 different indoor models, rated from 15.20 to 19.50 SEER2. When we queried the dataset, 976 of those combinations reached BGE’s Tier 2 line and 246 did not. Same condenser, same price at the counter, and, on BGE’s standard tiers for a heat pump that replaces electric heat, a $500 difference in the homeowner’s rebate, decided by the coil or air handler at the other end of the line set. When it replaces gas, oil or propane, the tier matters less, because 1,212 of the 1,222 pairings are also ENERGY STAR certified for cold climates and BGE pays up to $3,000 for those.

The certificate itself is a licensing question. AHRI’s directory is free to search, but its export is “limited to the first 250 records,” the full data set is sold through the data subscription described above, and AHRI’s own answer to whether a subscriber may generate certificates inside its own software is no: “the AHRI Certificate generator only exists on the AHRI Directory site,” and “static copies of certificates should not be included in software applications or catalogs.” A supply house’s system builder can show the reference number and link to the certificate; it cannot keep a library of certificate PDFs. The programs themselves are now on a clock. BGE’s residential pages say that to receive rebates on qualifying HVAC equipment in 2026, the contractor “must install your new equipment no later than December 31, 2026,” and that BGE “is awaiting a decision by the Maryland Public Service Commission about extending our energy efficiency programs into 2027.” The General Assembly has already decided part of the answer. Chapter 353 of 2026, the Utility RELIEF Act, cuts the electric companies’ EmPOWER target from 2.5% to 1.75% a year for 2027 through 2029 and requires gas companies to end their participation in EmPOWER by December 31, 2026, which ends the gas-side equipment incentives. A supply house quoting a January job should show the rebate as a separate line, with the program year it depends on, rather than baking it into the price.

The plumbing half: “lead free” is a certificate, and the category page is part of the label

A plumbing supply house has nothing as dramatic as a refrigerant transition, but it sells under a federal rule that is just as specific and much less discussed. Section 1417 of the Safe Drinking Water Act, at 42 U.S.C. 300g-6, defines “lead free” as “not containing more than 0.2 percent lead when used with respect to solder and flux” and “not more than a weighted average of 0.25 percent lead when used with respect to the wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures.” The statute even writes out the arithmetic: the lead percentage of each wetted component, multiplied by that component’s share of the product’s total wetted surface area, summed, and where a material’s lead content is given as a range, “the maximum content of the range shall be used.”

The EPA turned the statute into a product rule in 2020. Its final rule on lead-free pipes, fittings, fixtures, solder and flux, now at 40 CFR part 143, subpart B, did three things a supply house’s catalog has to reflect. Under §143.15, nobody may introduce into commerce a pipe, fitting or fixture that is not lead free, except pipe used in manufacturing or industrial processing, and “no person engaged in the business of selling plumbing supplies in the United States, except manufacturers, may sell solder or flux that is not lead free.” Under §143.19, manufacturers and importers must, with narrow exceptions, have their products certified by an accredited third party, which in practice means certification to the NSF/ANSI 372 standard, by September 1, 2023, or before the product is introduced into commerce, and keep the documentation for at least five years after the product’s last sale. The rule’s definition of a manufacturer includes anyone who has products “made under a contractual arrangement for distribution, using the person’s or entity’s brand name or trademark,” so a supply house with a house brand of valves or fittings is the manufacturer for that purpose, not just a reseller.

Two provisions make the catalog the place where this is decided. The rule “applies to any person who introduces these products into commerce, such as manufacturers, importers, wholesalers, distributors, re-sellers, and retailers,” and introducing into commerce includes “offering products for sale or distribution,” so a web listing for a pipe or fitting that is not lead free and not exempt is itself the regulated act, before anyone orders it. The EPA’s guidance adds that there is no grace period for old stock, “including stocked inventories,” and the 2020 rule dropped the proposed requirement to mark lead-free products, so nothing on the box has to say “lead free.” The catalog record is the only place the status is written down, and the civil penalty under the Safe Drinking Water Act is now up to $71,545 a day.

The exemption that depends on the marketing

The third thing is the exemption list in §143.16, and one entry in it is the most software-shaped sentence in the rule. Products “used exclusively for nonpotable services” are exempt, and the regulation gives three ways to show it: the product is “clearly labeled, on the product, package, or tag with a phrase such as: ‘Not for use with water for human consumption’”; it is physically incompatible with potable-water products; or it is “plainly identifiable and marketed as being solely for a use other than the conveyance of water,” such as air, gas, hydraulic fluid or refrigerant. A brass fitting sold for a refrigerant or gas line can be exempt. The same fitting placed in a website category called “water supply,” or described in its copy as suitable for drinking-water lines, is being marketed for something the exemption excludes.

Separately, §143.16 exempts toilets, bidets, urinals, fill valves, flushometer valves, tub fillers, shower valves, fire hydrants, service saddles and water main gate valves of two inches or more, and clothes washers, emergency drench showers and eyewashes, fire sprinklers, steam dryers and sump pumps. For the catalog, that makes lead status a small schema rather than a yes-or-no field: whether the product is lead-free certified and by whom, whether it is exempt and on which ground, the exact nonpotable marking if that is the ground, and the categories and copy that must agree with it. A search filter called “lead free” that is computed from those fields is honest. One that is typed in by hand is a liability.

Maryland adds a sale ban of its own, and a flow limit the City’s code book does not show

Maryland repeats the lead rule at the counter. Under Business Occupations §12-605.2, a person “engaged in the business of selling plumbing supplies in the State may not sell pipes, pipe fittings, plumbing fittings, or fixtures that will be used in the installation or repair of any plumbing that dispenses water for human consumption” unless they are lead free, with fines from the State Board of Plumbing of up to $5,000 a violation. Under §12-103, that section, like almost all of the State’s plumbing title, does not apply in Baltimore County, which licenses its own plumbers; there the federal rule still applies, along with the County’s own code. The statute would still allow labeled leaded solder, but the federal ban on supply houses selling it is stricter and controls. Maryland’s plumbing code, COMAR 09.20.01, adopts “the most recent version” of the International Plumbing Code and requires drinking-water components to comply with NSF 61 and NSF 372.

The rule a supply house is likeliest to miss is about water rather than lead. Since January 1, 2024, under State Government §9-2006 and COMAR 14.26.03, new faucets, showerheads, toilets, urinals and spray sprinkler bodies “may not be sold or offered for sale in the State” unless they meet Maryland’s efficiency limits: 1.5 gallons a minute for a private lavatory faucet, 1.8 for a residential kitchen faucet, which may offer a temporary 2.2 if it “defaults to a maximum flow rate of 1.8” after each use, 0.5 for a public lavatory faucet, 2.0 for a showerhead, 1.28 gallons a flush for a toilet and 0.5 for a urinal. Since 2025 the same products may not be installed for profit. Two details make this a data problem rather than a buying decision. Baltimore City’s plumbing code, the 2021 International Plumbing Code, still prints the looser national figures, 2.2 and 2.5 gallons a minute and 1.6 a flush, so a counter that checks the City’s code book instead of the State’s statute will stock faucets it may not sell. And the EPA’s WaterSense label, which can prove compliance for a bathroom faucet, is not available for kitchen faucets at all, so the proof for those has to come from one of the certification databases the regulation accepts. The one exemption that matters to a distributor covers products “sold at wholesale inside the State for final retail sale and installation outside the State,” which is a fact about the order, not about the product.

Baltimore’s lead lines are all on the customer’s side

The demand is in the ground. Under the EPA’s Lead and Copper Rule Improvements, published in October 2024, water systems must begin complying by November 1, 2027, and replace every lead and galvanized-requiring-replacement service line under their control within ten program years, which runs to the end of 2037. Water utilities challenged the rule in the D.C. Circuit, which heard argument on September 30, 2026, and the EPA has defended it. Baltimore’s public service-line inventory, a map layer last updated on October 19, 2026, lists 8,847 lead lines, 564 galvanized lines requiring replacement and 67,503 lines of unknown material in the City; across the system that the City and Baltimore County share, it lists 8,924 lead lines, 1,020 galvanized ones and 172,730 still unknown. Every lead and galvanized record in it is on the customer’s side of the meter. At the rule’s pace of 10% a year, that is about a thousand customer-side replacements a year for a decade, each one a bill of materials of service tubing, curb stops, meter setters and couplings that must all be certified, and, in the City, a code that bars Type M copper for underground water service. A supply house that can tie each of those orders to an address, a material and a certification is selling exactly the record the work will need.

What Baltimore and Annapolis add: a permit for every swap, a cap on supplier credit, and an 80-degree rule

Baltimore City’s rules sit on top of the State’s. Two of them reach the supply house, and a third change, made in Annapolis, brings it demand. The first is the permit. The City’s Building, Fire, and Related Codes, in their 2024 edition, say that “no heating, ventilation, air-conditioning, or refrigeration (‘HVACR’) work may be undertaken before the Building Official has issued a permit for that work,” that the application must name “the insured, licensed HVACR contractor,” and that a permit may be issued only to an HVACR contractor “licensed to do business in the City,” whose license is registered in the City’s E-Permits system with an access code that the Department of Housing and Community Development gives only to the license holder. The department’s list of work exempt from permits, for one- and two-family homes, covers portable appliances and self-contained systems with “10 pounds (4.54 kg) or less of refrigerant,” and little else. A condenser swap, a new mini-split or a replacement furnace needs a permit, and plumbing permits go only to a master plumber or master gas fitter licensed to do business in the City. Licensing itself splits three ways around the city line. Baltimore City relies on State plumbing licenses but keeps its own registration for gas fitters, and only a registered Master Gas Fitter of Baltimore City may apply for a gas permit; every master plumber, gas fitter, HVACR contractor and home improvement contractor doing business in the City must also register with the City for $25. And under §12-103 of the Business Occupations Article, Maryland’s plumbing statute “does not apply to Baltimore County,” which licenses its own master plumbers; the State’s HVACR law recognizes a master plumber’s license “issued by the State, Baltimore County, or the Washington Suburban Sanitary Commission.” For a supply house, the account’s jurisdiction decides which license number is the right one to ask for.

The permit is cheap and skipping it is not. Under the code’s fee schedule, air conditioning costs “$5 a ton,” with a minimum of $30 and a maximum of $300 per unit, a fuel-burning appliance up to 200,000 Btu per hour costs $30 and an electric water heater $20, a one- or two-family application adds $25, and a 5% permit tax is added, rounded up to the next dollar. A three-ton heat pump replacement in a rowhouse therefore comes to $57 in City fees, a gas furnace with a three-ton condenser $88, and an electric water heater $52, because the permit fee itself has a $25 minimum. Work done without a permit carries a surcharge of “the greater of $1,000 or 50% of the permit fee.” A supply house that prints the expected permit fee on a quote, and asks for the permit number when it delivers to a City address, is doing its contractors a favor that costs it one lookup table.

The second is supplier credit on City-funded jobs. Under Article 5, §28-37 of the City Code, a bidder may count 100% of what it spends with a certified minority- or women-owned business that is “a wholesaler warehousing the goods supplied,” but “only 25% of the applicable contract goal may be attained by expenditures to certified business enterprises that are non-manufacturing suppliers,” and the supplier has to perform a commercially useful function, negotiating the price, ordering the material and paying for it. A certified supply house selling into City work needs invoices that show exactly that, job by job.

The third is demand. Chapter 664 of 2026 requires landlords of apartment buildings with ten or more units to keep each unit at “not greater than 80 degrees Fahrenheit at 3 feet above the floor level” from June 1 to September 30: from June 1, 2026, in new buildings and in units where the landlord has provided air conditioning at any time since January 1, 2025, and from October 1, 2026, in units renovated with new electrical or heating systems. The Utility RELIEF Act sets aside $72.65 million for the Maryland Energy Administration to put heat pumps in low- and moderate-income homes, through a rebate program still being designed, and $18.85 million for heating and cooling in Baltimore City public schools. Each of those programs will arrive at a supply-house counter as orders with paperwork attached.

What Baltimore’s supply houses show online

To see how much of this the local trade already handles on the web, we built a list of every counter or will-call branch of a wholesaler whose main business is heating, cooling, refrigeration or plumbing supply to contractors, placed each address on the map with the Census Bureau’s geocoder, and kept those inside Baltimore City or Baltimore County. We left out home centers, contractors, general industrial suppliers and pipe-and-valve houses. The result was 26 locations, 25 counters and a showroom, belonging to ten companies, with another 20 branches within 15 kilometers in Anne Arundel, Howard, Carroll and Harford counties. Only seven of the 26 are inside the City. R.E. Michel and Aireco Supply have six each, Ferguson three and a showroom, Northeastern Supply three, United Refrigeration two, and Hajoca, Lennox, Trane Supply, Sid Harvey and APR Supply one each. OpenStreetMap knew about only 8 of the 46 branches, so the companies’ own store locators did most of the work, and the mailing address proved a poor guide to the jurisdiction: six of the 19 County locations give their city as Baltimore, an R.E. Michel branch addressed to Rosedale is inside the City, and a Ferguson branch at “Baltimore, MD 21226” is in Anne Arundel County.

Every distributor site we could check for it, eight in all, runs an online ordering portal for account holders, and none of the six whose pricing we could check shows a price to a visitor who is not logged in. On the one site with a public product interface, an anonymous request returns a list price of zero. The rules from the earlier sections are almost invisible. Of the eight heating and refrigeration distributors whose sites we read, one shows Maryland’s equipment-sales notice: LennoxPROs, the dealer site of Lennox’s company stores, carries it on every page, citing the statute and the penalties. One states the EPA’s refrigerant rule: United Refrigeration publishes a form, citing 40 CFR 82.154, on which a contractor submits copies of the section 608 or 609 cards of a company representative and of every technician, with each certifying organization and ID number, signed by an officer and updated when the representative leaves. That is the best implementation of the federal rule we found anywhere. Two of the eight explain the A2L refrigerant change in any depth, and a third has a catalog section for A2L-rated tools. One has a matched-system tool, Lennox’s AHRI Matchup. One names BGE’s rebate: Aireco has a page explaining that equipment must be bought through Aireco and be AHRI-rated, that applications are due within 90 days of installation and that the credit goes to the contractor. None mentions EmPOWER by name. On the plumbing side, Hajoca publishes a “Lead Free Laws” page.

The account applications tell the same story from the other end. We read four credit applications in full. All four ask for a personal guarantee with the guarantor’s Social Security number, and all four ask for a tax-exemption certificate if the buyer claims one. None asks for an EPA refrigerant card, and only Hajoca’s asks for a contractor’s license number. The documents a Maryland supply house now most needs from a new account, the license that qualifies it to buy equipment and the cards that qualify its technicians to buy refrigerant, are the two that its standard paperwork does not collect, while it collects the most sensitive personal number there is and then has to protect it.

For search engines and AI assistants the sites are close to blank. Only three of the eight home pages we could read carry any structured data, those of Aireco, Hajoca and LennoxPROs; Ferguson’s branch pages carry LocalBusiness markup with the address and coordinates; none of the three product pages we tested carries Product or Offer markup; and none of the ten sites we checked has an llms.txt file. Most allow AI crawlers; one national refrigeration distributor blocks OpenAI’s GPTBot alone, and one plumbing distributor’s branch stores share a robots.txt that blocks the training crawlers but not Perplexity’s, which looks like its store platform’s default rather than a decision. Three pages are out of date in ways that matter: one A2L page still gives January 1, 2026, as the last day to install most R-410A split systems, a transition page on another site still calls the EPA’s change a proposed rule, and a third site’s page of regulatory updates links nothing newer than 2021. The practical side is better covered: four of the nine sites offer the company’s own mobile app, five of the nine mention an after-hours or emergency line, and Ferguson offers pickup lockers at “select locations.”

What online sellers do when you try to buy refrigerant

To see how the federal rule works on the open web, we looked at 32 online sellers of refrigerant and heating and cooling equipment in the United States: online-only HVAC retailers, the marketplaces and big-box chains, distributors’ own web stores and refrigerant specialists. We bought nothing, created no accounts and stopped before payment. Seventeen of the 32 blocked our connection, which comes from Lithuania, so the counts below are for the 14 we could read, plus one we saw only through search results; a reader in the United States would see more.

The marketplaces have simply opted out. Amazon’s policy for sellers, last updated in October 2025, prohibits “substitute refrigerants that are legal for sale only to certified technicians” and listed HFCs, which covers R-410A, R-32 and R-454B, and it offers no way to upload a certificate. Walmart Marketplace prohibits ozone-depleting substances and non-exempt substitute refrigerants, and eBay disallows HFCs. Our searches on Amazon and Walmart found gauges, adapters and recovery tanks but no cylinders of R-410A, R-454B or R-32. The certificate check, where it happens at all, happens on the specialists’ and distributors’ own sites.

We read 12 listing pages for stationary refrigerant cylinders at seven sellers. Six of them, at two sellers, would not add the cylinder to the cart until certificate details were entered. Two showed a certification form or attestation on the product page. Two required a trade-account sign-in before showing a price. Two showed, at most, a notice, and one of those let us add a cylinder to a guest cart with no prompt at all. Only two of the seven sellers say they verify the certificate before shipping, which is the step the EPA says is required; a mandatory text box accepts whatever is typed into it. The two that do it properly are worth naming. PES Supply’s page for a 25-pound cylinder of R-410A will not add it to the cart until every certificate field is filled in, including an uploaded image of the card, and the seller states that it verifies before shipment. MiniSplitSystemsDirect’s R-410A and R-32 pages require either a section 608 number or an employer or reseller attestation, cite 40 CFR 82.154 and say the certificate is checked before the order ships. Johnstone Supply, United Refrigeration and LennoxPROs keep refrigerant behind a trade login, where any check happens out of view.

Three smaller findings are worth a supply house’s attention. A 1.8-pound can of R-32 sold for recharging mini-splits went into a guest cart unchallenged at one seller; the small-can exception in the regulation covers only car air-conditioning refrigerant with a self-sealing valve, so a stationary refrigerant in a small can is still a restricted sale. All six listing pages for A2L refrigerants named the safety class and four said the gas is flammable, but one distributor described R-454B as an “HFO,” when it is a blend of the HFC R-32 with an HFO, and one specialist’s live product page still carried a drafting note reading “[NEEDS VERIFICATION …].” And the states add their own rules on top. Washington’s Department of Ecology fined Amazon $800,068 and Walmart $383,388 in March 2026, according to the Washington State Standard, for selling car air-conditioning cans of R-134a that the state’s HFC law bans; keyword screening had missed them. A store that ships nationally needs its rules keyed to the destination state and the product’s attributes, not to words in its title.

Do-it-yourself mini-splits are the mirror image. Five of the sellers whose pages we could read list them, and none of the five asks for a certificate, which matches the federal rule: refrigerant inside an appliance component is outside the sales restriction, and the 1995 stay still covers the pre-charged kit as a whole. The argument is about installation rather than sale. One manufacturer markets its do-it-yourself line with the promise that no license and no technician are needed, while the EPA’s questions and answers for technicians say that installing a mini-split, including “connecting or disconnecting hoses or pre-charged lines,” requires section 608 certification, and the regulation’s definition of a technician includes “installers.” In Maryland, the state’s licensing law answers the question more plainly, as we described above: a homeowner may install equipment in a single-family house they own, while a tenant installing a mini-split, or a handyman hired to do it, needs a license.

The e-commerce half: a supply house’s online store is a counter with a license desk

Everything in the sections above happens at a counter today, in the heads of people who have worked it for years. The counter knows which contractors are licensed and which technician’s card is in the drawer, that a homeowner asking for a mini-split needs a different conversation, that the coil going out with that condenser is new and the condenser is not, and that the BGE discount needs the AHRI number written on the ticket. An online store has to ask all of that without the person. That is why most supply-house websites stop at a catalog and a login, and why the ones that sell properly look less like a shop and more like an account system with a shop attached.

Sell to the account, and let the account carry the rules

The center of a supply house’s online store is not the product page; it is the account. Opening one should collect what the rules ask for once, so that checkout does not have to: for equipment in Maryland, the Maryland license number with its type and expiry, or the reseller status, or the exemption the buyer is claiming; for refrigerant, an image of each technician’s card, its type and its issuing program, checked against the EPA’s approval dates; the people who may buy on the account and accept deliveries; resale and tax-exemption certificates; and payment terms. A license that lapses or a technician who leaves should change what the account can buy the same day, online and at the counter, because the knowledge standard in Maryland’s law and the EPA’s guidance on departed technicians both turn on what the seller knew.

Once the account carries the rules, the store can be generous about everything else. Prices can be public, or shown after login at the account’s own level, without endangering anything, because what is restricted is the sale, not the browsing. A homeowner can see the mini-split, read the notice Maryland requires and declare the exemption at checkout, with the declaration stored on the order. A contractor whose account is verified never sees any of it.

The order line has to know the job

The second piece is the order line. A line for an R-410A condensing unit needs three answers before it can be priced: is the job a new system or a repair, if a repair what capacity is being replaced, and is the other half of the system original or replaced before. A line for a split air conditioner needs the state where it will be installed, which decides whether the DOE’s Southeast standard applies, and the serial number of the unit that ships, which the distributor must keep for 54 months together with the buyer and the delivery address. A line for a heat pump that qualifies for a BGE discount or rebate needs the AHRI reference number of the matched system, the tonnage it certifies, what the heat pump replaces, which decides between the ordinary and the electrification schedule, and, for an instant discount, two prices: the discounted one the contractor pays and the full one on which sales tax is computed. None of these are exotic fields. They are simply fields that a general-purpose cart does not have, because nothing in ordinary retail needs them.

Sell the system, not the box

The third piece is a system builder, and it is where a supply house’s store can be genuinely better than the national chains’ for the products that matter most. Choosing an outdoor unit should produce the list of certified pairings for it, each with its AHRI reference number, its SEER2, EER2 and HSPF2, its refrigerant and its ENERGY STAR status, the BGE rebate or discount tier it reaches, whether it can be installed in Maryland if it is a straight air conditioner, and, for R-410A stock, whether every component in it predates 2025. Lennox already tells investors that its dealer site makes AHRI-matched suggestions; an independent can do the same from AHRI’s licensed data, provided it holds the license itself, links to AHRI’s certificate rather than storing copies, and shows the rebate as a separate line with the date it is valid until, because BGE’s 2027 budget is not yet set.

Terms, mornings and the will-call counter

The fourth piece is the part of the trade no consumer platform was built for. Contractors buy on account, at account prices, on terms, and many of them pick up before sunrise: Ferguson’s Halethorpe branch lists weekday hours from 5:30 in the morning, and R.E. Michel lists Saturday counter hours at its Baltimore branches. An online order placed at 9 p.m. for a 6 a.m. will-call pickup, with the pick ticket ready and the refrigerant released only to a person on the account’s list, is worth more to a contractor than free shipping. Pickup lockers, which Ferguson describes in its annual report as part of its fulfillment network, push the same idea further. Statements, payments by ACH and the ability to see what a job cost across six tickets belong in the same portal, because the contractor reconciles by job, not by order.

What Google, ChatGPT and the marketplaces will and will not do

A supply house cannot hand any of this to someone else’s storefront. Amazon, Walmart and eBay prohibit HFC refrigerants outright, as described above, so the certificate check has nowhere to happen but the supply house’s own checkout. Google Shopping has no rule against refrigerants, but its guidance for business-to-business merchants asks for the highest price anyone could pay and for products individuals can buy, which sits awkwardly with a restricted sale; Google’s own merchant-listing rules require a price above zero on a page where the item can be bought, so a “log in for price” page is not eligible. Google’s checkout inside AI Mode and Gemini, built on its Universal Commerce Protocol, excludes items bundled with installation or setup, items that need freight, final-sale and pre-order items, and anything Shopping blocks, and products have to be opted in one at a time. OpenAI has moved its shopping toward checkouts on merchants’ own sites, and its product feed specification says plainly that “warning and age-restriction fields do not establish purchase restrictions.” Every channel, in other words, sends the restricted sale back to the merchant’s own store.

What the channels can do is find the store, and that is where structured data earns its keep. Schema.org already has the vocabulary a supply house needs: an Offer can say whom it is for with eligibleCustomerType, whose values include Business and Reseller, and a Product can carry a certification. Google’s Merchant Center accepts an ENERGY STAR certification attribute for products in the United States, which for a split system belongs on the system, not the condenser. Google has also said, in its guide to optimizing for generative AI features, updated in July 2026, that its search does not use llms.txt files at all, so the work that matters is accurate pages and current Merchant Center and Business Profile data. The category names matter more than they look: Google Business Profile has categories called “Air conditioning system supplier,” “Plumbing supply store” and “Heating equipment supplier,” and none called HVAC supply house, so a supply house filed as an “HVAC contractor” is telling Google it is the customer, not the counter.

There is an opportunity here as well as a chore, because the pages that rank for the questions contractors and homeowners actually type are poor. When we checked searches such as “buy refrigerant online” and “r410a for sale,” seven of the nine results for each were spam pages hosted on hijacked or unrelated domains, one of them claiming that the EPA had banned R-410A, and no EPA page ranked for any of the refrigerant or certification queries we tried. Pages from trade associations that still rank say that installing new R-410A systems became illegal on January 1, 2026, which was true for 207 days and is not true now. Google’s autocomplete suggests “hvac supply near me that sells to the public” and “can i buy r410a without a license.” A Baltimore supply house that answers those questions correctly, with dates and citations, on its own site, will be the page an AI assistant can quote, and it will be telling the truth when the assistant’s other sources are not.

A note for readers in Lithuania

We write mostly for Baltimore, but part of our team and many of our readers are in Lithuania, and this time the comparison is unusually direct, because the European Union has answered, in plain text, the question the EPA left open in 1995. Regulation (EU) 2024/573 on fluorinated greenhouse gases, in force since March 11, 2024, says in Article 11(7) that non-hermetically sealed equipment charged with those gases “may only be sold to an end user where evidence is provided that the installation is to be carried out by an undertaking certified” under the regulation, and Article 7(4) requires the seller to keep records “of the equipment sold and of the certified undertakings that will carry out the installation” for at least five years. In the United States, a pre-charged mini-split can be shipped to anyone; in Lithuania, the shop needs to know who will install it before it may sell it.

The EU’s bans also hang on a different event. Where the EPA’s rule turns on manufacture, import and installation, Annex IV of the regulation turns on the date a product is first placed on the EU market: single split systems with less than 3 kilograms of gas and a global warming potential of 750 or more since January 1, 2025; split air-to-water systems up to 12 kilowatts with a GWP of 150 or more from January 1, 2027; split air-to-air systems up to 12 kilowatts with a GWP of 150 or more from January 1, 2029, which is the date R-32, at 675, leaves the small split market; and fluorinated gases of any kind in splits up to 12 kilowatts from 2035. One year after each date, older stock may be sold on only “if evidence is provided that the product or equipment was placed lawfully on the market prior to that date.” The EU, in other words, wrote down the date-of-entry field that the American label leaves out. And its rule for spare parts draws the same line as the EPA’s: parts for repairing existing equipment remain on sale, provided the repair does not increase the equipment’s capacity, its charge or the GWP of its gas.

The rule Lithuanian web shops most often appear to miss is about advertising. Article 12(16) requires that, for equipment containing gases with a GWP of 150 or more, the label information, that the product contains fluorinated gases, which gas, the charge in kilograms and in metric tons of CO₂ equivalent, and the GWP, “shall also be included in descriptions used for advertising,” which on our reading includes a product page. We looked at 24 Lithuanian web shops on October 21 and captured a split air-conditioner listing at 13 of them. Eleven named the refrigerant and at least three showed the charge, but none showed a numeric GWP or a CO₂-equivalent figure, and none asked for evidence of a certified installer on the product page. Six offered installation as a service or a bundle, all of them specialist shops; none of the five general retailers did. The good examples are worth naming: komfo.lt shows the charge and says in its answers that the work may be done only by certified specialists, geraskondicionierius.lt sells its units with installation included, orokon.lt, izopaga.lt and airway.lt offer installation, and kondicionieriai24.lt at least describes its R-32 as a low-GWP refrigerant, though without the number. One specialist listing still advertised an R-410A single split in October 2026, a category that may not be newly placed on the EU market since the start of 2025.

Lithuania enforces the retail rule with fines aimed at exactly this sale. Under Article 110¹ of the Law on Environmental Protection, added in 2024, selling non-hermetic equipment charged with fluorinated gases to an end user in breach of the requirements costs a company from €2,000 to €4,000, and under Article 309 of the Code of Administrative Offences an individual or manager €1,000 to €2,000; labeling breaches carry half that. As in the United States, we found no lookup service for installers: the Environmental Protection Agency, Aplinkos apsaugos agentūra, publishes an anonymized spreadsheet of certificate holders, 337 entries in its January 2, 2026, edition, and the data is otherwise held in the ALIS permits system. A Lithuanian shop that wants to obey Article 11(7) at checkout has to ask the buyer for the installer’s company code and certificate number, or sell its own installation, and keep the pair for five years.

The money is shaped differently too. The household boiler-replacement compensation is now administered by the Lithuanian Energy Agency, LEA, rather than APVA, and pays up to half of a fixed rate per kilowatt of rated heating capacity: €316.10 for an air-to-air heat pump, and, for an air-to-water heat pump without a tank, €903.49 per kilowatt up to 7 kilowatts but €591.38 above that, up to 13 kilowatts. A 7-kilowatt unit therefore earns €3,162.22 and an 8-kilowatt unit €2,365.52, €796.70 less for the bigger machine, which is exactly the kind of cliff a quoting tool should show. LEA’s guidance for applicants lists the documents to submit, the invoice, a signed installation act, the technical file and photographs, and the installer’s F-gas certificate is not among them. By October 19, LEA had paid €74.33 million to 22,688 households, and the next call opens on January 4, 2027. Lithuania applies its standard 21% VAT to heat pumps and their installation, with no reduced rate. When 15min wrote in 2023 about what makes a heat pump work well, manufacturers’ representatives “rekomenduoja kartu su įranga pirkti ir montavimo paslaugą,” that is, they recommend buying the installation together with the equipment. The EU has made a version of that advice a legal requirement for end-user sales. Maryland’s 2025 law points a Baltimore supply house in the same direction for any buyer who is not licensed.

What custom actually costs, and when it pays

We price every project at a fixed fee, agreed before we start, and publish the starting points on our pricing page. For a Baltimore supply house, whether it sells heating and cooling equipment, plumbing, refrigeration or all three, the packages map onto this article like this.

Most of our projects land between $6,000 and $30,000, and none requires you to give up an ERP, an accounting system or a payment processor that already works; the demos page shows finished work. In Maryland, the state’s 3% tax on software and IT services applies to a custom build, so the Online Store package starts at $6,180 with tax and a Custom App at $12,360.

Whether custom pays depends on what it replaces, and three numbers frame it. The first is other people’s money: a supply house that processes BGE claims for its contractors is handling $150 to $750 a ton on commercial equipment and up to $5,000 a heat pump on homes, and a claim rejected for a missing AHRI number, or filed twice for the same address, costs a contractor relationship as well as the rebate. The second is exposure: up to $1,000 for a first and $5,000 for each later violation of Maryland’s equipment-sales law, and an inflation-adjusted maximum of $124,426 a day per violation under the Clean Air Act, all of which well-kept account records help avoid. The third is inventory: an R-410A package unit that cannot be sold from January 1, 2028, or a condensing unit that may only go into a repair, is worth what the system knows about it. Against those, a $3,500 Prototype Sprint that sorts the R-410A stock and audits the accounts, or a $6,180 online store with the gates built in, is a small number. The honest test is whether a supply house actually has the problem, and an hour with its account list and its serialized inventory usually answers that.

What we would build for a Baltimore supply house

We would not build an ERP. The distribution systems this trade runs on have spent decades on branch inventory, purchasing, vendor rebates, pricing matrices, counter tickets and accounts receivable, and a supply house that has one working should keep it. We would not build an accounting system, a payment processor or a delivery routing tool either, and we would not try to replace the manufacturers’ and AHRI’s product data. What we would build is the layer that sits on top of all of them and that the rules of the last two years now require: a record of who may buy what, which unit is which, and what job each sale is for.

The first piece is the account as a compliance record. Every account carries the route by which it may buy equipment in Maryland, a license number with its type and expiry, a reseller status or a stated exemption, together with the people authorized to buy on it and, for each technician who buys refrigerant, a stored copy of the certificate with its type and the issuing program checked against the EPA’s list. A license that expires or a technician who leaves changes what the account can buy the same day, at the counter and online.

The second is a unit-level inventory. Condensing units, air handlers, coils and package units are tracked by serial number, with the date of manufacture and, for imported stock, the date it entered the country, so that the R-410A question has an answer before anyone asks it. The same record carries the product’s refrigerant, its capacity and its AHRI pairings, and for plumbing items the lead-free certification or the ground for an exemption. It is mostly data a supply house already receives, from manufacturers’ advance ship notices, serial labels and certification listings; it is rarely kept in one place.

The third is an order line that knows the job. For R-410A equipment it asks whether the job is a new system or a replacement and, for a replacement, the capacity of the unit being replaced, and it refuses a combination the regulation does not allow. For a heat pump or air conditioner it builds the matched system, shows the AHRI reference number, checks the dates of every component, applies the utility discount the system qualifies for and computes tax on the price before the discount. For equipment sold in Maryland it prints the notice, and for refrigerant it releases the line only to a certificate that covers it.

The fourth is the online store, built on the same rules rather than beside them: one catalog, prices that depend on the account, the same gates at checkout as at the counter, pickup scheduling for the early morning trade, and product pages marked up so that search engines and AI assistants can read what each item is, whom it is sold to and what it is certified for. The fifth is the binder: refrigerant invoices for three years, the notices given, discount claims and their payments, certificates and licenses with their dates, and reports by buyer type for whichever agency asks first. None of it replaces the ERP. It reads from it and writes back to it, on the supply house’s own database, exportable in full and the supply house’s to keep.

Build, buy, or leave it alone

Most supply houses should buy almost everything and build very little. The ERP, the accounting system, the payment processor, the sales tax engine and the shipping and routing tools are mature products, and a branch that sells to a few hundred contractors who all hold licenses and all have refrigerant cards on file may have no problem this article can solve. A plumbing house whose equipment sales are a small share of revenue, whose customers are licensed plumbers and whose catalog already carries certification data may need nothing more than a cleaner online store, and we would say so on a call.

Choose vendors by the meter rather than the logo. Distribution ERPs are quoted rather than published; general platforms charge per user, as Business Central does at $80 to $110 a month, or per plan with a catalog limit, as Shopify does with three B2B catalogs below Plus and BigCommerce with price lists only on its Performance plan; product data is licensed by the year, $4,123 from AHRI for a HARDI distributor that gives its tools away free; tax engines charge per state or per order; and the card processor, at roughly 2.3% to 3% of every card sale, is the largest meter of all. Ask for the full price in writing, including implementation, what renews automatically and what the price becomes in year two, and then ask every vendor these questions before you sign:

• Can the system store, for each account, a Maryland license number with its type and expiry, or the exemption a buyer without a license claimed, and stop an equipment sale that has neither, at the counter and online?
• Can it store each technician’s refrigerant certificate with its type, and stop a cylinder the certificate does not cover?
• Does it track condensing units, coils and package units by serial number with dates of manufacture and import, and can it tell me which R-410A units may go into a new system today?
• Can an order line record whether the job is a new system or a replacement, and the capacity of the unit being replaced?
• Can it build a matched system with its AHRI reference number, apply BGE’s instant discount and calculate sales tax on the price before the discount?
• Who owns my account, sales and product data, and can I export all of it, in full, whenever I like, including after I leave?

A vendor that answers all six well has earned the contract. Build when the honest answers are “a spreadsheet,” “the counter knows” or “we would have to customize that,” for the questions that carry your risk: when licenses are checked once at account opening and never again, when refrigerant cards live in a drawer, when nobody can say which of the R-410A units in the warehouse can still go into a new system, or when the utility discount is claimed from memory at the end of the month. Leave alone what is cheap and works: the ERP, the accounting, the tax engine, the payment processor and the relationships with the contractors who have bought from the same counter for twenty years.

Our guide to custom software in Baltimore explains how we work, our article on appliance stores covers the retail side of the same refrigerant rules and BGE’s programs, our article on home improvement contractors covers Maryland’s contractor licensing and deposit rules, and our article on field-service software covers the contractors on the other side of the counter. If you want to find out which of these would pay for you, bring us an export of your active accounts, your serialized equipment inventory and last quarter’s invoices, and we will show you.

Frequently asked questions

Can a homeowner buy HVAC equipment from a supply house in Maryland?

Sometimes. Since October 1, 2025, Maryland Business Regulation §9A-501.1 has barred a seller from knowingly selling heating, ventilation, air-conditioning or refrigeration equipment to anyone who does not hold, or employ someone who holds, a master, master restricted or limited HVACR license, does not resell to licensees, and is not exempt from licensing under §9A-103. One exemption covers an individual owner of a single-family dwelling working on a building they own, so a homeowner installing equipment personally may buy it. Every buyer must also be given a written notice about the licensing requirement at the time of sale. Sellers of general construction materials that get less than 25% of revenue from HVACR equipment are exempt from the buyer check, but not from the notice.

Do you need a license or certification to buy R-410A refrigerant?

Yes. Under 40 CFR 82.154(c), refrigerants such as R-410A, R-454B, R-32 and R-134a in cylinders may be sold only to technicians certified under section 608 of the Clean Air Act, or under section 609 for car air-conditioning refrigerant, to employers of certified technicians who provide proof, to buyers for resale, or to appliance manufacturers. The exception is car air-conditioning refrigerant in cans of two pounds or less with a self-sealing valve. Sellers must verify the certification and keep invoices showing the buyer, the date and the quantity for three years, and the same rules apply to online sales.

Can R-410A air conditioners and heat pumps still be installed in 2026?

In part. Under the EPA’s Technology Transitions rule, as amended effective July 27, 2026 (91 FR 31284), a new residential or light commercial R-410A split system may be installed only if every specified component, the condensing unit, the coil and the other listed parts, was manufactured in or imported into the United States before January 1, 2025. Between January 1 and July 26, 2026, the rule’s text did not allow even that. Replacing a failed condensing unit on an existing system with one of the same capacity is a repair and is allowed at any time, even with a unit made later and labeled “For servicing existing equipment only.” Increasing capacity, or later replacing the other half of the system, counts as installing a new system. Packaged R-410A units may not be sold at all from January 1, 2028.

Is there an EPA 608 certification lookup?

No national one. The EPA says it “does not maintain a database of all certified technicians.” Certificates are issued by EPA-approved testing organizations, which since 2017 have had to post lists of the technicians they certify, and the certificates do not expire. A seller checks the card’s required wording and number and whether its issuing program was EPA-approved on the date the card was issued, using the EPA’s lists of approved and formerly approved programs; eight programs left the EPA’s approved list on May 22, 2026, six of them voluntarily, but cards they issued while approved remain valid.

Can I install a ductless mini-split myself in Maryland?

Maryland’s licensing law lets an individual owner of a single-family dwelling do heating and cooling work on a building they own, and a homeowner may buy the equipment for that purpose. Federal law does not restrict the sale of pre-charged mini-split equipment, because 40 CFR 82.154(c)(1)(vii) exempts refrigerant in an appliance component and a stay in 82.154(g) that dates from 1995 still covers the kit as a whole, but the EPA’s questions and answers say that installing a mini-split, including connecting pre-charged lines, requires section 608 certification, and only certified technicians may buy refrigerant to charge one. In Baltimore City, a mini-split installation also needs a permit, which is issued only to a licensed HVACR contractor.

What is an AHRI matched system, and why does it matter for rebates?

An AHRI matched system is a specific combination of an outdoor unit and an indoor coil or air handler, and sometimes a furnace, whose efficiency has been certified together and given its own AHRI reference number. Under the Department of Energy’s rules, the efficiency rating of a split air conditioner or heat pump belongs to the combination, not to either unit. BGE’s programs require an AHRI certificate, and the same outdoor unit can qualify for different rebate tiers depending on the indoor unit it is paired with.

How do BGE’s HVAC discounts and rebates work?

For business customers, BGE’s EmPOWER Maryland program gives instant discounts at participating distributors, such as $375 a ton for efficient air conditioners and heat pumps and $750 a ton for heat pumps that replace gas, oil or propane, verified by an AHRI certificate. For homes, rebates of up to $400 to $5,000 for heat pumps, depending on type, tier and fuel, are paid through participating contractors, who must be verified through a participating distributor; the contractor submits the application to the distributor, the distributor claims from BGE and then pays the contractor. BGE says 2026 rebates require installation by December 31, 2026, while it awaits a Public Service Commission decision on 2027.

Is sales tax charged before or after BGE’s instant discount?

Before. BGE’s fact sheet for its commercial instant HVAC discounts says: “Sales tax will be calculated based on the pre-incentive price.” On an $18,000 rooftop heat pump with a $5,625 discount, Maryland’s 6% sales tax is $1,080, not $742.50.

What SEER2 does a new air conditioner need in Maryland?

Maryland is in the Department of Energy’s Southeast region, so a split-system central air conditioner installed since January 1, 2023, must reach at least 14.3 SEER2 below 45,000 Btu per hour and 13.8 SEER2 at or above it, against 13.4 SEER2 in northern states such as Pennsylvania. The outdoor model’s least-efficient certified combination must meet the standard. Heat pumps have no regional standard; the national minimum for a split heat pump is 14.3 SEER2 and 7.5 HSPF2.

What records does an HVAC distributor have to keep?

For refrigerant, invoices showing the purchaser’s name, the date of sale and the quantity, plus any proof that an employer-buyer employs a certified technician, for three years (40 CFR 82.154(c)(3)). For split-system central air conditioners, under 10 CFR 429.142, every distributor must keep, for 54 months from the sale, the outdoor unit’s manufacturer, model and serial number, when and from whom it was bought, when and to whom it was sold, and the delivery address if delivered.

Did the EPA ban disposable refrigerant cylinders or require QR codes?

No. Those provisions of the EPA’s 2021 HFC allocation rule were vacated by the D.C. Circuit in June 2023 and removed from the regulations in September 2024. What applies instead, from January 1, 2028, is a rule on leftover refrigerant: a used disposable cylinder with a heel may go to a reclaimer or to a refrigerant supplier, including a distributor, that is capable of removing it, and whoever receives it must empty it before discarding it.

What does “lead free” mean for plumbing products?

Under section 1417 of the Safe Drinking Water Act, lead free means no more than 0.2% lead in solder and flux, and no more than a weighted average of 0.25% lead on the wetted surfaces of pipes, fittings and fixtures. Since September 1, 2023, manufacturers and importers must, with narrow exceptions, have such products certified by an accredited third party, and a business selling plumbing supplies, other than a manufacturer, may not sell solder or flux that is not lead free. Products used exclusively for non-drinking-water purposes are exempt if they are labeled, physically incompatible or marketed solely for other uses.

Do you need a permit to replace an air conditioner or furnace in Baltimore City?

Yes. Baltimore City’s Building, Fire, and Related Codes require a permit before any HVACR work, issued only to an HVACR contractor licensed to do business in the City and registered in the City’s E-Permits system; in one- and two-family homes only portable appliances and small self-contained systems are exempt. Fees are low, about $57 for a three-ton heat pump replacement including the application fee and the 5% permit tax, while work done without a permit carries a surcharge of at least $1,000.

What does HVAC distribution and B2B e-commerce software cost?

The distribution ERPs common in this trade, including Epicor Eclipse and Prophet 21, Infor CloudSuite Distribution and DDI System Inform, do not publish prices for their online store modules. Of the general platforms, Microsoft Business Central lists $80 to $110 per user per month, Shopify Plus starts at $2,300 a month on a three-year term and is needed for unlimited B2B price catalogs, and BigCommerce puts customer price lists on its Performance plan from $1,499 a month. For a two-branch supply house moving $9.8 million of orders online, card processing alone costs more than any of those subscriptions.

Should a supply house build a custom online store or use its ERP’s module?

Use the ERP’s module, or a general platform, if it can store licenses and refrigerant certificates on accounts and enforce them at checkout, track equipment by serial number with manufacture and import dates, record the job type on an order line and build matched systems with AHRI numbers and utility discounts. Build a custom layer around the existing ERP when those rules live in spreadsheets or in the counter staff’s memory, which is where most of them live today. Either way, the ERP, accounting and payments should stay.