The 10-Point HVAC Contractor Vetting Checklist

The checklist

1. Verify the Maryland HVACR license on the state's public lookup — the number should be on the quote. (Ours: MD HVAC Master License #78268.)
2. Ask for certificates of insurance — general liability and workers' comp. Uninsured labor on your property is your risk.
3. Require a Manual J load calculation for any replacement — if they size the system "by what's there now," walk.
4. Get an itemized, flat-rate quote: equipment model numbers, scope, permits, and commissioning listed separately. "Whole job: $X" hides omissions.
5. Confirm permit handling where your county requires one. Not every jurisdiction does (Baltimore County has no mechanical permits), but where a permit applies the contractor should pull it — in their name, not yours.
6. Ask how they commission the system: measured airflow, static pressure, refrigerant charge. If the answer is "we turn it on and check it cools," that's not commissioning.
7. Check both warranties: manufacturer parts warranty (usually requires registration — ask who registers it) and the contractor's own labor warranty, in writing.
8. Read recent reviews for patterns, not scores — repeated mentions of callbacks, no-shows, or surprise charges matter more than one angry outlier.
9. Ask what happens if something goes wrong — response time for warranty calls, and whether emergency service is available after install.
10. Trust the pressure test: a contractor who won't leave a quote with you for a few days without a "today-only price" is selling urgency, not value.

Why this matters more than brand

Industry field studies consistently show installation quality affects real-world efficiency and equipment life more than the nameplate on the box. The best equipment badly installed is worse than mid-tier equipment installed right.

Failure mode: vetting by price alone

The cheapest quote usually omits one of the items above — most often permits, commissioning, or insurance. You don't save that money; you defer it, with interest, to the first failure.

Verifying a Maryland licence yourself

HVAC contractors in Maryland are licensed by the state, and licence status is publicly verifiable — you do not have to take anyone's word for it, including ours. Ask for the licence number, then confirm it is current and that the name on it matches the company you are actually contracting with.

That last part matters more than it sounds. A salesperson representing a company that subcontracts the work to an unlicensed crew is a real pattern. Ask directly who will be performing the installation and whether they are employees.

Ask for a certificate of insurance covering both liability and workers' compensation, sent from the insurer rather than a photocopy. If someone is injured on your property working for an uninsured contractor, that exposure can land on your homeowner's policy.

The questions that separate real contractors from order-takers

1. "Will you perform a load calculation?" The correct answer is yes, and the sizing should come from that rather than from the nameplate on the old unit. "We'll match what you have" means nobody is checking whether what you have was ever right.
2. "Will you measure static pressure?" This is how a contractor finds out whether your duct system can support the equipment being proposed. Skipping it is how a correctly sized system underperforms.
3. "What is included if the ductwork turns out to be inadequate?" You want this answered before installation day, not during.
4. "How do you commission the system?" Charge verification, airflow measurement, and control configuration should be named steps, not assumed.
5. "What does your labour warranty cover, and for how long?" Manufacturer parts warranties are broadly similar between brands. Labour warranties are where companies actually differ.
6. "Who handles permits?" The answer should be specific to your county.

Warning signs worth walking away from

• A quote produced without anyone looking at the equipment or the ducts. A price over the phone is a price for a house nobody has seen.
• Pressure tied to a deadline. "This price is only good today" is a sales technique, not a business constraint.
• A large deposit demanded up front. A reasonable deposit is normal; most of the money should follow the work.
• Refusal to itemise. A single number with a brand name cannot be compared to anything.
• Scare tactics without evidence. A cracked heat exchanger is a serious finding — and a serious finding should come with photographs and a clear explanation, not just an urgent recommendation.
• No written scope. Verbal assurances about what is included have a way of evaporating.

Reading reviews without being fooled by them

Volume and star average are weak signals. More useful: read the negative reviews specifically, and look at how the company responded. Every contractor with real volume has unhappy customers; what distinguishes them is whether complaints get addressed or argued with.

Look for reviews that describe the situation in enough detail to be real, and weight recent ones more heavily than old ones — ownership and crews change. Reviews that mention callbacks, warranty service, or how a problem was resolved tell you far more than a five-star review that says "great service."

Comparing the quotes once you have them

Line the quotes up by scope before you look at price. Confirm each names the same equipment class and capacity, and check whether the indoor and outdoor components are matched. Note which quotes include duct work, electrical work, permits, and commissioning, and which are silent on them — silence usually means excluded.

If one quote is dramatically lower, find out what it leaves out. Sometimes the answer is that the contractor has a lower cost structure, which is fine. More often the answer is a narrower scope, and the difference reappears later as a change order or as a comfort problem the new equipment was never going to fix.

What happens after the sale is the real test

Most of the vetting advice available online stops at the point of signing, which is precisely where the differences between contractors start to show. Three things are worth asking about explicitly before you choose.

Callback policy. If the system is not performing as expected two weeks after installation, what happens? A company confident in its commissioning will answer this without hedging.

Warranty administration. Manufacturer warranties usually require registration within a limited window and, in many cases, documented maintenance. Ask who registers the equipment and whether you get a copy. A warranty claim that fails on paperwork years later is a genuinely common and entirely avoidable outcome.

Service continuity. Will the company that installed the system still service it? Some outfits sell installations and subcontract service, which becomes your problem the first time something needs attention.

None of these questions is adversarial, and any contractor worth hiring will have ready answers. The reaction to being asked tells you nearly as much as the answers do.

Next steps

Use the checklist on us: request a quote and ask for every item above. To walk in informed, read what installation should cost in Baltimore and what the efficiency ratings mean. Comparing system types first? Start at heat pump vs. gas furnace.