How to Compare HVAC Quotes and When to Get a Second Opinion

Two heating and cooling quotes can be compared only when both are written, itemized and describe the same job: the equipment model numbers and the rated indoor and outdoor combination, the efficiency ratings, the load calculation behind the size, the ductwork and refrigerant work, the permit, and the warranty. ENERGY STAR advises signing a written proposal before work starts, and the Federal Trade Commission (FTC) advises confirming the contractor’s license with your state or county. A second opinion is worth the time whenever a first visit ends in a recommendation to replace a major component or the whole system.

What a written proposal should list

The proposal is the document you will rely on later, so it has to be specific. ENERGY STAR advises signing a written proposal before work starts that specifies project costs, model numbers, the job schedule and warranty information, and comparing bids on cost, energy efficiency and warranties.

The FTC’s advice on home repairs is to get three written estimates, and it says a written estimate should include a description of the work, the materials, the completion date and the price.

The FTC adds what the contract itself should contain:

• The contractor’s name, address and license number.
• Start and completion dates.
• Any promises made in conversation, such as the scope of work.
• A written statement of your right to cancel within three business days, if you signed at home or anywhere other than the seller’s permanent place of business.

The FTC also advises making sure all blank spaces are filled in before you sign.

Is it the same system? Model numbers and the rated combination

Federal efficiency rules rate a split air conditioner or heat pump as a certified combination of outdoor unit and indoor coil or air handler. ENERGY STAR’s design report for new homes asks for the AHRI reference number that represents the rated efficiency of the specific combination of indoor and outdoor components.

That number is a direct way to compare two quotes. If both name the same outdoor unit but different indoor coils or air handlers, the certified ratings can differ.

Location matters too. Under federal rules for the Southeast and Southwest, an outdoor unit model with any certified combination rated below the regional standard cannot be installed there (10 CFR 430.32).

Is the size based on a calculation?

Different sizes on two quotes are a reason to ask how each was chosen. The 2024 International Residential Code, Section M1401.3, requires equipment to be sized under ACCA Manual S from loads calculated under ACCA Manual J, or other approved methods.

ENERGY STAR expects a home evaluation as part of the bid: sizing based on the size of the house, the level of insulation and the windows, an inspection of the ducts for leaks and insulation, and a measurement of airflow against the manufacturer’s specifications. A quote built without those steps is not comparable to one built with them.

Refrigerant and the old system

New systems now arrive with new refrigerants, and the proposal should say which one. Since January 1, 2025, new residential systems must use a refrigerant with a global warming potential below 700, such as R-454B or R-32. The exception, under an EPA rule effective July 27, 2026, is an R-410A system in which every specified component was made or imported before January 1, 2025.

The old system’s refrigerant cannot simply be released. EPA prohibits intentionally venting refrigerant while servicing, repairing or disposing of equipment, so the proposal should say who recovers it.

License, certification and insurance

Credentials can be checked before a contract is signed. The FTC advises considering only licensed and insured contractors, confirming the license with your state or county government, and asking for proof of insurance. ENERGY STAR’s first tip is to find out the license and insurance requirements for contractors in your state.

Refrigerant work adds a federal credential. EPA’s Section 608 certification has four types. Type II covers servicing or disposing of high- or very high-pressure appliances, except small appliances and motor vehicle air conditioners; Universal covers all types. EPA states that Section 608 certifications do not expire.

Payment terms

How and when you pay is part of the comparison. The FTC advises:

• Do not pay the full amount up front. Some states limit how much a contractor can ask for as a down payment.
• Do not make the final payment until the work is done and you are satisfied with it.
• Do not pay by cash or wire transfer.

The FTC also lists warning signs: contractors who knock on your door because they are “in the area,” who accept only cash or want everything paid up front, who pressure you to decide on the spot, or who ask you to get the required building permits.

When a second opinion is worth it

A recommendation to replace is the point to slow down. Ask the first contractor to put the finding in writing, with the measurements behind it. ENERGY STAR’s checkup list shows what those measurements can include: the refrigerant level, blower adjustment for proper airflow, electrical connections and the voltage and current on motors, and on the heating side, gas connections, gas pressure, burner combustion and the heat exchanger.

A second contractor can then check the same items and either confirm the finding or explain the difference. Two written reports that measure the same things are easier to judge than two verbal opinions.

When a professional is needed, and what to ask

The whole comparison rests on a few questions put to each contractor in the same words:

• What is the AHRI reference number for the exact combination you are proposing?
• What load calculation did you use, and can I have a copy?
• What will you do to the ducts, and will you measure airflow?
• Which refrigerant does the system use? If R-410A, when were all its components made or imported?
• Who obtains the permit, and when is the final inspection?
• What license do you hold, what EPA certification will the installers have, and can I see proof of insurance?
• What does the warranty cover, for how long, and does the manufacturer’s warranty require registration? Who registers it?