How to Write an HVAC Estimate

Repair estimate or replacement proposal?

Treat these as two different documents. A repair estimate answers one question: what failed, and what does it cost to fix? A replacement proposal answers several: what size system the house needs, which matched equipment you're offering, what the install includes, what's guaranteed and what it costs. Put both on the same form and replacement bids shrink to a model number and a price.

A repair estimate should fit on one screen and be easy to approve on the spot:

• Findings: the failed component, the reading or test that showed it, and a photo when it helps.
• The fix: parts and labor, plus the refrigerant type and the amount you expect to add if the system needs a charge.
• Price: flat rate or time and materials, set the way how to price HVAC jobs describes.
• Repair warranty: what it covers and for how long.
• Expiration: how long the price holds.

When a repair is expensive compared with what the old system has left in it, give the customer both on the same visit, each complete and clearly labeled. The rest of this guide covers the replacement proposal.

Start from the load calculation

The proposal should show where the equipment size came from, and the answer should be a load calculation, not the nameplate on the unit coming out.

Three ACCA manuals divide residential design into steps. Manual J calculates the home's heating and cooling loads. Manual S selects and sizes the equipment from those loads using the manufacturer's performance data. Manual D designs the duct system ¹. ACCA notes that load calculations done to Manual J are required by national building codes and by most states and municipalities ¹, so find out what your building department wants to see at permit time.

On the proposal, a short design basis block is enough:

• The heating and cooling loads from Manual J, in Btu per hour, and the date of the calculation.
• The capacity selected under Manual S for each option.
• Duct findings: whether the existing ducts can carry the airflow the new equipment needs, and any Manual D changes included in the price.

ACCA publishes residential system design review forms, with filled-in examples, for documenting the J, S and D work ², and it has released videos to help code officials and contractors verify code compliance with all three manuals ³. Filling in the form on every replacement gives you a document for the permit application and shows the customer the size wasn't a guess, which matters most when your bid is a different size from the others on the kitchen table. The Manual J load calculation entry explains what goes into one.

Name an AHRI-matched system and attach the certificate

Efficiency ratings belong to a combination of indoor and outdoor equipment, not to the condenser alone, so the proposal has to name the whole match.

AHRI's directory lists a certified matched system as an indoor and outdoor unit combination and gives each one a unique Certified Reference Number. From that listing, the directory generates an AHRI Certificate of Product Ratings showing the system's certified ratings, which you can print and give to the customer ⁴. Manufacturers and wholesalers list the reference numbers for their matched systems in their product catalogs, so ask your distributor for the number when you build the quote ⁴.

For every option, list:

1. Outdoor unit model number.
2. Indoor coil or air handler model number.
3. Furnace model number, when the certificate lists one.
4. The AHRI Certified Reference Number, with the printed certificate attached.

The certificate protects you as much as the customer. The directory's Verify Certificate feature confirms that a printed certificate and its ratings are authentic ⁴, so a homeowner comparing bids can check the exact numbers you quoted instead of a brochure's range.

Two situations need a sentence in writing:

• Reusing the existing coil. A new outdoor unit on an old coil has certified ratings only if that exact combination is listed. If it isn't, don't print a rating for it.
• Substitutions. If a supply problem forces a different model after the customer signs, the reference number changes and the ratings may too. Add a clause that any substitute will carry equal or better certified ratings and that you'll tell the customer in writing before installing it, and handle any price difference as a change order.

Quote the efficiency ratings that apply

Print the ratings from the certificate in the metrics DOE uses now, and check each option against the minimum where the system will be installed.

Since January 1, 2023, DOE's standards for central air conditioners and heat pumps have used SEER2, EER2 and HSPF2, metrics DOE created because the test procedures changed to better reflect real-world installation and use ⁵. The nationwide minimums include 13.4 SEER2 for split-system air conditioners, and 14.3 SEER2 with 7.5 HSPF2 for split-system heat pumps ⁵. Air conditioners also have regional standards: a split-system AC installed in the Southeast or Southwest needs 14.3 SEER2 below 45,000 Btu per hour and 13.8 SEER2 at 45,000 Btu per hour and up, compared with 13.4 SEER2 in the North ⁵⁶. If you work in those regions, your lowest-priced AC option has to clear the regional minimum, not just the national one.

Two habits keep the ratings honest. Quote the certified rating of the match you're installing, never the top number in the product line. And if you estimate operating-cost differences between options, show the assumptions (utility rates, how the house is used) and label the result as an estimate. The SEER2 entry covers what the rating does and doesn't tell a homeowner.

Name the refrigerant and date the price

In 2026 you may be quoting two refrigerant generations side by side, and the proposal should say which one each option uses.

EPA's Technology Transitions rule under the AIM Act sets a global warming potential (GWP) limit of 700 for refrigerants in new residential and light commercial air conditioning and heat pump systems ⁷. A final rule EPA issued on May 26, 2026 removed the installation deadline for systems whose specified components were all manufactured or imported before January 1, 2025 ⁸⁹. EPA proposed that change to allow continued sell-through of existing R-410A equipment, after shortages, price spikes and stockpiling of R-454B during the spring and summer of 2025 ¹⁰.

What that means on paper:

• Name the refrigerant on every option, for example R-410A or R-454B, so a customer comparing bids knows what they're comparing.
• If an option uses R-410A equipment built before 2025, say so plainly.
• Refrigerant prices can spike, as R-454B's did in 2025, so every proposal needs an expiration date and a sentence on what happens to the price if equipment has to be reordered after that date.
• On repair estimates, show the refrigerant type and quantity as their own line so the customer approves the charge before you add it.

Line items a replacement proposal should list

Itemize the scope even if you price each option as one number. The scope list is what makes your bid comparable with others and what settles questions after the install.

Write "existing, reused" when an item stays rather than leaving the row off. A missing line set row reads as "included" to a customer and as "not included" to you. Who may do the electrical portion of an HVAC install depends on your state's licensing rules, so check with your state board before you quote that work as yours.

Exclusions are line items too. Name the ones that cause arguments: patching drywall or ceilings where you open access, electrical panel upgrades unless listed, removal of any hazardous material found, and duct damage hidden behind finished surfaces. State that anything found after the old equipment comes out will be priced and approved before work continues.

Example: One option on a hypothetical heat pump replacement, with round placeholder prices:

Line item	Price
Heat pump and matched air handler (AHRI certificate attached)	$7,000
New line set, pad and disconnect	$900
Thermostat	$300
Duct transitions and sealing	$600
Removal, refrigerant recovery and haul-away	$400
Installation labor, start-up and commissioning	$2,300
Permit and inspection	$300
Total	$11,800

If you'd rather not price each line, show the same list with only the $11,800 total. The customer still sees what the price buys.

Permits and inspections

Give the permit its own line and say who handles it. Whether a change-out needs a permit, which trades it covers and what the inspector checks are set by your local building department, so build your template around your jurisdiction. On the proposal, state:

• The permit fee, either included in the price or passed through at cost.
• That you apply for the permit and schedule the inspection.
• Who needs to be home for the inspection.
• What happens if the inspector calls out an existing condition that wasn't in your scope: you price the correction and get it approved before doing it.

If the permit application needs load calculations, submit the same Manual J you summarized in the proposal so the two documents agree.

Warranty terms: the manufacturer's parts and your labor

A proposal that says "10-year warranty" hasn't said anything useful yet. Who backs what, for how long, and on what condition?

Read the manufacturer's warranty document for the exact model you're quoting, and check whether the longer parts coverage depends on registering the equipment within a deadline. If it does, the proposal should name who registers it and by when; doing it yourself removes the risk that the customer misses it. Record serial numbers at the install and finish the registration before or with the final invoice, as how to invoice HVAC jobs explains.

Your labor coverage is your workmanship warranty, and every callback under it is labor you aren't billing, so price the term you offer. If it depends on annual maintenance, say so on the proposal, not in a letter after something fails.

Rebates and incentives: conditional, separate and dated

Show the full price first. List incentives underneath as things the customer may qualify for, never as a discount already taken.

Start by cleaning out old templates. The federal energy efficient home improvement credit (section 25C), which covered qualifying heat pumps and central air conditioners, is not allowed for property placed in service after December 31, 2025 ¹¹. A proposal for a system installed now should not promise it. Send tax questions to the customer's tax professional rather than answering them on your estimate.

For utility, state and local programs:

• Name the program and the requirement that applies (efficiency level, equipment type, pre-approval, participating contractor).
• Say who files the paperwork and when.
• Use "may qualify," say that approval is the program's decision, and state that the price doesn't change if the rebate is denied.
• Keep the AHRI certificate in the job file in case the program asks for the matched system's details.
• Date the section. Programs change and close, and a proposal can sit on a counter for weeks.

Lay out options in one comparison table

Two or three options in one table let the customer compare like with like. Keep the load calculation, scope and exclusions the same across options so the table shows only the real differences: equipment type, staging, ratings, refrigerant and warranty. Build the tiers from genuine equipment differences, not by padding the top option; good-better-best pricing covers building tiers honestly.

Example: Three options for the same hypothetical house, all sized from one Manual J calculation. Ratings and prices are placeholders, not product data:

	Option 1	Option 2	Option 3
System	Single-stage heat pump	Two-stage heat pump	Variable-speed heat pump
SEER2 / HSPF2	14.3 / 7.5	16.0 / 8.0	18.0 / 9.0
Refrigerant	R-454B	R-454B	R-454B
Labor warranty	2 years	5 years	10 years
Price	$10,000	$12,000	$15,000
Step up		+$2,000	+$3,000

The step-up row does the subtraction for the customer: $12,000 minus $10,000 is $2,000, and $15,000 minus $12,000 is $3,000. A $2,000 step is easier to weigh than two five-figure totals.

If one option needs work the others don't, such as a different thermostat for the variable-speed system, list it in that option's column so the comparison stays fair.

The signature page

The last page turns the proposal into a contract. Keep it plain:

• The option chosen, its price and a reference to the scope list.
• The deposit and when the balance is due. Check whether your state limits deposits on home improvement work; contractor deposits covers the rest.
• The expiration date and the substitution clause.
• The rule for conditions found after removal: priced and approved in writing before the work.
• Any cancellation notice the law requires. If you sign proposals in the customer's home, check whether the FTC Cooling-Off Rule and your state's home solicitation rules apply.
• Signatures and dates for both sides.

Before you send it

• Every option has model numbers, an AHRI reference number, an attached certificate and its refrigerant.
• The ratings match the certificates and meet the minimum for the install region.
• The load calculation basis is stated.
• Every line item is addressed, even if the answer is "existing, reused."
• Parts and labor warranties are separate, with registration responsibility named.
• Rebates are conditional and dated, with no federal 25C credit promised for a 2026 install.
• The proposal has an expiration date.