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Estimates and invoices for HVAC companies, from the repair call to the new system.
A repair is a price. A replacement is a decision, and the customer wants to compare. Both go wrong when something is found once the old unit is open. Here is how to write them so they hold up.
By Abrar · Updated · 8 min read
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The short answer
An HVAC replacement has a high price, a deposit, a cancel window in some states, and often a part nobody saw until the old unit came out. Write each option as its own estimate, list every part and what is repaired or replaced, and put each found extra on a change order signed before the work. InvoiceWren holds the estimate, the changes, the deposit and the payments on one job.
How an HVAC job runs on paper
A repair call and a replacement follow the same path, with different amounts of money. The steps below are in the usual order.
- 1
The call
No cooling, no heat, a maintenance request or a replacement inquiry. Write down the address, the system type and the symptom.
- 2
The diagnosis
The technician inspects the system and records what is found. A yearly check covers things like the coils, the refrigerant level and the filters. ENERGY STAR suggests checking cooling in the spring and heating in the fall [1].
- 3
The estimate
For a repair, a line-item price. For a replacement, often two or three options, such as a like-for-like system and an upgrade, so the owner can choose. Make one estimate for each option, so the customer signs exactly the one they pick.
- 4
The agreement and the deposit
In states that require it, a written home improvement contract with a down payment and a payment schedule. See the rules below: they differ a lot from state to state.
- 5
The work
The equipment is ordered and installed by a licensed contractor in states that license HVAC. Refrigerant work needs a technician certified under EPA Section 608 [2].
- 6
The extras
A failed line set, a bad thermostat wire, a duct problem. Each is a change with its own price, written and signed before the work starts. California's sample contract says extra work and change orders become part of the contract once they are prepared in writing and signed before the work starts [3].
- 7
The invoice
The contract amount, plus each signed change, less what has been paid.
- 8
The payment and the record
Record the payment, give a receipt, and write down the work done and the equipment installed. You will want it at the next service call.
Where HVAC paperwork goes wrong
These come mostly from the big jobs: a deposit, a new unit, a part nobody priced.
Extra work on a spoken yes
The technician finds more to fix, does it, and the owner disputes the bill. California's sample contract says extra work and change orders become part of the contract once they are in writing and signed before the work starts [3].
What to do: A change order with the scope, the amount, and its effect on the payments, signed before the extra work starts.
A deposit larger than the law allows
A replacement contract asks for half up front. In California the down payment may not exceed $1,000 or 10 percent of the contract price, whichever is less [4].
What to do: Write a payment schedule that names each phase and its amount. Check your state's home improvement law before you set the deposit.
A quote that does not say what is included
The owner thinks the quote covers the line set, the pad and the permit. The quote says "install new unit". At the end the extras are a surprise.
What to do: List each part: outdoor unit, coil, air handler, line set, pad, thermostat, permit and haul-away. Say what is repaired and what is replaced.
Work without the right license or certification
Texas says contractors who install, repair or maintain air conditioning, refrigeration or heating systems must have a license from the state licensing department [5]. EPA says technicians who maintain, service, repair or dispose of equipment that could release refrigerants must be certified [2].
What to do: Put your license number and your technicians' certification on the estimate and the invoice.
The customer cancels after you ordered the equipment
California's sample contract says the buyer has the right to cancel within three business days [3]. New York says the customer has an unconditional right to cancel until midnight of the third business day [6].
What to do: Give the cancel notice your state requires. Do not order special equipment before the window ends.
A maintenance visit with no written scope
The owner expects more than a tune-up covers, or less. ENERGY STAR's checklist includes cleaning the evaporator and condenser coils and checking the refrigerant level [1].
What to do: List the items you check and do on the visit invoice.
What InvoiceWren does for an HVAC company
A phone in the utility room is enough to keep the options, the changes and the payments straight.
One estimate for each option
Make an estimate for the like-for-like replacement and another for the upgrade. Your customer reads both on their phone and signs the one they choose.
Saved items for the parts you quote every week
Save the line set, the pad, the thermostat, the permit pass-through and the haul-away. Each takes a tap on the next estimate.
Photos on the line they belong to
Add up to 3 photos to a line. A photo of the cracked line set sits beside the line that prices it.
Change orders signed before the work
Found a failed part with the old unit out? Send a change order. Your customer approves it on their phone, and it is not counted as approved until they do.
A deposit, then a balance that adds up
Send a deposit invoice from the approved estimate. The final invoice shows the estimate, each approved change and each payment, line by line.
Paid by Zelle, bank transfer or your own link
Your customer pays you directly and we take no fee. They tap "I've paid", you check your account and confirm, and the receipt goes out.
Reminders that stop when they pay
If an invoice is late, InvoiceWren emails your customer for you. You choose the schedule, and it stops once you confirm the payment.
Estimates and approval · Change orders · Deposits, progress and final invoices · Getting paid and receipts
Need a document right now? Make a free estimate or a free invoice with no sign-up, then bring the job into InvoiceWren when you are ready.
Rules to check, by state
HVAC is licensed by the state, and the refrigerant rules are federal. These are examples from official pages we read on Nov 13 2026. They are not every rule. Check yours.
- Federal: EPA says technicians who maintain, service, repair or dispose of equipment that could release refrigerants into the atmosphere must be certified under Section 608 [2].
- Federal: EPA says homeowners can maintain and repair their systems throughout the useful life of the equipment [7]. The rules for refrigerants in new systems have been changing, so check EPA before you quote a replacement.
- California: the down payment may not exceed $1,000 or 10 percent of the contract price, whichever is less [4]. Extra work and change orders must be in writing and signed before the work starts, and the buyer has the right to cancel within three business days [3].
- Texas: contractors who install, repair or maintain systems related to air conditioning, refrigeration or heating must have a license from the state licensing department [5].
- New York: the state requires a written contract for home improvement work, and the customer has an unconditional right to cancel until midnight of the third business day. Home improvement contractors must be licensed in New York City and in Suffolk, Nassau, Westchester, Putnam and Rockland counties [6].
- ENERGY STAR: check the cooling system in the spring and the heating system in the fall. Its checklist includes cleaning the evaporator and condenser coils and checking the refrigerant level [1].
This is general information, not legal or tax advice. We did not read an official page on sales tax for HVAC work, so ask your state tax office.
Checklist
Questions
Can I ask for half down on a replacement?
It depends on the state. In California the down payment may not exceed $1,000 or 10 percent of the contract price, whichever is less [4]. Check the home improvement law where you work.
Do I need a written change order for extra work?
In California, extra work and change orders become part of the contract once they are written and signed before the work starts [3]. In other states it is still the safest way. In InvoiceWren you send the change order and the customer approves it on their phone.
Do I need a license to do HVAC?
In Texas, yes: contractors who install, repair or maintain air conditioning, refrigeration or heating systems must have a license from the state licensing department [5]. Other states differ, so check yours.
What certification do I need to work with refrigerant?
EPA Section 608 certification, for technicians who maintain, service, repair or dispose of equipment that could release refrigerants [2].
Can I still repair an older system?
EPA says homeowners can maintain and repair their systems throughout the useful life of the equipment [7]. The rules for new equipment have been changing, so check EPA before you quote a replacement.
How do I give a customer two or three prices?
Make one estimate for each option. The customer signs the one they choose, and the others stay unsigned.
When can a customer cancel?
Three business days in California [3] and in New York [6], for a home improvement contract. Check your own state.
What should a maintenance visit cover?
ENERGY STAR's checklist includes cleaning the evaporator and condenser coils and checking the refrigerant level, with cooling checked in the spring and heating in the fall [1]. List what you did on the visit invoice.
Send your next estimate from the job.
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Sources
- ENERGY STAR: Maintenance Checklist. Checked .
- U.S. EPA: Section 608 Technician Certification Requirements. Checked .
- California Contractors State License Board: Sample Home Improvement Contract (2025). Checked .
- California Contractors State License Board: Industry Bulletin, Progress Payment Restrictions (Nov 22 2022). Checked .
- Texas Department of Licensing and Regulation: Air Conditioning and Refrigeration Contractors. Checked .
- New York State Attorney General: Home Improvement Fact Sheet. Checked .
- U.S. EPA: Frequent Questions on the Phasedown of Hydrofluorocarbons. Checked .
Prices and features change. We check these pages before each update. If something here is out of date, tell us at hello@invoicewren.com and we will fix it.