Buying & hiring
How to read an HVAC quote (tonnage, SEER2, ductwork, warranty)
Three quotes for the same house can differ by thousands of dollars and still not be comparable. Here is what each line should say and what to ask when it does not.
Get at least three, and make them comparable
Prices for the same job vary widely between contractors because of different equipment, different scope and different overheads. Three written quotes are the usual minimum. To compare them, each must describe the same job; where they differ, ask each contractor to price the others’ option, or note the difference and value it yourself.
What every quote should list
| Line | What it should say | Why it matters |
|---|---|---|
| Equipment | Brand, full model numbers of the outdoor unit, indoor coil or air handler, and furnace | Lets you look up the AHRI-matched rating |
| Size | Tons for cooling; input and output BTU for a furnace | Check against the load |
| Efficiency | SEER2 and EER2 for the matched system, HSPF2 for a heat pump, AFUE for a furnace | The rating depends on the matched pair |
| Load calculation | Manual J, or at least the method used | Size should come from the house, not the old unit |
| Ductwork | Reuse, seal, modify or replace, and which parts | Often the largest difference between quotes |
| Electrical, gas, venting | Any new circuit, disconnect, gas line or vent pipe | Hidden extras later |
| Thermostat | Model, and whether it is included | Matters for two-stage and heat pump control |
| Permit and inspection | Who pulls it and whether it is in the price | Required in most jurisdictions |
| Removal | Old equipment and refrigerant recovery | Required by EPA rules |
| Warranty | Equipment parts years, labour years, registration requirement | Labour is where the cost of a failure lies |
| Price and payment | Total, deposit, schedule, rebates assumed | Avoid large deposits |
Check the size
The size on the quote should come from the house, not from the old equipment’s nameplate. Ask for the load calculation. A first estimate from the central AC size calculator tells you whether a proposed size is in the right range: for a 1,500 sq ft house in climate zone 4 with average insulation, about 31,600 BTU per hour, so 3 tons. If the quote says 4 tons, ask why.
The “Is my AC the right size?” calculator applies the ACCA Manual S limits: 115% of the load for an air conditioner, up to 125% for a heat pump in a cold climate, 140% for a furnace. The guides to sizing an air conditioner and to oversized systems explain why a bigger unit is not a safer one.
Check the efficiency
Air conditioners and heat pumps are rated as a matched system: outdoor unit plus indoor coil or air handler. The same outdoor unit can have a different SEER2 with a different coil. The AHRI directory, run by the industry’s certification body, lists the rated SEER2, EER2 and HSPF2 for each matched combination; ask for the AHRI reference number and check it. A quote that lists only the outdoor unit’s “up to” rating may not deliver it.
The SEER upgrade savings calculator turns a difference in rating into dollars. Replacing an old SEER 10 unit with a SEER2 15.2 unit saves about $290 a year on a 3-ton system running 1,200 full-load hours at 17 cents. Going from 15.2 to 18 saves much less, so compare the price difference between tiers with the saving.
Check the ducts
Ductwork is where quotes differ most, and it matters most to how the system performs. A good quote says whether the contractor will measure static pressure and airflow, seal accessible joints, and correct undersized returns. A quote that reuses the ducts without looking at them may be the cheapest and the worst. The guides to duct leakage and return air explain what to look for.
Check the scope and the extras
Look for the things that can turn into change orders: a new pad, a new disconnect or circuit, a condensate pump, a line set replacement (often necessary when changing refrigerant type), a new vent for a condensing furnace, and the permit. The HVAC system replacement cost calculator shows a typical range for the job, so you can see whether a quote is in line before you read the details; the guide to what HVAC installations cost gives the sources.
Warranties
Manufacturers’ parts warranties are typically 5 to 10 years, often requiring the equipment to be registered within 60 or 90 days of installation; ask the contractor to register it and send you the confirmation. The parts warranty does not cover labour, which on a compressor or coil replacement can be most of the cost. A contractor’s labour warranty of one to two years is common; longer ones are worth something, if the contractor will be in business to honour them.
Commissioning
Ask what the installer will measure and record on the day: refrigerant charge by superheat or subcooling, airflow or temperature split, static pressure, gas pressure and temperature rise for a furnace. A quote that includes a commissioning sheet is a sign of a careful contractor.
Red flags
- A price given over the phone without seeing the house.
- No load calculation, or a size taken from the old unit.
- Pressure to sign today for a discount.
- A large deposit before any equipment is delivered.
- A model number that does not appear in the AHRI directory with the stated rating.
A note for contractors and publishers
Contractors, supply houses and energy-efficiency programs can put any of this site’s sizing and cost calculators on their own site from the embed page, so customers can check a size before the visit.