HVAC Questions to Ask
For homeowners getting quotes on a new system, a repair or a maintenance plan. The questions cover how the contractor sized the equipment, what the ductwork needs, which efficiency ratings are worth paying for, and what the quote and warranty actually include.
The questions
Open any question for the note
What size system does this house need, and how did you arrive at that number?
Why ask it
A real answer references a Manual J load calculation done for this house. Sizing from the old unit's tonnage or from square footage alone is how oversized systems get sold, and oversized systems short cycle, leave the air humid and wear out early.
Which efficiency ratings are worth paying for in this climate?
Why ask it
The premium for top tier SEER2 and HSPF2 equipment only pays back where the system runs many hours a year. A contractor recommending the highest ratings without mentioning run hours is selling rather than calculating.
Which models are you proposing, and why those?
Why ask it
You want reasons about parts availability, local service and what they install most often. 'It is the best brand' cannot be checked; a model number lets you look up the specifications yourself.
What will you do about the existing ductwork?
Why ask it
Duct leakage and undersized returns cap what any new unit can deliver. A quote that touches only the equipment often leaves the original comfort complaint exactly where it was.
What is included in this price, and what gets billed separately?
Why ask it
Permits, the condenser pad, a new line set, electrical work, the thermostat and drywall repair are the usual extras. Ask which of those are inside the number in front of you.
What do the equipment and labour warranties each cover, and for how long?
Why ask it
Equipment warranties often require registration within a set window and proof of annual maintenance. Labour cover is usually the shorter of the two, and it is the part you are most likely to need.
What does a maintenance visit actually include?
Why ask it
Ask what gets done, not how often. A plan that is a filter change and a look around is worth far less than one that includes coil cleaning, drain clearing and a refrigerant charge check.
What refrigerant does this system use, and what happens to the old refrigerant?
Why ask it
Recovery is a legal requirement rather than a courtesy. The refrigerant type also matters long term, because a system on a refrigerant being phased down gets more expensive to service as it ages.
Will my current thermostat work with this system?
Why ask it
Variable speed and communicating systems often need the manufacturer's own thermostat and an extra conductor in the wall. Finding that out after installation is how people end up with a wall patch and a device they did not choose.
Which air quality add-ons make sense here, and which would you skip?
Why ask it
A contractor willing to talk you out of one thing is more believable on the rest. Filtration, ventilation and humidity control solve different problems, so being sold all three suggests none of them was diagnosed.
Which rebates or tax credits does this equipment qualify for, and who files the paperwork?
Why ask it
Eligibility usually depends on the exact model and on installation details, and some utility rebates must be submitted by the contractor. Ask for the qualifying model number in writing before you sign.
How long should this system last here, and what usually fails first?
Why ask it
Answers that name a specific part, such as the compressor or the evaporator coil, come from experience with that model. A flat 'twenty years' is a sales figure.
Who will be on site for the install, and are they your employees or subcontractors?
Why ask it
Installation quality causes more failures than equipment quality. If crews are subcontracted, ask who you call for a warranty visit and whose name is on the paperwork.
How long will the install take, and will we be without heating or cooling overnight?
Why ask it
A one-day swap becomes a two-day job as soon as ductwork or electrical work is involved, which matters a great deal in a heatwave or a hard freeze.
What static pressure did you measure on the existing system?
Why ask it
This separates contractors who measure from contractors who estimate. High static pressure means the ducts cannot carry the airflow the new unit needs, and no equipment upgrade fixes that.
Is a variable speed or two stage system worth it for this house?
Why ask it
The comfort gain is real in humid climates and in houses with rooms that never match. The trade-off is cost and more electronics to fail, so ask what those repairs cost out of warranty.
If some rooms stay uncomfortable after the install, what is the plan?
Why ask it
Settle this before the crew leaves. Answers involving balancing dampers and airflow measurement are workable; 'we can add zoning later' is a second project you have not budgeted for.
What noise levels should I expect indoors and at the outdoor unit?
Why ask it
Sound ratings are published per model and matter for bedrooms and close lot lines. Ask where they intend to put the condenser relative to windows and the neighbour's wall.
What if the load calculation calls for a smaller unit than I expected?
Why ask it
Homeowners tend to assume bigger is safer and contractors often accommodate that to avoid an argument. Saying up front that you want the calculated size makes it easier to get one.
What is the payment schedule, and what has to be finished before the final payment?
Why ask it
Tie the last payment to a passed inspection and a completed startup report. A deposit-heavy schedule with no completion condition leaves you no leverage on the punch list.
Getting a Comparable Quote
Practical guidance for the conversation itself
Before anyone comes out
- Write down the actual complaint: which rooms, at what time of day, in which season. 'The upstairs is eight degrees warmer by afternoon' gets a better diagnosis than 'we need a new system'.
- Find the model and serial number of the existing equipment and its install date. Age changes the repair-versus-replace conversation.
- Check your utility's rebate page yourself before the visit, so you know what is on offer independent of what you are told.
- Note whether you have had duct or insulation work done. A house that has been air sealed usually needs a smaller unit than the one it currently has.
- Decide whether you want a like-for-like replacement or a chance to fix comfort problems, and say which at the start. They are different jobs and different prices.
Reading and comparing quotes
- Insist on model numbers for the outdoor unit, indoor coil and air handler or furnace. Systems are matched, and a cheap quote often pairs a good condenser with a mismatched coil.
- Compare the same efficiency tier across bids. Two quotes that differ by thousands are usually not quoting the same equipment.
- Look for line items on permits, condensate handling, electrical work and duct modifications. Their absence is not a discount; it is a later invoice.
- Ask each contractor for the load calculation output, not just the resulting tonnage. If nobody will produce one, that is the finding.
- Take two or three quotes, not five. Beyond that the numbers stop being comparable and the decision gets harder rather than clearer.
Signs of a careful contractor
- They spend time in the attic, basement or crawlspace before quoting anything.
- They measure static pressure and look at return sizing rather than only counting supply registers.
- They recommend against something you asked about, and explain why.
- They put the startup readings in writing: refrigerant charge, temperature split, airflow.
- They mention the permit and inspection without being asked, and they pull it themselves.
What to keep once the work is done
- The startup and commissioning sheet with measured readings, which is the only evidence the system was set up correctly.
- Warranty registration confirmation, since many manufacturers shorten cover if registration is missed.
- The permit and passed inspection record, which a buyer's inspector will look for later.
- A photo of the equipment labels and the thermostat wiring before the panels go back on.
- The maintenance schedule in writing, including what is required to keep the warranty valid.