Questions to Ask an HVAC Installer Before You Sign
Two bids for the same house can be far apart, and the gap usually comes from what each installer measured, not from the brand on the box. These 57 questions to ask an HVAC or heat pump installer are for homeowners buying a new central air conditioner, furnace or heat pump, whether the old system just died or the house has never had central air. They run in the order the decision goes: the company, sizing and equipment, heat pump specifics, ducts and airflow, the installation itself, then price and warranty.
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The questions
Each question, and why to ask it
The company
What kind of work makes up most of your business, and how many systems like the one you are proposing did your crew install in the past year?
Why ask it
A company that mostly does commercial rooftop units or service calls may rarely commission a variable speed heat pump in a house. Recent repetitions with the exact equipment class matter more than the number of years on the truck door.
Are you licensed for heating and cooling work in my state or city, and can your insurer send me the liability and workers compensation certificates?
Why ask it
Licensing for heating and cooling work differs by state and sometimes by city, so take the number and look it up with the board that issued it. Certificates should arrive from the insurance agency with current dates rather than as a photo of a card in the glovebox. Ask your own home insurer what an injury to an uninsured worker in your attic would mean for you.
Will your own employees do this install, or is any of it subcontracted, and who is the lead installer on site?
Why ask it
Salespeople rarely install, and some firms hand the job to a rotating crew of subs. Getting a named lead tells you who owns the brazing, the duct connections and the startup numbers when something is off in August.
If something is not right in the first few weeks, who do I call, and is the return visit free?
Why ask it
Installation mistakes tend to show up in the first hot or cold spell: a rattle, a drain that drips, a room that will not keep up. Find out whether the crew that installed it comes back or the job is handed to a service department that bills a trip charge.
Are you an authorized dealer for the brand you are quoting, and where do your parts come from when something fails?
Why ask it
The badge on the cabinet matters less than whether a distributor near you stocks the control board or blower motor in the middle of July. Dealer status can also decide which of the maker's longer warranties the installer is allowed to register for you.
Who on the crew handles the refrigerant, and what certification do they hold for it?
Why ask it
In the United States anyone who opens a refrigerant circuit needs an EPA certification, and other countries run their own schemes, so check how it works where you live. Some of the newer refrigerants are mildly flammable and come with their own training. A certified technician can show the card without going back to the truck.
Can you give me two or three customers from at least three years ago whose systems I can ask about?
Why ask it
A new system feels great for the first month no matter how it was installed. Owners three or four seasons in will tell you about humidity problems, noisy returns, repeat service calls and whether anyone answered the phone.
Sizing and equipment
Does my current system really need replacing, or would a repair buy me a few more years?
Why ask it
The person answering sells new equipment, so listen for specifics: the part that failed, what it costs, the age of the unit and whether its refrigerant is still easy to get. When the case for replacement stays vague, a second look from a company that mostly does service work costs one diagnostic fee.
What did you look at inside my house before writing this quote?
Why ask it
A designed quote takes a walk through the attic or crawlspace, a look at the duct trunks and returns, the electrical panel, and a count of the windows and which way they face. If the number would be the same for the house next door, it was priced, not designed.
Will you run a room by room load calculation, a Manual J, and give me a copy, or are you sizing from square footage and the old unit?
Why ask it
Sizing off the outgoing equipment repeats whatever mistake was made last time, and square footage rules of thumb ignore your insulation, windows and air leaks. An oversized air conditioner runs in short bursts, removes less humidity and can leave the house clammy even at the temperature you set. Manual J is the North American method, so elsewhere ask for the local equivalent.
What did the load calculation assume about my insulation, windows and air leakage?
Why ask it
The inputs are where a load calculation gets padded: every window entered as single pane, the house marked as leaky, a few extra degrees added for comfort. That page of the report is worth reading yourself. If attic insulation or air sealing is already on your list, doing it first can change which size is right.
Why did you pick this model for my house, and what would a two stage or variable speed version change?
Why ask it
The right answer connects your load numbers, duct capacity, humidity and budget to the model on the proposal. If the only justification is a brand relationship or a current promotion, you are being sold inventory rather than a designed system.
Should I be buying a central air conditioner, a heat pump, or a heat pump paired with a furnace, and which would you put in your own house here?
Why ask it
A heat pump is an air conditioner that can also run in reverse, so the cooling half of the quote looks almost the same either way. What decides it is your winter, your gas and electricity prices and the furnace you already own. An installer who only ever quotes one of the three is selling a habit.
Is the indoor coil or air handler an AHRI certified match for the outdoor unit, and what is the rated efficiency of that exact pair?
Why ask it
Efficiency ratings belong to a matched pair, never to the condenser alone, so a coil the maker did not test with it can cost you efficiency and, with some brands, warranty coverage. With the AHRI reference number printed on the quote, you can check the pairing in the public directory yourself. Outside North America, the maker's own matched system tables do the same job.
How long would the higher efficiency model take to pay for itself on my bills?
Why ask it
The US labels are SEER2 for cooling, HSPF2 for a heat pump's heating and AFUE for a furnace, and equipment costs more as each one climbs. In a short cooling season the top tier can take longer to pay back than the equipment lasts. A payback worth trusting is worked out from your own utility rates and run hours.
What refrigerant does this system use, and will it still be easy to service in ten years?
Why ask it
Refrigerants are being phased down in stages, on different timetables in different countries, so the gas in a unit built this year may not be the one in the unit it replaces. A recharge tends to cost more once a refrigerant is no longer made, which is worth knowing before you take a discount on an older model.
Are you replacing the indoor coil along with the outdoor unit, or leaving the old coil in place?
Why ask it
The outdoor unit and the coil above the furnace are two halves of one machine, and a new condenser on the old coil may not share a refrigerant or a rating with it. A quote that keeps the old coil owes you a reason, plus the manufacturer's position on the warranty for that pairing.
How old is my furnace or air handler, and is it worth replacing at the same time as the air conditioner?
Why ask it
Central air uses the furnace's blower, so doing both at once means one day of labor and controls that were made for each other. A furnace with years left is fair to keep, provided its blower can move the air the new coil needs. Having the price both ways on paper makes the choice plain.
Which thermostat does this equipment need, and what do I lose if I keep the one on my wall?
Why ask it
Two stage and variable speed systems often want the maker's own control and an extra wire or two. A generic smart thermostat can reduce an expensive variable unit to plain on and off, which is most of what you paid extra to avoid.
Heat pumps
How much heat does this heat pump put out on the coldest day you designed for, and how much backup heat are you installing?
Why ask it
The headline rating is taken at a mild 47 degrees Fahrenheit, and output falls as the air outside gets colder. The temperature at which the heat pump alone stops keeping up is called the balance point, and everything below it is backup heat. Oversized electric backup is the easy way out for the installer and a usual source of the January bill nobody warned the owner about.
How is the backup heat controlled, and can it run at the same time as the compressor?
Why ask it
Electric strips that are locked out in mild weather and only join in behind the compressor add little to the bill. Strips that switch on whenever the thermostat is a couple of degrees behind can end up doing much of the heating. The telling case is the morning warm-up after a night setback, which is when unrestricted backup usually fires.
Is this a cold climate model, and what is the lowest outdoor temperature it is rated to keep running at?
Why ask it
Standard heat pumps shed output quickly as the temperature drops, while cold climate models are built to hold more of it well below freezing. The evidence is the manufacturer's extended performance table for the exact model, which a heat pump installer should be able to pull up on the spot.
Would you keep my gas furnace as the backup, and at what outdoor temperature would the system switch over to it?
Why ask it
This is a dual fuel setup, and the switchover point should come from your gas and electricity prices and the heat pump's output at that temperature. Left at the factory default, the furnace can end up doing most of the winter. Ask to see the arithmetic for your own rates.
How does this unit defrost, where does the meltwater go, and how high off the ground will it sit?
Why ask it
In heating mode the outdoor coil frosts over and the unit melts it off every so often, with a puff of steam that alarms new owners. That water needs somewhere to drain that is not a walkway, and in snow country the unit belongs on a stand or wall bracket above the usual drift.
What will the air from the vents feel like in winter, and should I run the thermostat differently than I did with a furnace?
Why ask it
Heat pump air comes out warm, not hot, and the system runs in long steady stretches where a furnace blasts and rests. People who are not told this call for service on the first cold night. Settle whether this model does best held at one temperature all day or with a small night setback.
What do you expect my heating bill to be next to what I pay now, and what is that estimate built on?
Why ask it
A fair estimate starts from your past fuel bills, your local rates and the unit's efficiency at the temperatures you really get. Treat it as a range. Be wary of a savings figure that appeared before anyone asked what you pay today.
Should this be a ducted heat pump, ductless heads, or a mix, and how did you decide where each head goes?
Why ask it
One head in a hallway rarely heats bedrooms with the doors shut, and many small heads on a single outdoor unit can run poorly when only one is calling. Placement should follow the room by room loads, not which walls are easiest to reach.
Ducts and airflow
Have you measured the static pressure and airflow on my current system, and what numbers did you get?
Why ask it
The test is two small holes and a handheld gauge, done in minutes, and it shows whether the ducts can move the air the new equipment expects. Without it the bid is a guess about restricted airflow, a common reason an efficient system ends up loud, uneven and hard on its compressor.
Exactly what duct work is included in this bid, and which of my existing runs and returns stay as they are?
Why ask it
Undersized returns and crushed flex runs starve a system no matter how efficient the box is, and duct changes are the easiest line to leave out of a low bid. A written scope names the runs being replaced and the number of returns you end up with.
My house has never had central air: where would the ducts, the air handler and the returns go, and what gets cut open to run them?
Why ask it
Installing central air in a house built without it is mostly a duct job with an air conditioner attached. A sketch of the route should show which closets lose space and which ceilings and floors are opened, and the bid should say who patches and paints afterward.
I have a furnace with ducts but no cooling: were these ducts sized for air conditioning, or only for heat?
Why ask it
Cooling generally needs more air through the same ducts than gas heat does, so a system that heats quietly can turn loud and weak once a coil is added. A straight answer names the trunks or returns that have to grow, and says whether runs through the attic need insulating so they do not sweat.
Will you seal the ducts and test them for leakage, and can I see the numbers before and after?
Why ask it
Ducts leaking into an attic or crawlspace cool a space nobody lives in. A leakage test puts a figure on it, and some building codes require one when equipment is replaced, so ask whether yours does.
What in this proposal fixes the rooms that are too hot or too cold today?
Why ask it
New equipment on the same ducts delivers the same uneven rooms, only more efficiently. The fix is usually dull: an added return, a larger run, a balancing damper. Name the room and have the remedy written into the scope.
What filter setup are you installing, where will I change it, and what size do I buy?
Why ask it
A deep media cabinet beside the air handler is easier on airflow than a thin high rated filter pressed into a return grille. It only helps if you can reach it, so ask to be shown the spot, and write the dimensions down before the crew leaves.
If you are proposing zones, what happens to the airflow when only the smallest zone is calling?
Why ask it
Dampers on single stage equipment push a whole system's air through one zone's ducts, which is noisy and hard on the coil. A bypass duct is a patch for that. Zoning works best with equipment that can turn itself down, and how far this unit can is the number to get.
The install
Are you reusing the copper refrigerant lines or running new ones, and if you reuse them, how are they cleaned?
Why ask it
A lineset carrying old oil or acid from a burned out compressor can kill a brand new one, and a pipe size that suited the old unit may be wrong for this one. Lines buried in finished walls are the ones most tempting to reuse, so a flush and pressure test noted on the invoice is the least to expect when they stay.
How do you make sure the refrigerant lines are dry and leak free before you add the charge?
Why ask it
The careful method is to braze with nitrogen flowing through the pipe, pressure test the joints, then pull a vacuum read on a micron gauge, commonly to about 500 microns, and watch that it holds. Charge is weighed in afterward and checked against the maker's targets. If the gauge never comes up in the answer, ask about it by name.
If this is a gas furnace, will you run a combustion analysis and a carbon monoxide test at startup, and will you write down the readings?
Why ask it
Combustion numbers and a CO reading are what separate a real startup from lighting the burner and listening to it. They also give you a baseline, so a figure that has climbed at a later annual service is an early warning instead of a surprise.
How will the new furnace be vented, and does the old chimney still work for the water heater left behind on it?
Why ask it
A high efficiency furnace usually vents through plastic pipe out a side wall, leaving a gas water heater alone on a flue that was sized for two appliances. That can leave the water heater drafting poorly, so ask whether the chimney needs a liner and who checks the draft afterward.
Where will the outdoor unit sit, how loud is it, and how much room will the next technician have to work on it?
Why ask it
A condenser under a bedroom window or wedged against a fence is a comfort and airflow problem, and sound ratings differ enough between models that the decibel figure for the one quoted is worth asking for. Cramped attic or closet placement raises the labor cost of every repair for the life of the system.
Where does the condensate drain run, and is there a backup pan and a float switch in case it clogs?
Why ask it
Drain lines on attic and closet air handlers grow slime and plug, and the ceiling below is where you find out. A float switch that shuts the system off when the pan fills costs very little next to a ceiling repair that an insurer may argue about.
Can my electrical panel take this equipment, who does any electrical work, and is that in the quote?
Why ask it
Heat pumps with backup heat and larger air handlers often need a bigger breaker, a new disconnect at the unit, or panel capacity you do not have. This is a classic mid job change order, so settle who is responsible before demolition starts.
Who pulls the mechanical permit, who meets the inspector, and is the permit fee in the price?
Why ask it
Whether a like for like swap needs a permit depends on your town, so check with the building department yourself. Where one is required, skipping it saves the contractor a fee and an inspection and leaves the unpermitted work with you when you sell.
How many days will the crew be here, and what happens if the house has no heating or cooling by evening?
Why ask it
A simple changeout is short, while duct changes, a new lineset or panel work add days. Ask what the plan is if a part is missing at four in the afternoon during a heat wave. A good crew has one, even if it is a loaned window unit or space heater.
How will you protect my floors and ceilings during the work, and who hauls away the old equipment?
Why ask it
The crew will carry a coil and a furnace through the house and walk attic joists above your ceilings. Floor runners, the repair if a foot goes through the drywall, and removal of the old unit with its refrigerant recovered should all be in the written scope.
At the end of the job, what measured numbers will you document for me, and who walks me through the thermostat settings?
Why ask it
A real commissioning sheet lists total airflow, static pressure, refrigerant charge with subcooling and superheat, temperature split, and combustion readings on gas equipment. With those figures on paper, the next technician can tell a system that has drifted from one that was never set up right.
Price and warranty
Can you price two or three options on the same load calculation, with full model numbers on each?
Why ask it
Model numbers are what let you look up the matched rating and compare one company's bid with another's. A line that reads three ton, high efficiency system cannot be checked against anything. Seeing the options side by side also shows what each step up buys.
What is left out of this price that I could still end up paying for?
Why ask it
Old equipment removal, refrigerant recovery, duct sealing, electrical, drywall patching, thermostat, filter cabinet, pad, permit and rebate paperwork are the items that turn a low bid into a surprise. Going down that list with each bidder and writing yes or no beside every item is the quickest way to line three quotes up.
What is the payment schedule, and how is a change order priced and approved once the job has started?
Why ask it
A deposit with the balance due after startup is a common arrangement, and some states cap what a contractor may take up front, so look up what applies where you live. A change order should be a written price you sign before the extra work begins, never a figure that first appears on the final invoice.
Which of the add-ons on this quote, such as a UV light, air purifier or surge protector, would you leave off if it were your money?
Why ask it
Accessories are where a salesperson has the most room, and some do more for the invoice than for the air. Have each one priced on its own line next to the problem in your house it is meant to solve. Anything that cannot name one can come off.
Does this exact model qualify for a utility rebate or tax credit where I live, and is that money taken off your price or paid to me later?
Why ask it
Incentives change by year, by utility and by country, and they attach to specific model pairings, so confirm on the program's own site and not only on the quote. An instant discount and a check you wait months for make two bids look alike when they are not.
If I finance through you, what is the rate after the promotional period, and is there a different price for paying outright?
Why ask it
Dealer financing can carry a fee that the contractor pays the lender and folds into the job, which is why asking for a cash price sometimes moves the number. Read what happens to deferred interest if the balance is not cleared in time, and compare the offer with your own bank or credit union.
How long is this price good for, and what could change it before the install date?
Why ask it
A written quote with an expiry date a few weeks out is ordinary. A discount that vanishes when the salesperson leaves the driveway is pressure, and it is fair to say you will call back after the other bids are in.
How long are parts covered, how long is your own labor covered, and who registers the equipment with the manufacturer?
Why ask it
Many manufacturers give their longer parts coverage only if the equipment is registered within a set window after installation, and that step is often forgotten. Labor is a separate promise from the contractor, and its length is one of the biggest real differences between two similar bids.
If the compressor fails in year six, what would I actually pay?
Why ask it
A parts warranty covers the part. The refrigerant, the labor to swap it and the diagnostic visit are usually separate, and on a compressor they add up. Walking through one named failure shows what the labor coverage on this bid is really worth.
What happens to my warranty and service if your company closes or is sold?
Why ask it
Manufacturer parts coverage generally stays with the equipment, so another dealer can file a claim, though the warranty document says whether it passes to a later owner of the house. Labor coverage is different: it may be the company's own promise, which ends with the company, or a plan backed by the manufacturer or an insurer, which comes with paperwork you can keep.
What maintenance does this system need each year, and what does your service plan cost against paying per visit?
Why ask it
Most of it is modest: filters, a rinsed outdoor coil, a cleared drain, a check of the readings against the startup sheet. Find out which parts you can do yourself and whether the warranty asks for proof of professional service.
Hiring an HVAC Installer Without Regret
Practical guidance for the conversation itself
Which Questions Fit Your Job
Replacing a Central Air Conditioner
If you are buying a new central air conditioner because the old one died, start with Sizing and equipment and Ducts and airflow. The old unit's size is the least reliable fact in the house, and the week it fails is when a contractor is most tempted to swap like for like. Skip Heat pumps unless a bid proposes one, and consider asking for that bid anyway so you can see the difference in price.
Installing Central Air for the First Time
Before installing central air in a house with radiators or baseboard heat, treat the ducts as the project. Spend most of the visit on where the air handler and returns would go and what gets opened up, and ask each bidder whether a ductless or small duct system would spare the ceilings. In a house that already has furnace ducts, the thing to settle is whether those ducts can carry cooling.
Hiring a Heat Pump Installer
The Heat pumps group is written for this visit. Ask every heat pump installer for the capacity at your design temperature and the backup heat plan in writing, because those two answers separate a system sized for your winter from one sized for the brochure. Bring a year of fuel and electric bills so the running cost estimate starts from real numbers.
Buying the AC and the Heat Together
When a new AC and heat unit go in on the same day, the furnace or air handler, the coil and the outdoor unit should be quoted as one matched set with one AHRI reference number. Use The install for venting, gas and condensate, which are the parts of a furnace job that an air conditioning bid never mentions.
What a Good Installer Asks You
The conversation should run both ways. Expect to be asked which rooms are uncomfortable, how you set the thermostat, whether anyone in the house has allergies, what your bills look like and whether you plan to add insulation, a room or a car charger. An installer who asks none of it before replacing your air conditioning is quoting the old equipment, not your house.
How to Get Bids You Can Actually Compare
Make the Load Calculation the Entry Fee
Tell every bidder you want a room by room Manual J and a copy of the output. Contractors who size from the old nameplate will often disqualify themselves on the phone, which saves you two hours in your living room and the humidity problems that follow an oversized system.
Ask for the Same Three Numbers From Everyone
Request the AHRI matched pair reference number, the design airflow in CFM, and the measured static pressure on your existing ducts. When one bid is thousands cheaper, those numbers usually show it is a different system, not a better price.
Price the Ducts Separately From the Box
Have each proposal split equipment from duct, return, filter and electrical work. Otherwise the cheapest quote is simply the one that assumed your existing ductwork is fine, and you will pay for that assumption in comfort or in a second job later.
Put Commissioning in the Contract
Write in that final payment follows a startup report with measured airflow, static pressure, charge, temperature split and combustion readings where applicable. Installers who commission properly are happy to sign that. The rest will tell you why it is not necessary.
Handle Rebates and Registration Yourself if Needed
Ask which utility rebates or tax incentives apply to the exact model and who files the paperwork, then confirm the equipment is registered with the manufacturer once it is running. Both have deadlines, and both are worth real money you cannot recover later.
Numbers Worth Knowing Before the Sales Visit
- Sizing: from a Manual J load calculation, not the square footage per ton rules of thumb, which tend to land on a bigger unit than the house needs
- Airflow: roughly 350 to 400 CFM per ton of cooling, lower end in humid climates for better moisture removal
- Static pressure: most residential equipment is rated near 0.5 inches of water column total external, and readings well above that mean a duct problem
- Evacuation: pulled to about 500 microns and holding, verified with a micron gauge rather than a needle on a manifold
- Temperature split: commonly about 16 to 22 degrees Fahrenheit between return and supply air on a properly charged cooling system
- Filter: a 4 inch media cabinet adds far less resistance than a 1 inch high MERV filter squeezed into a return grille
- Heat pump backup: staged and locked out above the balance point, since unrestricted electric strips are what create shocking winter bills
- Warranty registration: a deadline set by the brand, often 60 to 90 days from installation, to get the longer parts coverage, so read the warranty card for yours
- Labor warranty: often 1 year as standard, with 2 to 10 years available and a genuine differentiator between bids
- Deposit: a modest percentage up front, with the balance due after startup numbers are documented
Warning Signs Worth Walking Away From
A Quote Given Without Entering the House
Bids produced from a phone call, a satellite photo or a five minute look at the outdoor unit skip the load, the ducts and the returns entirely. Whatever is wrong with your current comfort will be reinstalled with a newer badge on it.
Sizing Up for Safety
A line like "we will go up half a ton so you are covered" sounds like caution and is an expensive mistake. Oversized cooling short cycles, leaves humidity behind, is harder on the compressor and can make the house feel worse at the same thermostat setting.
Today Only Pricing and Same Day Signatures
Manufactured urgency, a discount that expires when the salesperson leaves, or financing paperwork pushed before the scope is written are sales tactics, not engineering. Good installers are typically booked out and will still be there next week.
No Permit and No Inspection
Permit rules for a changeout differ from town to town, so call your building department before the sales visits and learn the answer yourself. Where one is required, an installer who offers to skip it is avoiding an inspection of the gas venting, electrical and condensate work, and the unpermitted job can become your problem to disclose when you sell.
Vagueness About Startup
If nobody can tell you what gets measured on the last day, nothing will be. Charge by guesswork, unmeasured airflow and skipped combustion tests are how a properly specified system delivers mediocre comfort and an early call back.