Your home’s heating and cooling system is the most complex mechanical system you own — and the one most homeowners understand least. HVAC contractors know this. The information gap between a trained technician and the average homeowner is wider in this trade than almost any other, which means consumers are more vulnerable to upsells, unnecessary replacements, and shoddy installations than in virtually any other category.

A furnace that’s installed incorrectly doesn’t just underperform — it can leak carbon monoxide. An air conditioner that’s improperly charged doesn’t just run inefficiently — it fails prematurely. A heat pump sized incorrectly for your home provides neither adequate heating nor cooling. These are not hypotheticals. They are the most common outcomes of a bad HVAC hire.

The questions in this guide are organized by stage. They apply whether you’re replacing a furnace, installing central air, upgrading to a heat pump, or just getting your system serviced before winter.

“The HVAC industry has a transparency problem. Too many homeowners are told they need a full system replacement when a repair would do, or sold a unit that’s too large for their home because it has a better margin. An informed client asking the right questions changes that dynamic completely. These are not hard questions — they just require knowing what to ask.”

— Erion from G.T.A Mechanical, HVAC specialist with over 20 years of experience providing heating, ventilation, air conditioning, and refrigeration services across Toronto, focused on energy-efficient solutions, reliable system performance, and quality workmanship

Before You Call Anyone

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Is this a repair or a replacement?

Before inviting contractors to quote, assess what you’re actually dealing with. A furnace that’s 8 years old and not heating properly may need a repair. A furnace that’s 22 years old with a cracked heat exchanger is a replacement. The decision isn’t always obvious — but having a sense of the age, maintenance history, and symptoms of your system helps you have a smarter conversation.

For more: Repair vs Replace: How Do I Know If My HVAC System Needs to Be Replaced?

Is this an emergency?

No heat in a Canadian winter is a genuine emergency. If your furnace has stopped working and temperatures are dropping, call a licensed HVAC contractor immediately. If you smell gas, leave the house, call your gas utility’s emergency line, and don’t re-enter until the utility has cleared it.

Carbon monoxide is odorless — if your CO detector activates, leave immediately and call 911.

Questions to Ask Before Hiring

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Are you licensed as an HVAC contractor and gas fitter in this region?

In many regions, anyone working on natural gas equipment — furnaces, boilers, gas lines — must hold a G2 (gas technician class 2, for residential) or G1 (class 1, for all gas work) licence issued by the relevant gas-fitting safety authority. Refrigerant handling for air conditioning and heat pump work requires certification under the federal refrigerant handling regulations.

Ask for both licences and verify them. The gas technician licence is searchable at tssa.Org.

What a good answer looks like: A specific gas technician licence number (G1 or G2) for gas work, and confirmation of refrigerant handling certification for AC/heat pump work.

Do you carry liability insurance and workers’ compensation coverage?

HVAC work involves gas lines, high-voltage electrical connections, and roof or attic work for certain equipment. A worker injured on your property without workers’ compensation coverage may leave you liable. Liability insurance covers damage to your home if something goes wrong during installation.

Ask for a certificate of insurance and a workers’ compensation coverage Clearance Certificate and verify both.

For a full breakdown: Questions to Ask an HVAC Contractor About Licensing and Insurance

Are you factory-authorized to install and service this equipment brand?

Many HVAC manufacturers require installation by factory-authorized dealers to qualify for full warranty coverage — including parts and labor warranties of 5–12 years. Ask whether the contractor is authorized for the brand they’re recommending and what warranty coverage that authorization unlocks.

What a good answer looks like: Confirmed factory authorization for the recommended brand, with documentation of what the enhanced warranty covers.

Questions About the Quote

Is the equipment being sized for my home, or are you using the existing unit’s size?

Equipment sizing is one of the most critical — and most commonly skipped — steps in HVAC installation. An oversized furnace short-cycles, wearing out components prematurely and creating temperature swings. An oversized air conditioner cools too fast without dehumidifying, leaving the home clammy. An undersized heat pump can’t maintain comfort on the coldest days.

Proper sizing requires a Manual J load calculation — a detailed assessment of your home’s heat loss and gain based on insulation levels, window area, orientation, and local climate data. Ask every contractor whether they’ll perform a Manual J calculation, or whether they’re simply replacing the existing unit with the same size.

What a good answer looks like: A Manual J load calculation included in the quote process, with the results used to specify equipment size.

What specific equipment are you recommending, and why?

Ask for the brand, model, and efficiency rating of every piece of equipment being proposed. For furnaces, the key metric is AFUE (Annual Fuel Utilization Efficiency) — 80% AFUE is standard, 96–98% is high-efficiency. For air conditioners, SEER2 (Seasonal Energy Efficiency Ratio) measures cooling efficiency. For heat pumps, both SEER2 and HSPF2 (Heating Seasonal Performance Factor) matter.

Ask why the recommended efficiency level is appropriate for your home and climate, and what the payback period is compared to a lower-efficiency option.

For more: Questions to Ask an HVAC Contractor About Equipment

What is and isn’t included in this quote?

Ask specifically whether the quote includes: removal and disposal of old equipment, all required permits, refrigerant, any ductwork modifications, thermostat replacement, and startup commissioning. Each of these can be a surprise addition to the final bill if not addressed upfront.

What a good answer looks like: A written scope of work that explicitly lists inclusions and exclusions.

For more: Questions to Ask When Getting an HVAC Quote

Questions About Installation Quality

Will you perform a combustion analysis on the new furnace after installation?

A combustion analysis verifies that a newly installed furnace is burning fuel efficiently and safely — confirming proper air-fuel ratio and identifying any combustion products that shouldn’t be present. Ask whether this is part of the standard installation process.

Will you test for carbon monoxide after installation?

Any work on a gas appliance should include a carbon monoxide test before the job is considered complete. This is a basic safety step that responsible contractors perform as standard.

Will the ductwork be inspected and sealed?

In most homes, duct leakage accounts for 20–30% of heating and cooling loss. A new high-efficiency furnace connected to leaky ducts will underperform significantly. Ask whether duct condition and sealing is part of the installation scope.

Questions About Warranties

What manufacturer warranty comes with the equipment?

Most major HVAC brands offer 10-year parts warranties on residential equipment when installed by authorized dealers and registered within the required period. Some offer 10-year labor warranties as well. Ask specifically what the warranty covers, for how long, and what registration is required.

What workmanship warranty do you offer?

Separate from the equipment warranty, the contractor should offer a written warranty on their installation. One to two years minimum is standard. Get it in writing.

For a full breakdown: Questions to Ask an HVAC Contractor About Warranties

Red Flags to Watch For

No Manual J calculation. Any contractor who sizes equipment by replacing “like for like” without a load calculation may be setting you up for an oversized system and premature failure.

No gas technician licence number for gas work. Unlicensed gas work is illegal and dangerous. This is non-negotiable.

Recommending replacement when the system is less than 10 years old. A furnace or AC unit under 10 years old can almost always be repaired. A contractor who immediately recommends replacement on a relatively young system without a thorough diagnostic is worth a second opinion.

Offering to skip the permit. HVAC installation requires permits and inspections in most jurisdictions. A contractor who suggests skipping this step is transferring legal and insurance risk to you.

Pressure to decide immediately. No HVAC job requires a same-day signature except in a genuine emergency. Take the time to get multiple quotes.

For a full guide: Red Flags When Hiring an HVAC Contractor

Before They Start: A Quick Checklist

  • Gas technician licence number verified (for gas work)
  • Refrigerant handling certification confirmed (for AC/heat pump)
  • Certificate of insurance and workers’ compensation coverage clearance received and verified
  • Manual J load calculation performed
  • Written quote with specific equipment model, efficiency rating, inclusions, and exclusions
  • Permit responsibility confirmed
  • Warranty terms — manufacturer and workmanship — in writing
  • Carbon monoxide test and commissioning confirmed as part of installation

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