HVAC is where the most expensive mistakes in home services get made, and almost none of them are about brand. The single biggest determinant of whether you are happy in five years is whether the system was sized and installed correctly. An oversized furnace short-cycles, wears out early, and leaves your house unevenly heated - and oversizing is common because it is the safe guess when nobody does the math.
The math has a name: a heat loss and heat gain calculation, often called a Manual J. A contractor who performs one and shows it to you is telling you something meaningful about how they work. A contractor who sizes your replacement by reading the label on the old unit is repeating whatever guess was made last time.
What hvac contractors do
- Furnace replacement and installation, gas and electric
- Central air conditioning
- Cold-climate heat pumps, ducted and ductless
- Ductwork design, modification and sealing
- Air handlers, HRVs and ventilation
- Annual maintenance and safety inspections
Does an HVAC contractor need a licence in Ontario?
Yes for the parts that matter. Gas work requires TSSA certification, and refrigerant work requires a 313A or 313D certificate plus environmental handling certification.
TSSA Gas Technician certificate (G1, G2 or G3)
Legally required for anyone connecting, servicing or venting gas-fired equipment. G2 covers most residential work; G3 is an entry level that must work under supervision.
Verify with: The Technical Standards and Safety Authority regulates fuel safety in Ontario.
Open the official lookupCertificate of Qualification, 313A or 313D
313A is the full Refrigeration and Air Conditioning Systems Mechanic; 313D is the residential air conditioning equivalent. Both are compulsory trades.
Verify with: Skilled Trades Ontario maintains the public register.
Open the official lookupODP / refrigerant handling certification
Required to legally purchase and handle refrigerant. Relevant to any AC or heat pump work.
Manufacturer certification for the equipment being installed
Not a legal requirement, but many manufacturer warranties are only valid when installed by a certified dealer. Ask before assuming you have a ten-year warranty.
What it costs in Ontario
Ontario and federal rebate programs for heat pumps change frequently and can move the effective cost by thousands. Ask the contractor which programs they are currently registered to submit for - registration matters, because some rebates require the installer to be enrolled.
| Job | Typical range |
|---|---|
| Annual maintenance / tune-upWorth it mainly for the safety inspection on gas equipment. | $130 – $250 |
| Service call diagnosticEmergency and after-hours rates run higher. | $100 – $200 |
| Gas furnace replacement, high-efficiencyInstalled. Venting changes and ductwork modifications push toward the top. | $4,500 – $8,500 |
| Central air conditioner replacementOften bundled with a furnace replacement at a lower combined price. | $3,800 – $7,000 |
| Cold-climate ducted heat pumpBefore rebates, which can be substantial. Confirm current program status. | $9,000 – $18,000 |
| Ductless mini-split, single zoneEach additional indoor head adds roughly $1,500 to $3,000. | $4,000 – $7,000 |
| Duct cleaningLegitimate after renovation work. Be sceptical of unsolicited offers well under this range. | $300 – $700 |
These are planning estimates for Ontario, not quotes, and they move with material prices and demand. Use them to sanity-check a quote, not to argue one down.
Questions to ask before you hire
- 1Will you perform a heat loss and heat gain calculation, and can I see it?
- 2Who on the crew holds the TSSA gas certificate, and at what level?
- 3Is the equipment warranty conditional on registration or on installer certification?
- 4What exactly is covered by your labour warranty, and for how long?
- 5Does this quote include removal and disposal of the old equipment?
- 6Which rebate programs are you registered to submit for, and do you handle the paperwork?
Warning signs
- A replacement quote produced without anyone measuring anything or looking at your ductwork.
- Sizing justified purely by matching the old unit.
- Unsolicited door-to-door or phone offers for furnace or duct inspections. Ontario has a long history of aggressive HVAC door-to-door sales, and rules restricting it exist for good reason.
- A rental contract presented as a purchase. Read whether you are buying equipment or signing a long-term rental with an exit fee.
- Pressure to sign the same day to hold a rebate or price. Legitimate rebate deadlines are published and verifiable.
How to read reviews for this trade
HVAC reviews are dominated by the install experience, which happens once, rather than by how the system performs in year four. Search the review text for mentions of callbacks and follow-up service. A contractor who returns without argument to fix a commissioning issue is worth more than one with a slightly higher average.
Some of this you can do yourself
Not every job in this trade needs a contractor. These guides cover the ones that do not, and say plainly where to stop.