Replace a furnace, AC, or heat pump
Heating and cooling replacement is the most common four-figure home decision in Ontario, and the one most often sold under time pressure — usually in January, usually when the old unit has just failed. Gas work is strictly regulated: it must be done by a TSSA-certified technician working for a registered contractor. There is no homeowner self-work path here, unlike electrical. The single biggest quality variable is not the brand on the box, it is whether anyone calculated what size your house actually needs.
What applies when you replace a furnace, AC, or heat pump in Ontario?
In Ontario, this job can involve three bodies: the Technical Standards and Safety Authority (TSSA) — certified gas technician from a registered contractor; the Electrical Safety Authority (ESA) — notification for associated electrical work; and your municipal building department — permit may apply depending on scope and municipality.
Source: TSSA — fuels industry professionals (Technical Standards and Safety Act, 2000) · Reviewed 2026-09-10 (reviewer placeholder — not credentialed sign-off)
What applies
Certified gas technician from a registered contractor
Who files The contractor holds the registration; the technician holds the certification.
Applies to the appliance, the gas line, and the venting. Not optional and not delegable to a general handyman.
Notification for associated electrical work
Who files The licensed electrical contractor.
Comes up on heat pump and AC installs that need a new circuit or a disconnect.
Permit may apply depending on scope and municipality
Who files The contractor, where required.
Straight like-for-like swaps often do not need a building permit, but venting changes and fuel conversions can. Confirm locally.
Who has to be certified
| Trade | What they need | Ask them |
|---|---|---|
| Gas | TSSA gas technician certification (G1, G2, or G3) and a registered contractor TSSA — fuels safety |
“Can I see the technician's TSSA certificate and your contractor registration?” |
| Electrical | ECRA/ESA licensed electrical contractor for any new circuit Find a licensed electrical contractor (ESA) |
“Who is doing the electrical, and what is their ESA licence number?” |
What a complete quote contains
- A heat loss and heat gain calculation for your house — not a size copied from the old unit
- The specific model number and its efficiency rating, not just a tier name like "mid-range"
- Whether the existing venting is being reused, modified, or replaced
- Whether existing ductwork is adequate for the new equipment's airflow
- Permit and inspection responsibility
- Manufacturer warranty terms and what registration is required to activate them
- Labour warranty, stated separately from the manufacturer warranty
- Removal and disposal of the old equipment
- Any available rebate the equipment qualifies for, and who files it
Questions to ask out loud
Did you do a heat loss calculation, and can I see it?
Good answer Produces an actual calculation based on your house's size, insulation, and windows.
Worrying answer Sized it from the old unit, or from square footage alone. Oversizing is the most common defect in Ontario residential HVAC and it causes short cycling, humidity problems, and premature failure.
What is the technician's TSSA certification?
Good answer Names the certification level and the registered contractor.
Worrying answer Deflects, or says certification isn't needed for a straight swap.
Is the existing venting being reused?
Good answer Explains what was inspected and why it is or isn't adequate for the new appliance.
Worrying answer Doesn't mention venting at all.
What is the labour warranty, separate from the manufacturer's?
Good answer A stated number of years for their own workmanship.
Worrying answer Points only at the manufacturer warranty.
What happens if this fails on the coldest night of the year?
Good answer A stated response commitment.
Worrying answer Vague reassurance.
Watch for
high Unsolicited visit or call about your furnace, especially offering an inspection.
But before you accuse anyone Ontario restricted unsolicited door-to-door sales of home comfort equipment after sustained abuse in exactly this category. If they came to you unprompted, be sceptical.
high Price only valid today.
But before you accuse anyone None that survives scrutiny on a five-figure decision. If you signed in your home, you have a 10 calendar-day cooling-off period.
high A rental or lease agreement presented as though it were a purchase.
But before you accuse anyone Rentals can be legitimate, but they can attach to your title and complicate a future sale. Read what you are signing, and know it is a rental.
medium Quote with no model number.
But before you accuse anyone Sometimes an early ballpark. Insist on the model number before you sign.
medium No mention of a heat loss calculation.
But before you accuse anyone Very common practice, which does not make it right. Ask for it.
Currency note
This category is heavily rebate-driven, and rebate programs change on their own schedule, independent of building law. Confirm any rebate directly with the program before you let it affect your decision — do not take the contractor's word for what is currently available.
Systems this job touches
Sources and review
Reviewed Reviewed 2026-09-10 Next review 2027-03-09 Tier A · 180-day SLA Reviewer: Trade reviewer (to be appointed) (placeholder)