Ontario's Plain-English Guide to Custom Home Buildingπ 705-533-1633 | βοΈ 1-866-868-6606 | βοΈ info@icfhome.ca
Furnace Replacement Cost in Ontario (2026): What a Swap Costs, Two-Stage vs Modulating, Venting, the January Premium and the Heat Pump Question
Heating, Cooling & Ventilation
Replacing a Furnace: $6,000 in September, Up to Half Again in January, and the Question You Should Ask Before Either
Most furnaces get replaced the worst possible way: on a Saturday night in January, by whoever answers the phone, at whatever price they say. A gas furnace in Ontario lasts 15 to 20 years, so you usually get some warning. This page covers what a planned swap costs, what pushes the number up, when a repair still makes sense, and the one question worth asking before you buy another furnace at all.
The numbers
$6,00095 to 98 percent gas furnace, same venting
$5,000 to $7,500plain swap, 2,000 sq ft house
20 to 50%mid-winter emergency premium
15 to 20years a gas furnace usually lasts
| Job | Range | Default or note |
|---|---|---|
| High-efficiency gas furnace, 95 to 98 percent AFUE, same venting | $4,000 to $9,000 | $6,000 |
| Straightforward swap, 2,000 sq ft house | $5,000 to $7,500 | the usual Ontario quote |
| Modulating burner and variable-speed blower | add $1,500 to $2,500 | over a basic furnace |
| Duct modification at the furnace | $300 to $1,500 | plenum and return transitions |
| Municipal permit, where needed | $90 to $350 | a like-for-like swap often needs none |
| Furnace and central AC together, existing ducts | $6,500 to $12,500 | $10,500 |
| Propane furnace | $6,000 to $8,000 | |
| Oil furnace, replacement only | $5,500 to $8,500 | |
| Emergency mid-winter replacement | 20 to 50 percent over | off-season pricing |
| Annual service, furnace or heat pump | $150 to $250 | allowance |
The heat pump lines are on the heat pump cost page and the AC lines on the central air page. HST is 13 percent on top of everything here.
Why Ontario prices are all over the map: the contractors and price guides we checked for this page quoted the same furnace swap very differently. A big-box retailer said $4,100 to $9,500. A home-services marketplace said $4,500 to $7,000 for a 95 to 98 percent furnace. A renovation quote site said $4,000 to $7,000 typical, and $9,000 and up once a fuel conversion or ductwork is involved. The gap is what is in the price: removal of the old unit, the venting, the duct transitions, the permit, the brand, and whether it is September or a January emergency. Budget $6,000 for a plain swap, and get two or three quotes on the same written scope.
Repair or replace
I set expectations the same way every time. Under about 12 years old, fix it, unless the heat exchanger is cracked. Past 15, every repair bill should be weighed against a replacement you are going to buy soon anyway. Past 20, you are driving a car with 400,000 km on it to the cottage every weekend and hoping.
A cracked heat exchanger is not a repair; that is the part that keeps combustion gases out of your air. If a gas technician finds one, the furnace gets shut off and tagged, and that is not an upsell, it is the job. Nobody but a TSSA-registered contractor with a certified gas technician opens a sealed combustion appliance, adjusts gas pressure or touches a safety control. If the house has a gas appliance, it has a CO alarm on every floor, and those alarms have an expiry date on the back.
Rule of thumb: if the furnace is past 15 years and the repair is more than about a quarter of a new one, replace it in the fall instead of paying for the repair and the emergency later.
Two-stage, modulating and the venting
A basic furnace is on or off at full fire. A two-stage one has a low fire and a high fire and spends most of the winter on low. A modulating one turns itself down in small steps to match the house, and with a variable-speed blower it runs long and quiet instead of in blasts. That adds $1,500 to $2,500. In a house that has been insulated and air sealed since the old furnace went in, it is money well spent, because the old size is now too big and a modulating burner hides some of that sin.
Venting is where the surprises live. A 95 percent furnace vents through plastic pipe out the side wall, not up the chimney. If the old furnace was a mid-efficiency 80 percent unit on the chimney, the new one needs new venting, and a gas water heater left alone on that chimney may need its vent checked as well. A tightened house with a gas appliance also needs its makeup air looked at. That is the gas technician’s call, not the salesman’s.
Before anyone sizes the replacement, ask how they sized it. The sticker on the old furnace tells you what somebody installed in 2006, not what the house needs now. The sizing mistakes page explains why a pickup truck hauling a bag of groceries never warms up.
Four houses worked through
House one: a 2,000 sq ft two-storey in Barrie, 18-year-old 95 percent furnace, replaced in September. Furnace on the same venting $6,000, new return transition $500. Subtotal $6,500, HST $845, total $7,345. No permit in this town for a like-for-like swap.
House two: the same furnace dies on January 20. At 20 to 50 percent over off-season pricing, the $6,000 furnace becomes $7,200 to $9,000 before the transition and the HST. The cheapest way to buy a furnace is to buy it before you need it.
House three: furnace and AC both 18 years old, gas-heated. Both together on the existing ducts, $10,500, $11,865 with HST. Or a cold-climate heat pump on the existing ducts at $13,000 with the new furnace at $6,000 as backup, $19,000 for dual fuel; or the heat pump plus an all-electric air handler with backup strip, $13,000 plus about $3,000 of the $2,500 to $4,000 conversion, $16,000, plus a panel upgrade at $2,500 to $4,500 if the house is on 100 A. If the house qualifies, a 3 ton cold-climate unit on a gas-heated house can get up to 3 x $500 = $1,500 back afterward from Home Renovation Savings, with pre-approval before the install. Nothing is subtracted until the cheque comes; check the program site before you sign.
House four: a propane farmhouse near Orillia. A propane furnace is $6,000 to $8,000. At $0.90 a litre, propane heat costs about 13.3 cents per delivered kWh against about 6.4 cents for a heat pump at COP 2.5 on 16 cent power. Here a heat pump wins easily, and if the house qualifies the rebate is up to $1,250 a ton. The rebate page works the example.
Where homeowners go wrong
- Signing at the kitchen table with a door-knocker. Since March 1, 2018, a supplier cannot sign a contract at your home for a furnace unless you called them first and asked them to come. A contract that breaks the rule is void. The licensing page covers the rest.
- Replacing the furnace by the old sticker. Ask for the heat loss. If nobody did one, the size is a guess.
- Buying the furnace and keeping the 18-year-old AC. They share a coil and a blower. If both are near the end, price them together, and price the heat pump at the same time.
- Not asking about the venting and the water heater. If the old furnace was on the chimney, the quote must say what happens to the chimney and whatever else is still on it.
- Skipping the yearly service. $150 to $250 a year is cheaper than a January call.
Questions people ask
How much does a new furnace cost in Ontario?
A 95 to 98 percent gas furnace on the same venting is $4,000 to $9,000 installed, about $6,000 for a typical job, and $5,000 to $7,500 for a plain swap in a 2,000 sq ft house. Add $1,500 to $2,500 for a modulating burner and variable-speed blower, and 13 percent HST.
Is it cheaper to replace a furnace in the summer?
Yes. Emergency replacements in the middle of winter run 20 to 50 percent over off-season pricing, and you get no time to compare quotes. September and October are the months to do it.
Should I replace my furnace with a heat pump?
On propane, oil or electric baseboard, almost always worth pricing; the operating cost difference is large. On natural gas it is closer, and the gas vs heat pump page does the arithmetic. If the AC is also old, dual fuel is the middle road.
Do I need a permit to replace a furnace in Ontario?
A like-for-like swap often needs no building permit, though some municipalities charge $90 to $350 where one is needed. The gas work itself is TSSA-regulated in every case and must be done by a registered contractor with a certified gas technician.
How long does a furnace last in Ontario?
Usually 15 to 20 years with yearly service. A cracked heat exchanger ends it at any age.
Price the furnace against a heat pump first
The heat pump vs gas cost calculator takes your own gas or propane price and your power bill and gives the yearly and 15-year cost both ways, so you know which machine you are shopping for before anyone comes to the house. If you already have quotes, the $99 review reads up to three of them and says which lines are missing.
Sources and further reading
- Gas furnaces: Canada energy efficiency regulations: Natural Resources Canada: the minimum AFUE rules for gas furnaces sold in Canada and what the efficiency ratings mean.
- TSSA: hire registered and certified fuels professionals: Technical Standards and Safety Authority: why gas furnace, boiler and water heater work must be done by a registered contractor with a certified technician, and how to check.
- Door-to-door sales and home service contracts: Ontario: the ban on door-to-door contracts for furnaces, air conditioners and water heaters, the 10-day cooling-off period and void contracts.
