Replacing a furnace is one of the bigger purchases you’ll make for your home. Prices vary a lot from home to home, and a quote over the phone is rarely accurate. Here’s what actually drives the cost, so you can compare quotes with confidence.
Typical furnace replacement costs in Ontario (2026)
Most Ontario homeowners pay about $3,500–$9,000 to replace a gas furnace, depending mainly on the furnace’s staging and how much the installation involves. Here’s how public Canadian cost guides break it down:
| Furnace or add-on | Typical installed range in Ontario |
|---|---|
| Standard single-stage high-efficiency gas furnace | About $3,500–$5,500 |
| Two-stage high-efficiency gas furnace | About $4,500–$7,500 |
| Modulating furnace with variable-speed blower | About $6,000–$9,000 |
| Furnace and central air conditioner replaced together | About $8,000–$14,000 |
| Ductwork changes at the furnace (plenum, transitions) | About $300–$1,500 extra |
| Whole-home humidifier | About $500–$1,500 extra |
These are typical installed price ranges in Ontario based on public sources (listed below), including equipment and standard installation, before tax and rebates. They’re not a Lancaster quote; your price depends on your home and the system you choose.
The factors below explain where your home is likely to land in those ranges. To compare brands, see Trane vs. Carrier furnaces and the best furnace brands in Canada, or browse the furnaces we carry.
1. The right size for your home
A furnace should be sized with a proper heat-loss calculation (in Canada, the CSA F280 standard), not by matching the old furnace or the home’s square footage. Insulation, windows, air leakage and layout all matter. An oversized furnace costs more to buy, short-cycles and wastes energy; an undersized one can’t keep up on the coldest days.
2. Efficiency (AFUE)
AFUE measures how much of the gas becomes heat in your home. New gas furnaces sold in Canada are high-efficiency condensing models, and top models reach about 97–98% AFUE. Higher efficiency costs more up front but lowers your gas bills for the life of the furnace.
3. Staging: single-stage, two-stage or modulating
- Single-stage: on at full output or off. The simplest and lowest cost.
- Two-stage: runs on a low setting most of the time and switches to high on cold days. Quieter, with more even temperatures.
- Modulating: adjusts output in small steps to match the heat your home needs. The most comfortable, quietest and efficient option.
4. Blower motor
Variable-speed (ECM) blowers use less electricity, run quietly, improve air filtration and help your air conditioner remove humidity in summer.
5. Installation conditions
- Venting: converting from an old chimney-vented furnace to PVC venting, or rerouting vent pipes.
- Gas line: changes to the gas supply or a new shut-off valve.
- Ductwork: modifying the plenum or fixing undersized or leaky ducts. See ductwork repair.
- Condensate drain: adding a floor drain connection or condensate pump.
- Access: tight crawlspaces, finished basements and attic installations take longer.
6. Matching your air conditioner or heat pump
If your air conditioner is old or uses R-22 refrigerant, replacing both at the same time is often more cost-effective and ensures the indoor coil and outdoor unit are properly matched. A heat pump paired with a furnace (a hybrid system) is also worth considering, and it qualifies for more rebates.
7. Add-ons
Smart thermostats, whole-home humidifiers, upgraded filtration, UV air purifiers and extended warranties all add to the cost, and to your comfort.
8. Rebates, financing and warranty
- Rebates: check our rebates guide for current federal and Ontario programs.
- Financing: spread the cost over monthly payments with Financeit financing.
- Warranty: manufacturer parts warranties usually require registration and annual maintenance. Our service plans make that easy.
How to compare furnace quotes
Ask every contractor:
- Did you do a heat-loss calculation, or are you matching the old furnace’s size?
- What’s the exact model number, AFUE and staging?
- What’s included: venting, gas line, ductwork changes, condensate, thermostat, removal and disposal, permit?
- What warranty is included on parts and on labour?
Get an accurate price
Lancaster Heating and Cooling has been installing furnaces in Hamilton since 1955. We’ll assess your home, explain your options from Trane, Carrier, Goodman and the other brands we carry, and give you a clear, itemized quote. Request a free quote or call 905-388-3333.
Sources
Typical ranges are rounded from these public Canadian sources (checked November 2026):
- HomeStars: furnace replacement cost and HVAC installation cost
- The Home Depot Canada: cost to install a gas furnace
- Reno Quotes: furnace replacement cost in Canada (2026)
- FurnacePrices.ca: complete furnace buying guide
- The Heating Guide: furnace replacement cost in Ontario
- Green Building Canada: heat pumps vs. gas furnaces vs. hybrid systems
- Carrier Canada: whole-house humidifier costs
