Gas Furnace: Repair or Replace? (2026 cost comparison)
The rule of thumb, from Consumer Reports: don't spend more than 50% of a comparable new unit on fixing the old one. For a gas furnace, that 50% line is about $1,250–$2,750 CAD — a new unit runs $2,500–$5,500 CAD and typically lasts 15–20 years. If a repair quote lands under that line and the gas furnace is not yet past its expected life, repair usually wins. Reviewed July 2026.
Repair vs. replace, side by side Estimated
| Cost | Estimated range |
|---|---|
| Typical repair (this gas furnace, all faults we price) | $75–$3,500 CAD |
| New gas furnace (unit only) | $2,500–$5,500 CAD |
| The 50% line half a comparable new unit | $1,250–$2,750 CAD |
Repair: min–max of every gas furnace fault we price (sources on each linked problem page) · New unit: Hydro One · Lifespan 15–20 years: Hydro One, Carrier Canada, Enercare, Canada HVAC, The HVAC Service Solutions · 50% rule: Hydro One · Reviewed July 2026 · Estimated
Age × repair-cost worksheet Estimated
Find your gas furnace's age down the side and your repair quote across the top. The cell is the way the 50% rule points — Estimated guidance, not advice.
| Age of unit | Repair < 30% of a new gas furnaceunder $750–$1,650 CAD | Repair 30–50%$750–$1,650 CAD – $1,250–$2,750 CAD | Repair > 50%over $1,250–$2,750 CAD |
|---|---|---|---|
| Under 9 years first half of typical life | Repair likely | Repair likely | Compare quotes |
| 9–20 years second half, under typical lifespan | Repair likely | Compare quotes | Replace likely |
| Over 20 years at or beyond typical lifespan | Compare quotes | Replace likely | Replace likely |
How this is built: we apply the 50% rule (Hydro One) — spend no more than half a comparable new unit's cost on a repair — with its lifespan corollary (replacement is favored once the unit is past the midpoint of its expected life and the quote tops 50%). Columns are your repair quote as a share of a new gas furnace ($2,500–$5,500 CAD); the $1,250–$2,750 CAD and $750–$1,650 CAD thresholds are just 50% and 30% of that range. Rows use the midpoint of the expected life (about 9 years — halfway through a typical 18-year lifespan) and the top of the sourced 15–20 years range (20 years). Nothing here is a per-unit price or a recommendation — it is a transparent reading of the rule.
The strongest-agreement lifespan in this file: five independent Canadian sources — a provincial utility, the manufacturer's Canadian arm, a national service company and two contractors — all state 15-20 years, with Canadian pages attributing the band to a long, hard heating season rather than to hours of runtime. Enercare adds that inspection and maintenance can extend furnace life by five to ten years over unmaintained units, and Carrier Canada notes furnaces "can last up to 30 years" for high-quality well-maintained models — an outlier above the band, not a revision to it. Hydro One is also the one Canadian source in this file that quotes a furnace replacement price directly — a new furnace installation "between $2,500 and $5,500 or more" CAD — and that figure is carried in new_unit_cad above (total installed, not FX-converted from anything); Hydro One additionally mentions a $250 CAD Ontario rebate for a high-efficiency furnace with an ECM installed through an approved contractor. install_delivery_cad is null because Hydro One quotes a single bundled installed total, not a separable equipment/labour split. ELECTRIC FURNACES, which are not a taxonomy type: two Canadian sources (Canada HVAC, The HVAC Service Solutions) put them at 20-30 years — noted so the longer electric figure is never mistaken for the gas number.
One more thing before you replace
A newer gas furnace can cut energy and water use, which shifts the math on an older unit even when a repair is cheap: ENERGY STAR notes clothes washers over ~10 years and refrigerators over ~15 years are common efficiency-driven replacements.
Energy note: · Reviewed July 2026 · Estimated · Informational only
Price the repair first
Before you decide, get the likely repair figure for the exact fault — each page localizes to your metro:
- Full gas furnace cost guide
- Not heating / blowing cold air
- Won't turn on / no power
- Short cycling (turns on and off)
- Igniter (hot surface ignitor) replacement
- Flame sensor cleaning / replacement
- Blower motor replacement
- Gas valve replacement
- Control board replacement
- Cracked heat exchanger replacement
- Pilot light / thermocouple won't stay lit
- Noisy or loud (banging, rumbling, squealing)
Estimated ranges — see the methodology for how we build the repair figures and their named sources. This page is informational and is not repair, purchasing, or financial advice.
Reviewed by a Red Seal–certified appliance technician who also holds a Technical Safety BC gas ticket (Gas-C) and an ODS/halocarbon refrigerant ticket (CFC/HCFC/HFC).