If your furnace is over 15 years old or has needed two or more repairs in the past few years, you're likely facing replacement sooner than later. The question every Toronto homeowner asks first: how much will it cost?
The honest answer is that furnace replacement in Toronto in 2026 runs anywhere from $3,800 to $8,500 for most residential homes — but the range is wide because several significant variables affect the final number. This guide breaks down exactly what drives the cost and what you can expect to pay for your specific situation.
Quick Answer: Furnace Replacement Cost Summary
| Furnace Type | Installed Price Range |
|---|---|
| 80% AFUE mid-efficiency (standard) | $3,800 – $5,500 |
| 96% AFUE high-efficiency (single-stage) | $5,000 – $6,800 |
| 96% AFUE high-efficiency (two-stage) | $6,000 – $7,500 |
| 98–99% AFUE variable-speed modulating | $7,000 – $8,500+ |
All prices above include equipment, labour, gas permit, and TSSA inspection. They do not include significant ductwork modifications, electrical panel upgrades, or gas line changes — those are quoted separately if needed.
What Drives the Cost of Furnace Replacement
1. Furnace Efficiency (AFUE Rating)
The biggest cost variable is whether you choose an 80% AFUE (mid-efficiency) or 96% AFUE (high-efficiency) furnace. The difference between the two is how they vent combustion gases.
An 80% AFUE furnace uses a metal flue pipe through the chimney — the same venting your old furnace uses. This makes replacement straightforward. A 96% AFUE furnace uses PVC pipes vented directly through an exterior wall, which requires running new plastic vent pipes. This adds $300–$600 to the installation and takes longer, but the equipment itself is more efficient — it converts 96 cents of every dollar of gas into heat versus 80 cents for the standard unit.
For most Toronto homeowners staying in their home for 8+ years, the 96% unit pays for itself through lower gas bills within 4–7 years. For homeowners planning to sell in 2–3 years, the 80% unit is often the more practical choice.
2. Single-Stage vs. Two-Stage vs. Variable-Speed
Beyond efficiency, furnaces come in three operating modes. A single-stage furnace runs at 100% capacity whenever it fires — it's either fully on or fully off. This is the most affordable option. A two-stage furnace runs at roughly 65% for mild days and 100% on cold days. It runs longer cycles, distributes heat more evenly, and is quieter. A variable-speed or modulating furnace continuously adjusts output between 40% and 100% — the quietest, most comfortable, and most energy-efficient option, but also the most expensive.
For a typical 1,500–2,500 sq ft Toronto detached home, a two-stage 96% AFUE furnace hits the best balance of comfort, efficiency, and value. The variable-speed models make the most sense in larger homes or for homeowners who prioritize minimal temperature swings and the quietest possible operation.
3. Furnace Size (BTU Output)
Furnace sizing matters more than most people realize. An oversized furnace short-cycles — it reaches temperature quickly, shuts off, and repeats this cycle every few minutes. This accelerates wear on every component and leaves rooms feeling uneven. An undersized furnace runs constantly without reaching temperature on cold days.
Proper sizing requires a Manual J heat load calculation based on your home's square footage, insulation levels, window area, and ceiling heights. Most Toronto homes between 1,500–2,500 sq ft need a 60,000–100,000 BTU furnace. A properly sized replacement usually matches the existing unit within one size bracket, but we always verify before recommending anything.
4. Brand and Warranty
Equipment cost varies by brand, but the differences are narrower than most people expect at similar efficiency and feature levels. Lennox, Carrier, and Trane sit at the premium end — excellent engineering, strong dealer support, and premium warranties. Goodman and York offer strong value at lower price points without sacrificing reliability at the equivalent efficiency tier. We recommend the brand that fits your budget and timeline, not the one with the highest margin.
5. Installation Complexity
A straightforward like-for-like swap — same furnace type, same location, same venting — is the most affordable installation. Costs increase for jobs that require relocating the furnace, changing venting type (80% to 96% AFUE), upgrading the gas line, adding a condensate drain, or modifying existing ductwork. These add-ons are quoted separately and only recommended when they're genuinely needed.
Ontario Gas Permit: What You Need to Know
All gas appliance replacements in Ontario require a gas permit and TSSA inspection. This is not optional — it's provincial law. The permit must be pulled before work begins, and an inspection is required to close the permit.
A reputable contractor handles the permit application and inspection scheduling on your behalf. It should be included in your quote — not charged as a surprise line item afterward. If a contractor quotes you a price that "doesn't include permits," ask why. Skipping permits on gas work voids your homeowner's insurance and creates personal liability if something goes wrong. See our furnace replacement service page for what the full process looks like when we do the job.
Repair vs. Replace: When Does Replacement Make Sense?
The decision to repair or replace comes down to a few key factors. The industry standard rule of thumb is: if the repair cost exceeds 50% of the cost of a new furnace and the unit is over 10 years old, replacement is usually the better financial decision. If the furnace is over 15 years old, that threshold drops to any repair over $800.
Certain conditions always favour replacement regardless of cost. A cracked heat exchanger is a safety issue — it allows combustion gases including carbon monoxide to enter your living space. This is a replace-immediately situation, not a repair. Similarly, a failed gas valve on a 15-year-old furnace often makes more sense to replace than repair, since the labour to access and replace the valve on an old unit approaches the cost of new equipment.
You can learn more about common furnace problems on our furnace repair page, which covers typical repair costs and when they make financial sense.
Best Time to Replace Your Furnace in Toronto
The best months for furnace replacement in Toronto are September, October, April, and May. These shoulder seasons offer the best availability and, in some cases, slightly better pricing. HVAC companies are not at peak demand, so booking windows are shorter and technicians can spend more time on each job.
Avoid December through February if you can. Emergency demand peaks, and both pricing and lead times increase. Same-day replacement is available year-round when a furnace fails in winter, but it commands premium pricing. If your furnace is showing signs of decline (higher bills, uneven heat, unusual noises), replacing it proactively in fall is almost always cheaper than replacing it in an emergency on a January night.
What's Included in a Good Furnace Replacement Quote
A properly itemized furnace replacement quote from a reputable Toronto HVAC contractor should include: equipment cost, labour, venting (if changing from 80% to 96%), gas permit, TSSA inspection, removal and disposal of old furnace, startup and commissioning, and at minimum a one-year labour warranty. Equipment warranties from major manufacturers run 5–10 years on parts when registered.
If a quote is missing any of these items — especially the permit — ask about it directly before signing. If you're in Thornhill, York Region, or anywhere across the GTA and want a written quote you can compare, contact our Thornhill team for a same-day estimate.