Furnace replacement is one of the most significant mechanical decisions Ontario homeowners face. Here is everything you need to know for 2026.
When to Replace Your Furnace
Average lifespan in Ontario: 15-25 years. Replace when: age over 20, AFUE below 80%, repairs exceeding 50% of new unit cost, uneven heating, rising gas bills, yellow pilot flame.
AFUE Ratings
Ontario Building Code minimum for new residential installations: 92% AFUE. Mid-efficiency 80% units no longer permitted for new Ontario residential installations. High-efficiency condensing furnaces: 96-98% AFUE. Annual savings vs 80% unit: $300-$700/year for a typical GTA home.
Variable Speed vs Two-Stage vs Single Stage
Single stage: Full output or off. Least expensive. Two-stage: Low and high fire. Better comfort and efficiency. Variable speed: Modulates to demand — quietest, most efficient, best dehumidification. Cost premium: $500-$1,500.
Installation Costs in Ontario 2026
80,000 BTU high-efficiency furnace installed: $3,500-$6,000. Includes permits, gas line connection, new PVC venting, electrical hookup. Ductwork modifications add $500-$1,500.
Licensing
Gas furnace installation requires a licensed G2 or G1 gas technician plus mechanical permit. ESA permit required for electrical connections. Verify all contractor licences.
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