Heating systems and controls: how each one performs

How it works: efficiency in plain numbers

Fuel-burning equipment is rated by AFUE (annual fuel utilization efficiency): the share of the fuel's energy that becomes heat in your home over a whole season. Heat pump efficiency is expressed as COP (coefficient of performance): a COP of 3 means 3 kWh of heat for every 1 kWh of electricity.

Furnaces and boilers

• Gas furnaces from around 1970 ran at about 60% AFUE, mid-1980s models at 78–84%, and condensing furnaces 90–98% (NRCan ↗). Gas and propane furnaces made since July 3, 2019 must reach at least 95% (regulations ↗).
• NRCan estimates that replacing a 78% furnace with a 95% model cuts annual energy costs by about 18%.
• New hot-water gas boilers (made since July 1, 2023) must reach 90% AFUE (NRCan ↗). A condensing boiler only reaches its rating when water returns at 45–50°C or cooler; otherwise it performs like an 82–89% non-condensing boiler.
• New oil furnaces must reach 83% AFUE and new hot-water oil boilers 86% (NRCan ↗). Oil equipment needs yearly cleaning and tuning; gas and propane equipment, servicing at least every two years (NRCan ↗).

Electric heat and heat pumps

• Electric baseboards and electric furnaces turn all of their electricity into heat. Baseboards, used in most electrically heated Canadian homes, usually cost least to install but often have very high operating costs (NRCan ↗).
• Air-source heat pumps deliver a COP of 2.0–5.4 at 8°C, falling to 1.1–3.7 at −8°C. Newer models stop between −15°C and −25°C, so backup heat is needed (NRCan ↗).
• Ground-source (geothermal) heat pumps use steadier ground temperatures for a COP of about 3 in the coldest months and cut heating costs by about 65% compared with an electric furnace.
• A dual-fuel (biénergie) system pairs a heat pump with a furnace or boiler. Below a set outdoor temperature the furnace takes over; the two don't run at the same time. Hydro-Québec's dual-energy Rate DT requires automatic switching at −12°C or −15°C, depending on the region (Hydro-Québec ↗).

Wood, pellets and outdoor wood boilers

Wood or pellets are the main heat source in about 2% of Canadian homes (Statistics Canada ↗). Efficiency and smoke depend on the appliance.

• Look for certification. Appliances certified clean-burning by the US EPA (or to the similar CSA B415.1 standard) cut smoke by as much as 90%, and advanced stoves average about one-third more efficient than conventional ones (CMHC ↗). In British Columbia, retailers may only sell CSA- or EPA-certified appliances.
• Compare overall efficiency. Ads often quote combustion efficiency; overall efficiency, the heat that reaches your rooms, may be 10% to 20% lower. The EPA's certified list has shown overall efficiency for every model since May 16, 2020 (US EPA ↗).
• Burn dry wood. Aim for 20% moisture or less: split the wood, stack it off the ground, cover the top, and season softwood at least 6 months and hardwood 12.
• Inspect every year. NRCan advises yearly stove and chimney inspections. WETT (Wood Energy Technology Transfer) says its basic (Level 1) inspection by a WETT-certified professional is used for most insurance and real estate needs (WETT ↗).

Outdoor wood boilers sit up to 40 m from the house and pipe hot water to it. Older designs produced large smoke plumes at efficiencies as low as 40%, and many municipalities restrict where they can go (CMHC). In BC, new outdoor wood boilers must be at least 40 m from adjacent property lines (10 m for pellet boilers) (B.C. ↗). In Ontario, rules are local: North Dundas requires a certified unit, a permit, 30 m from any property line and 100 m from a neighbour's house, and bans them in subdivisions and residential zones (by-law ↗). Check with your municipality first.

Heating systems compared

Minimums are from current NRCan regulations. Other ranges come from NRCan and CMHC guides; the figures for wood, pellets and older gas equipment date from NRCan's 2012 Heating with Gas guide.

Controls and free heat from the sun

• Programmable or smart thermostats. Lowering the temperature 1°C for eight hours saves about 2% of heating energy. Don't go below 17°C, which risks moisture in exterior walls (NRCan ↗); ENERGY STAR Canada suggests 17°C asleep or away and 20°C at home (ENERGY STAR ↗).
• Heat pumps. Keep setbacks to 2°C or less (or use a smart thermostat that recovers early), and set electric backup 2–3°C below the heat pump setting (NRCan).
• Electric baseboards. Electronic thermostats that hold within 0.5°C of the setting could save about 3% (NRCan).
• Zones. Radiator valves or duct dampers with their own thermostats let you heat rooms differently.

Passive solar gain is free heat through your windows. A window's solar heat gain coefficient (SHGC, from 0 to 1) shows how much of the sun's heat it lets in. NRCan suggests above 0.4 for pre-1980 or poorly sealed homes, passive solar designs and sunny areas with short cooling seasons, and 0.3–0.4 for new or substantially renovated homes. Curtains and blinds cut heat loss through glass in winter and block summer sun (NRCan ↗).

When to repair, replace or switch

Hydro One says a furnace can work reliably for 15 to 20 years, likely longer if maintained. Warning signs: frequent repairs, rising bills at the same setting, popping, banging or screeching, and dust or soot around registers. It suggests replacing a furnace over 15 years old when repairs would cost 50% or more of a new high-efficiency unit (Hydro One ↗).

Call a technician promptly about signs of combustion trouble: soot or staining around a burner, damper or vent connection, melted plastic fittings on top of a tank water heater, unusual odours, frequent headaches or nausea, or carbon monoxide alarms. Building codes now require a CO alarm in every home with a fuel-burning appliance or attached garage (NRCan). See combustion safety testing.

Air-source heat pumps last 15–20 years and ground-source units 20–25. When a central air conditioner needs replacing, NRCan notes a heat pump often costs little more; see thinking about a heat pump. After insulation and air sealing, a furnace may be oversized and short-cycle; staged and modulating furnaces fire at 60–100% of capacity for steadier cycles (NRCan).

What an energy advisor checks

In an EnerGuide evaluation, the advisor records the size and efficiency ratings of your heating, cooling and water heating equipment, photographs mechanical systems and any wood-burning appliances, and measures airtightness with a blower door test. Fuel-fired heating is turned down during the test because the fan can affect safe operation of gas appliances (NRCan ↗).

NRCan advises sealing air leaks and insulating before choosing a heat pump, because a tighter house can use a smaller unit. Equipment should be sized with a recognized load calculation such as CSA F280 (see heat loss calculation), and an all-electric air-source or ground-source heat pump normally needs a 200-amp electrical service.

Mistakes to avoid and next steps

• Replacing like for like without a load calculation: oversized equipment short-cycles or runs inefficiently, and an undersized heat pump leans on backup heat.
• Counting on an open fireplace for heat: NRCan says most can't provide any net heat gain.
• Deep setbacks with a heat pump, which bring on backup heat.
• Letting a door-to-door “inspector” in: NRCan and its programs never perform or authorize unsolicited inspections (NRCan ↗).

Next steps: check rebates where you live on our programs page, compare running costs with the energy cost calculator, and put upgrades in order with the planner.