Do heat pumps work in Ontario winters?
Trust Build Heating & Cooling · · 5 min read
Yes. A cold-climate heat pump can heat a home through an Ontario winter. How well it does depends on three things: the model, how the system is sized for your house, and how well your house holds heat. This guide explains what happens as the temperature drops and what to check before you decide.
What "cold-climate" means
A heat pump does not make heat by burning fuel. It moves heat from the outside air into your home, and even cold air contains heat that can be moved. Cold-climate models are built to keep doing this at low temperatures, usually with a variable-speed compressor that adjusts its output to the weather.
Earlier Ontario programs gave a practical definition: the unit had to keep at least 70% of its heating capacity at -15°C and use a variable-speed compressor. The federal rebate works differently. It applies only to heat pumps on the government's Eligible Products List, and each model on the list is identified by an AHRI number. See cold climate heat pumps for how to read that.
What happens as it gets colder
Every heat pump produces less heat and works less efficiently as the outdoor temperature falls. That is normal. A well-chosen cold-climate model is designed so that the drop is gradual and the unit keeps heating at the coldest temperatures you are likely to see.
This is why one number is not enough. A brochure rating taken at a mild temperature tells you little about a January cold snap. Ask for the model's published heating capacity at -15°C, and make sure the system is sized for your home's heat loss on the coldest days, not the average day.
Do you need backup heat?
Sometimes. Some homes pair the heat pump with backup heat for the coldest nights, such as electric resistance heat or an existing furnace. Whether you need it depends on your home's heat loss and the size of the heat pump. A heat loss calculation answers the question for your house; a general rule does not.
If you plan to keep a gas furnace as the backup, note that the federal rebate page does not say whether that setup qualifies. Confirm the rules before you plan around it. See how the federal rebate works.
What makes a home a good candidate
- Insulation and air sealing: a tighter home needs a smaller system and keeps heat longer.
- Ductwork: existing ducts must be in good condition and able to carry the airflow a heat pump needs. If there are no ducts, a ductless mini-split is an option.
- Electrical panel: the new equipment needs capacity on the panel.
- Current heating: what you heat with today largely decides how your running costs will change.
How running costs compare
Compared with electric baseboards, oil or propane, a heat pump often costs less to run. Compared with natural gas, it depends. The Government of Canada warns that switching away from natural gas may not lower your heating bills, depending on your region and system. Your gas and electricity rates and your home's efficiency decide the result, so run the numbers for your own house before you commit.
Everyday tips for winter
- Keep the outdoor unit clear of snow, ice and drifting leaves, and keep air flowing around it.
- Expect occasional defrost cycles. The unit may release steam for a few minutes, which is normal.
- Check the filter on the indoor unit regularly.
- Avoid large thermostat setbacks unless your installer says they suit your system.
If you live in Vaughan or elsewhere in the GTA and want to know whether your home suits a heat pump, a written quote shows the equipment and the full project cost. You can request a free quote.