Do Heat Pumps Work in Cold Weather?

It's the most common question we hear from Muskoka homeowners: do heat pumps actually work when it's −20°C outside? The short answer is yes. Modern cold-climate heat pumps are designed for Canadian winters. The longer answer involves understanding how heat pumps work, what changes as it gets colder, and how to design a system for Muskoka.

How Can a Heat Pump Heat When It's Cold Outside?

A heat pump doesn't create heat by burning fuel. It moves heat from outside to inside. Even at −20°C, outdoor air still contains heat energy. The heat pump's refrigerant is colder than the outside air, so it absorbs that heat, and the compressor raises its temperature before releasing it inside. It works the same way a fridge moves heat out of the food compartment.

How Cold Weather Affects Heat Pumps

As temperatures drop: - Capacity decreases. There's less heat in the air to move. - Efficiency decreases, though cold-climate models stay efficient well below freezing. - Frost forms on the outdoor coil, and the heat pump runs short defrost cycles to clear it.

Standard vs Cold-Climate Heat Pumps

Older standard heat pumps lost much of their capacity below about −5°C to −10°C, which is where their bad reputation came from. Cold-climate heat pumps use variable-speed inverter compressors and enhanced refrigerant technology to maintain strong heating output at −15°C and keep operating to −25°C or lower. See Cold-Climate Heat Pumps.

Are Heat Pumps Good for Cold Climates Like Muskoka?

Yes, with the right equipment and design: 1. Choose a cold-climate model with verified low-temperature performance 2. Size it correctly from a heat loss calculation 3. Mount the outdoor unit above the snow line on a bracket or stand 4. Plan drainage so defrost water doesn't refreeze under the unit 5. Include backup heat for the coldest nights: electric heat strips or a furnace

Do You Still Need Backup Heat?

In Muskoka, most systems include backup heat for extreme cold, power interruptions, or defrost comfort. Many homeowners keep their existing gas or propane furnace in a dual-fuel system. See Heat Pump Backup Heat and Add a Heat Pump to Your Furnace.

What About Defrost Mode?

In winter, you may see steam rising from the outdoor unit and hear a whoosh as the heat pump briefly reverses to melt frost. This defrost cycle is normal and usually lasts a few minutes. See Heat Pump Defrost Mode Explained.

Real-World Experience With Heat Pumps in Really Cold Weather

Across the homes and cottages we've equipped in Gravenhurst, Bracebridge, and Muskoka Lakes, well-designed cold-climate systems carry the heating load through most of the winter. The furnace or electric backup handles only the coldest stretches. Most customers heating with propane or oil see big drops in fuel use.

Do Heat Pumps Work in Northern Ontario?

Yes. Cold-climate heat pumps are widely installed across northern Ontario and Quebec. The key is design: equipment choice, sizing, installation, and backup heat all need to match the local climate.

Tips for Getting the Best Winter Performance

• Keep snow and ice clear of the outdoor unit
• Keep filters clean
• Use steady thermostat settings instead of deep night setbacks (heat pumps work best maintaining temperature)
• Book annual heat pump maintenance

Get a Heat Pump Designed for Muskoka Winters

Bridlewood Mechanical has installed heating systems in Muskoka since 1975, and heat pumps are a core part of our work.

Book Your Free Quote

Call (705) 706-7622 or request a free quote online. Our team will get back to you quickly to book a visit.