It's the objection we hear more than any other: "Don't heat pumps stop working when it gets cold?" It's a fair question — and the answer, for modern equipment in a BC winter, is a confident no. Today's cold-climate heat pumps heat efficiently far below freezing. Here's the science, the real numbers for our region, and why the old reputation no longer holds.
The short answer
Yes — and comfortably so in BC
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Where the myth came from
The "heat pumps don't work in the cold" idea isn't made up — it's just out of date. Heat pumps from the 1980s and 90s were single-speed units that lost most of their capacity as temperatures approached freezing, forcing noisy, expensive backup heaters to take over. People remember that, and the reputation stuck.
Modern units are a different machine. Inverter-driven variable-speed compressors, improved refrigerants, and smarter controls let today's cold-climate models hold their output far deeper into the cold. The technology moved on; the myth didn't.
How they pull heat from cold air
This is the part that surprises people: even "cold" air contains a lot of heat energy. Air doesn't run out of usable heat until about -273°C (absolute zero), so at -5°C there's still plenty for a heat pump to gather. The refrigerant inside the system boils at an extremely low temperature, so it absorbs heat from frigid outdoor air, gets compressed (which concentrates that heat), and releases it indoors. The colder it gets, the harder the system works — but it keeps working well past anything BC throws at it.
The numbers for a BC winter
Putting Surrey's climate next to what cold-climate units can do makes the point clearly:
| Temperature | Cold-climate heat pump | How often in Surrey? |
|---|---|---|
| +5°C to 0°C | Peak efficiency | Most of winter |
| 0°C to -10°C | Full / near-full output | Cold snaps |
| -10°C to -15°C | Strong output, still efficient | Rare |
| -15°C to -25°C | Still heating, reduced capacity | Almost never |
In other words, the range where a cold-climate heat pump even begins to taper is colder than the Lower Mainland realistically gets. For brand-specific cold-weather ratings, see our best heat pumps for BC guide.
Defrost mode, explained
In damp, near-freezing weather — exactly our climate — a thin layer of frost can build on the outdoor coil. The system automatically runs a short defrost cycle: it briefly reverses to warm the coil, melts the frost, and returns to heating, usually within a few minutes. You may notice a wisp of steam from the outdoor unit. That's normal and expected — a sign the unit is managing our wet winters correctly, not a malfunction.
Do you actually need backup heat?
In colder provinces, a backup heat source is standard. In Surrey, it's usually optional. A properly sized cold-climate unit can serve as your sole heating system here. Some homeowners still choose to keep:
- A small electric backup element for total peace of mind on the rare deep-cold night.
- Their existing furnace in a hybrid (dual-fuel) setup — see our heat pump vs furnace guide.
It's a comfort and budget decision, not a technical requirement for our climate.
Why correct sizing is everything
An undersized unit is the real cause of cold-weather complaints
Get the sizing and install right, choose a genuine cold-climate model, and your heat pump will keep your home warm and your bills low through every Lower Mainland winter — no asterisks.
Worried about winter performance?
We'll size a cold-climate system properly for your home and show you exactly how it performs on Surrey's coldest days. Free assessment, honest answers.
