Heat Pump Not Keeping Up This Winter? What's Normal in Ontario Cold (and What Isn't)
A heat pump doesn't make heat the way a furnace does — it pulls heat out of the outdoor air and moves it inside. On a mild day that's easy work. On a -15°C January night in Barrie or a damp -5°C evening in London, there's simply less heat out there to grab, so the system has to work harder to deliver the same comfort.
That's normal physics, not a defect. But it does mean a heat pump can feel very different from the gas furnace you might be used to, and it's worth knowing what's expected behaviour versus what's actually a problem worth a service call.
What's actually normal in an Ontario winter
The defrost cycle
Every so often, especially in damp or snowy weather, you'll notice the outdoor unit pause, or you'll feel a few minutes of cooler air indoors. That's the defrost cycle — the system is briefly melting frost off the outdoor coil so it can keep absorbing heat efficiently. It's supposed to happen, and it shouldn't last more than 10–15 minutes.
Backup heat kicking in
Many Ontario homes run a "hybrid" or dual-fuel setup — a heat pump paired with a gas furnace or electric backup coil that takes over once outdoor temperatures drop below a set point. If you hear your furnace fire up on the coldest nights, that's the system doing exactly what it was designed to do, not the heat pump failing.
Lower output on the coldest days
Standard heat pumps typically lose meaningful capacity somewhere around -15°C to -20°C, which is why backup heat matters here. Cold-climate heat pumps are built differently and can keep producing useful heat down to roughly -25°C to -30°C — a real consideration if you're shopping for a new system and want to lean on the heat pump more and the furnace less.
Signs it's actually a problem, not just winter
A service call is worth it if you notice:
- The outdoor unit is caked in thick ice that doesn't clear after a defrost cycle
- The system runs constantly but the house still feels cold, even with backup heat on
- Grinding, buzzing, or clicking noises that weren't there before
- Backup heat never engages even when it's well below freezing
- Low or no airflow from the indoor vents
Any of these point to something mechanical or electrical — low refrigerant, a failing defrost sensor, a stuck relay, a dirty outdoor coil — and that's not something to troubleshoot yourself in the middle of a cold snap.
Getting the setup right for where you live
Ontario's winter isn't the same everywhere we work. A home in downtown Toronto sees milder lows than one in rural Ottawa or the Tri-Cities, and the right balance of heat pump and backup heat shifts accordingly. Our licensed, TSSA-certified technicians size and set up heat pump systems across the GTA, Hamilton, London, Kitchener-Waterloo and Ottawa based on the actual climate your home sits in, not a one-size-fits-all chart.
If you're weighing a heat pump upgrade, it's also worth knowing that Ontario's Home Renovation Savings Program, delivered through Enbridge Gas and Save on Energy, currently offers rebates up to $7,500 for qualifying air-source heat pumps and up to $12,000 for ground-source systems. Amounts and eligibility can change, so check our current rebates page or ask us directly when you call — we'll tell you exactly what applies to your home before you commit to anything.
When to call instead of waiting it out
If your system is just running longer or the furnace is kicking in on the coldest nights, that's expected. If it's icing up, short-cycling, making noise, or simply not keeping the house warm no matter what, don't wait for it to get worse. We offer heat pump repair across Ontario, and if your current system is on its last legs, we can walk you through financing options for a replacement that's actually sized for our winters.
Not sure if what you're seeing is normal or not? That's exactly what a quick phone call is for.
Call 1-888-705-7368 for a free quote or a straight answer on what's going on with your system — we're available 24/7 across the GTA, Hamilton, London, Kitchener-Waterloo and Ottawa.
Frequently Asked Questions
Is it normal for a heat pump to blow cool air sometimes in winter?
Yes. That's usually the defrost cycle, which melts frost off the outdoor coil so the system keeps working efficiently. It typically lasts 10–15 minutes and then switches back to heating.
Do I need a backup furnace with a heat pump in Ontario?
Many homes here run a hybrid setup, with a heat pump paired with a gas furnace or electric backup coil, since a standard heat pump's output drops once temperatures fall below about -15°C to -20°C. Whether you need backup depends on the heat pump model and how cold your area typically gets.
How cold is too cold for a heat pump to work?
Standard heat pumps lose meaningful capacity around -15°C to -20°C. Cold-climate heat pumps are built to keep producing useful heat down to roughly -25°C to -30°C, which covers nearly every Ontario winter night.