Stay Warm at -20°C with the Right Heat Pump

Cold nights are a fact of life in Ottawa, so it makes sense to think about next winter even while the snow is melting. If you are planning upgrades to your heating system, a cold-climate heat pump is worth a serious look. These systems are built to keep working when the thermometer dips to -20°C and below, not just on mild days.  

In this article, we will talk about what actually happens when a heat pump runs in deep cold, how efficient it is at -20°C, what defrost cycles and backup heat really mean, and simple ways to stay comfortable. We work with homes and businesses in the Ottawa area, so we design and service systems that match our local weather, not just a lab test.

How Cold-Climate Heat Pumps Really Perform at -20°C

A cold-climate heat pump is not the same as a standard unit that is only happy around freezing. It is designed with special compressors, controls and refrigerants that let it keep pulling heat from the air even during a serious cold snap. That does not mean it works the same at -20°C as it does at 0°C, but it does mean it keeps heating when a regular unit might struggle.  

As outdoor temperature drops, two things happen in a heat pump: its heating capacity goes down and its efficiency drops. A good cold-climate unit often keeps a large share of its rated heating capacity at -20°C, so it can still carry most or all of the load in a well-insulated home. In that kind of weather, you might see a coefficient of performance, or COP, in the range that still gives more heat out than electricity in, even if it is lower than on mild days.  

There are clear differences between entry-level, mid-range and premium inverter-driven systems.  

• Entry-level models may work in cold weather but can lose capacity faster and rely on backup heat more often.  
• Mid-range systems usually balance cost and performance and stay effective in most Ottawa winter conditions.  
• Premium inverter-driven units are designed for low ambient temperatures, often down to around -25°C or colder, so they hold capacity longer and modulate more smoothly.  

When we design a system, we look at the local design temperature, the insulation level of the building and the results of a heat loss calculation. That helps us pick equipment that is sized to handle typical Ottawa winter conditions with some room for colder nights, without going so large that the system cycles on and off too often.

Understanding COP, Energy Bills and Comfort

COP stands for Coefficient of Performance. In simple terms, it is how many units of heat you get out for each unit of electricity you put in. A COP of 2 means the heat pump delivers twice as much heat energy as the electrical energy it uses. This tells you far more about real efficiency than just looking at BTUs on a label.  

COP changes as outdoor temperature changes. On a mild day around 0°C, many cold-climate units have a higher COP, so they are very efficient. At -10°C, the COP drops but is still often well above 1. By -20°C, it is lower again, but in many cases it still beats electric baseboards and can compete with or complement fuel systems like natural gas or propane, depending on local energy rates and the exact equipment.  

Homeowners often ask two big questions: will a heat pump still save money at -20°C, and will it feel as warm as a furnace?  

• A well-designed system can still offer savings across the full heating season, even if efficiency dips on the coldest nights.  
• The air it delivers is usually cooler than furnace air but runs longer and more steadily, which can feel more even and comfortable.  
• Comfort depends a lot on ductwork, airflow and how the thermostat is set up, not just on the unit itself.  

Older Ottawa homes can be drafty or have small ducts, so we pay close attention to room-by-room loads, airflow, zoning, and thermostat strategy. With the right design, a heat pump can keep temperatures even from level to level and reduce cold spots that you might be used to with traditional systems.

Defrost Cycles and Backup Heat on the Coldest Days

On humid, sub-zero days, frost builds up on the outdoor coil because the unit is pulling heat out of cold, moist air. That frost acts like a blanket and reduces performance, so the system runs an automatic defrost cycle. It briefly switches mode to warm the outdoor coil, melts the ice, and then goes back to heating the home.  

During defrost, homeowners often notice:  

• A temporary plume of steam rising from the outdoor unit.  
• The outdoor fan slowing down or stopping for a short time.  
• A small dip in indoor heating output for a few minutes.  

This is normal and actually protects performance in the long run.  

Backup or auxiliary heat steps in when it is extremely cold or when defrost cycles reduce output. This might be: 

• Electric resistance heaters in the air handler.  
• An existing furnace in a dual-fuel setup.  
• A boiler or hydronic system working with the heat pump.  

A well-planned hybrid system decides when to use the heat pump and when to call for backup heat based on outdoor temperature and system controls. When people talk about the best heat pump for cold weather in Canada, it is important to think about how it handles defrost, how backup heat is integrated and how smart controls manage both, not just the number printed on the rating plate.

Choosing the Best Cold-Climate Heat Pump for Ottawa

Picking the right unit starts with knowing what to look for. Some key points include:  

• High HSPF and SEER ratings that show strong heating and cooling efficiency.  
• A low ambient temperature rating that matches Ottawa winters.  
• Inverter technology for smooth, modulating operation.  
• A manufacturer with good reliability and support in our region.  

It is tempting to think that bigger is always better, but that is not the case with heat pumps. An oversized system can short cycle, which means it starts and stops too often. That can lead to:  

• Reduced comfort and uneven temperatures.  
• More frequent defrost interruptions.  
• Extra wear on components over time.  

Professional heat loss calculations help size the equipment correctly. We also look at existing ducts, radiant heating systems, electrical capacity and any future plans like finishing a basement or building an addition. Working with multiple reputable manufacturers lets us match each home or light commercial space with equipment that fits the building envelope and budget instead of forcing one solution on every project.

Practical Ways to Boost Comfort and Efficiency in Winter

Even the best equipment needs the right care and setup to perform well. There are simple habits that help your heat pump stay efficient through an Ottawa winter.  

Homeowners can:  

• Change or clean filters on a regular schedule.  
• Keep the outdoor unit clear of snow, ice and debris.  
• Make sure there is good drainage around the unit to limit re-freeze.  
• Avoid building covers that block airflow.  

Thermostat strategy also matters. Cold-climate heat pumps do best with steady, gentle operation.  

• Large temperature setbacks in deep winter can cause the system to run hard trying to catch up.  
• Using moderate setpoints and planned schedules keeps comfort more even.  
• Learning what the “aux heat” or “emergency heat” indicators mean helps you understand when backup heat is running.  

Regular professional maintenance is just as important. Cleaning coils, checking refrigerant levels, inspecting controls and testing defrost operation all support better efficiency and fewer issues. For our team at True North Mechanical, this is a key part of keeping systems reliable across many winters in Ottawa and the surrounding area.

Upgrade Your Home Comfort With Reliable Cold-Climate Heating

If you are considering a new heating system, we can help you choose the best heat pump for cold weather in Canada so your home stays comfortable all winter. At True North Mechanical, we assess your home, recommend the right model, and handle the full installation with attention to detail. Reach out today to discuss your options and get a straightforward quote tailored to your space.