How Heat Pumps Work

A heat pump operates on the same refrigeration cycle used in household refrigerators and air conditioners. A refrigerant circulates between an outdoor unit and an indoor air handler. In heating mode, the outdoor unit extracts heat from outside air (or ground) and compresses the refrigerant to concentrate that heat, which is then transferred to the indoor space. In cooling mode, the cycle reverses.

The key metric for heat pump efficiency is the Coefficient of Performance (COP)—the ratio of heat delivered to electrical energy consumed. A COP of 3 means the system delivers three units of heat for every unit of electricity used. Conventional resistance heating achieves a COP of 1 by definition; natural gas furnaces cannot exceed 1 on an energy-in versus heat-out basis at the point of use. Heat pumps routinely achieve COPs above 2 even in moderately cold conditions.

Cold-Climate Performance

Earlier generations of air-source heat pumps lost efficiency rapidly as outdoor temperatures dropped, creating a perception that they were unsuitable for Canadian winters. Cold-climate heat pumps, developed and refined over the past decade, use improved compressor designs and refrigerant formulations that maintain effective operation at temperatures well below freezing.

Several manufacturers now produce products rated to operate efficiently at outdoor temperatures reaching −25°C to −30°C, covering the winter temperature range experienced across most of Canada's populated areas. At these extremes, the COP decreases compared to milder conditions, but the system continues to deliver heat rather than shutting down. A backup resistance heating element—included in many cold-climate systems—activates automatically when temperatures exceed the heat pump's effective range.

Cold Climate Housing Research Centre (CCHRC) in Yukon and the Northern Housing Committee have documented heat pump performance in subarctic conditions. While conventional cold-climate heat pumps are viable for most Canadian provinces, homes in the northern territories require site-specific assessment.

Air-Source vs. Ground-Source Systems

Air-Source Heat Pumps (ASHP)

Air-source systems extract heat from outdoor air. The outdoor unit resembles a conventional air conditioner compressor. Installation typically involves mounting the outdoor unit on a pad or wall bracket, connecting refrigerant lines to an indoor air handler, and making electrical connections. Installation is less invasive than ground-source alternatives. Cold-climate ASHP products from multiple manufacturers are available across Canada through HVAC contractors.

Mini-split (ductless) configurations connect one or more indoor wall units to a single outdoor unit, allowing zoned heating and cooling without duct installation. These are commonly used in homes that lack existing ductwork or where adding ducts is impractical.

Ground-Source Heat Pumps (GSHP)

Ground-source systems exchange heat with the ground via a loop of piping buried horizontally (requiring significant land area), vertically (requiring drilling), or submerged in a water body. The ground temperature at depth remains relatively stable year-round—typically around 10°C in southern Canada—so the source temperature is more consistent than outdoor air. This produces more predictable performance.

Installation costs are substantially higher than for air-source systems due to excavation or drilling. The loop field requires appropriate site conditions—soil type, available area, local regulations on wells and drilling. Operating costs over time can be lower, and the buried components have a long operational life with minimal maintenance.

Integration with Existing Heating Systems

Many Canadian homes have existing gas or oil furnaces with duct systems. A common retrofit approach combines a cold-climate air-source heat pump with the existing furnace in what is called a dual-fuel or hybrid system. The heat pump handles the majority of heating demand during milder periods, and the furnace takes over during the coldest days when fuel-based heating may be economically competitive depending on local energy prices. This approach reduces fuel consumption and greenhouse gas emissions without fully replacing the existing system in the first step.

Hydronic heating systems (hot water baseboards or radiant floors) require a heat pump capable of producing water temperatures appropriate for the distribution system. Low-temperature heat pumps designed for hydronic distribution are available but represent a more specialised segment of the market.

Electricity Considerations

Heat pumps require electricity to operate. The environmental and economic case for heat pumps depends partly on the emissions intensity of the local electricity grid. In provinces with predominantly hydroelectric generation—Quebec, British Columbia, Manitoba—switching from gas heat to an electric heat pump delivers substantial greenhouse gas reductions. In provinces where electricity is generated primarily from natural gas or coal, the calculation is more nuanced and depends on relative efficiency gains and local fuel and electricity prices.

Adding a heat pump to a home increases the electricity load, which may require an electrical panel upgrade depending on existing capacity. A licensed electrician should assess the panel before installation.

Provincial Rebate Programs

Several provincial and federal programs have offered incentives for heat pump installation. The federal Canada Greener Homes Initiative has provided grants for qualifying cold-climate heat pumps. Provincial programs include Efficiency Nova Scotia, Efficiency New Brunswick, Hydro-Québec's rebate program, BC Hydro and FortisBC rebates in British Columbia, and programs through Energy Efficiency Alberta. Program terms, eligible products, and rebate amounts change; verifying current availability directly with the relevant agency before finalising equipment selection is important.

Sizing and Contractor Selection

Proper sizing of a heat pump requires a Manual J or equivalent heat load calculation for the specific home. An undersized unit cannot maintain comfort in peak conditions; an oversized unit short-cycles, reducing efficiency and increasing wear. Contractors should perform a load calculation rather than sizing based on existing equipment alone.

Heat pump installation in Canada requires a licensed refrigeration mechanic (or equivalent designation depending on province) for refrigerant handling. Confirming contractor licensing and asking for references from heat pump installations—not just air conditioning work—provides useful assurance of relevant experience.

Maintenance Requirements

Air-source heat pumps require periodic filter cleaning or replacement, clearing of debris from around the outdoor unit, and annual refrigerant system checks by a qualified technician. The outdoor unit accumulates frost during certain temperature and humidity combinations and has a defrost cycle that handles this automatically. Ground-source systems have fewer outdoor components exposed to weather but require loop system pressure monitoring and heat exchanger maintenance on the same schedule.

Realistic Expectations

A heat pump installation in a reasonably well-insulated Canadian home typically reduces heating energy consumption meaningfully compared to older resistance electric heat or mid-efficiency gas equipment. The exact reduction depends on the starting equipment, the specific heat pump model, local climate, and occupant behaviour. Independent data from field studies in Canadian climates is available through Natural Resources Canada's research publications and can provide a realistic baseline for expectations before committing to a project.