Understanding the limits of central heat pumps during extreme cold periods
When living in a region like Montréal, Laval, Longueuil, the North Shore or the South Shore, winter means freezing temperatures that can push any heating system to its limits. Among the most popular solutions for efficiently heating a residential or commercial building, the central heat pump stands out. But when the mercury drops to -20°C, -25°C, even -30°C, a very valid question often comes up with our customers: is the central heat pump enough, or do you need a backup heating system during deep freezes?
At AirGreen, we've encountered this situation countless times, and our on-site expertise allows us to provide clear answers, based on real cases, technical data, and a deep understanding of how HVAC systems operate during Quebec winters.
Why can central heat pumps lose efficiency in extreme cold?
Central heat pumps work by transferring heat, capturing energy from the outside air to redistribute it indoors. But when the outside temperature drops sharply, the available energy in the air becomes minimal. The result: the unit must work harder to provide the same thermal comfort, which can lead to:
-
A drop in performance.
-
An increase in energy consumption.
-
More frequent defrost cycles.
-
Temporary discomfort inside the building.
Do new high-efficiency models make a real difference?
Absolutely. The latest generations of central heat pumps, such as those from Fujitsu, Gree, Lennox, Bosch or Trane, are engineered to operate even in extremely low temperatures. For example:
-
The Bosch BOVA 20 SEER central heat pump with R-454B refrigerant can maintain heating performance down to -25°C while offering superior energy efficiency.
-
The two-stage Fujitsu system allows the power to adjust according to outdoor conditions, reducing the need for a backup.
However, even the best units have a limit to their operating range. That’s where the addition of a backup heating system becomes relevant.
When does a backup heating system become necessary?
Here are some typical situations we’ve encountered during our installations across Greater Montréal:
-
Temperatures below -25°C sustained over several days.
-
Poorly insulated buildings or those with large air volumes, such as cathedral ceilings.
-
Older or undersized central heat pumps.
-
Specific comfort needs, such as for elderly occupants, young children, or people sensitive to cold.
In these cases, we always recommend a backup system, often in the form of electric resistance heating integrated into the furnace or a standalone forced-air heating system that activates automatically when the heat pump reaches its limit.
Case study: installation of a Gree central heat pump in a home in Laval
Recently, at AirGreen, we installed a 3-ton Gree Flexx central heat pump with auxiliary electric coil in a 2,300 square-foot home in Laval. The home, while well insulated, had significant heat loss through basement windows.
Our approach:
-
Integration of a 15 kW electric heating kit into the furnace.
-
System programming to ensure the backup only activates below -22°C, with no manual intervention.
-
Result: the family enjoys stable comfort all winter long, with an energy bill reduced by nearly 20% compared to their old oil system.
What types of backup heating systems are compatible?
Depending on the HVAC setup in place, several options are available:
-
Electric resistances integrated into the warm-air furnace: the most common solution.
-
Electric or gas boilers: often used in larger commercial buildings or duplexes.
-
Wood or gas stoves: a temporary backup solution in some country homes.
-
Smart hybrid systems, like those from Bosch or Lennox, which automatically switch between heat pump and backup based on the outdoor temperature.
Optimizing the efficiency of a central heat pump in winter
Even if your heat pump is a next-gen model, certain practices can boost its performance during cold spells:
-
Annual preventive maintenance of both indoor and outdoor units, ideally done in the fall.
-
Efficient manual or automated defrosting.
-
Checking airflow within the ductwork.
-
Insulating ducts located in unheated spaces (e.g.: attics, basements).
At AirGreen, we offer full HVAC maintenance services to ensure optimal year-round performance, even during extreme cold snaps.
Should you worry about a breakdown if the heat pump fails in winter?
This is a common concern, especially in rural areas of the North Shore or on the South Shore, where temperatures can drop extremely low. A properly integrated backup heating system acts as a reliable safety net, ensuring:
-
The safety of the occupants.
-
Protection of home infrastructure (plumbing, flooring).
-
Consistent minimum indoor temperatures.
We also recommend our clients opt for a service contract that includes priority access to our 24/7 technicians in case of breakdown.
Conclusion: a strategic decision to be made with your HVAC installer
The decision to integrate a backup heating system with a central heat pump depends on many factors: home insulation, comfort needs, budget, lifestyle habits, and of course, geographic location. At AirGreen, we evaluate every situation individually, to offer an HVAC solution that is durable, energy-efficient, and perfectly adapted to your winter reality.
Whether you're in Montréal, Laval, Longueuil, the North Shore or the South Shore, we’re here to guide you every step of the way — from system design to installation, and ongoing maintenance of your equipment.
Trust our expertise to keep you comfortable, even in the coldest weather.