Can heat pumps be used in winter?
As winter sets in, it becomes important, even crucial, to choose the right heating system in order to be warm when the temperature is at its lowest. If the heat pump proves to be an excellent compromise throughout the year thanks to its dual function of heating and cooling, the question arises as to its effectiveness in the middle of winter. Learn more about heat pumps and how they work in this article.
What is a heat pump and how does it work?
The heat pump is a device that can both heat and cool by using mainly the heat contained in the air. Thus, it keeps the house at an adequate temperature both in winter and in summer.
The operation of a heat pump is both simple and complex. It has a liquid refrigerant contained in two serpentine pipes which is compressed by a compressor. When the heat pump is in heating mode, the refrigerant is delivered to the outdoor coil as a gas. The latter will then be brought back to the inner coil and compressed. This will raise its temperature. This heat will then be diffused by a fan to heat the rooms of the house.
Although the heat pump can act as an air conditioner, it does not produce cold. In fact, when it is in air conditioning mode, it extracts the heat present in the air inside the rooms and expels it outside. The cooler air is then distributed throughout the house.
But the other quality of the heat pump is its ability to improve the air quality in the house by reducing its humidity. In other words, it performs three functions: heating, cooling and dehumidifying.
How efficient is a heat pump in winter?
As you can see, the heat pump is a very versatile device that is useful in both summer and winter. But the real issue is the ability of the heat pump to meet the heating needs of a home when the temperature is at its lowest in the winter. Is it sufficient or should other heating systems be installed as backup?
Notion of coefficient of performance
To answer this question, it is important to talk about the coefficient of performance. This is a number indicating the performance of a given device at a given temperature. The coefficient of performance or COP will therefore determine the efficiency of a heat pump according to the outside temperature.
Normally, this efficiency decreases linearly as the temperature drops. Here is a very simple example: for an appliance indicating a CP of 2 means that 1 kWh of electricity must be used to produce the equivalent of 2 kWh of heating.
What is the coefficient of performance of heat pumps?
According to the Office of Energy Efficiency of Natural Resources Canada, the average heat pump offers a CP of 2.3 at a temperature of -8°C. When the temperature reaches -15°C, the CP drops to 1.
For areas located in southern Quebec, standard heat pumps are sufficient to meet the needs of homes year-round. On the other hand, for areas located further north where temperatures are well below freezing, conventional heat pumps find their limit.
Heat pumps better adapted to cold weather
In recent years, the technologies used in the design of heat pumps have evolved significantly, resulting in much more efficient models at lower temperatures. For example, some models offer a CP of up to 1.5 at temperatures around -21°C.
To achieve such efficiency, these new heat pump models are larger to accommodate a larger heat exchanger and a more efficient compressor. Most of the time, the unit will run at low speed and will only be fully used during periods of extreme cold.
These more powerful heat pumps are logically more expensive, but they can meet heating needs even in the coldest areas of Canada without the help of other heating systems.
How to prepare a heat pump for winter?
If you want your heat pump to be able to perform its role fully during the winter, it is important to perform maintenance and take preventive measures. Here are some tips that may be helpful.
Clear the area around the outdoor unit
Optimize airflow around your heat pump’s outdoor unit before the cold weather arrives. Dead leaves, weeds and any obstructions that may block airflow should be removed.
Change the filters on the heat pump
If your heat pump filters are starting to age, now is the time to replace them before temperatures drop significantly. A dirty filter makes it difficult for air to circulate, which puts more strain on your heat pump and increases your energy consumption.
Check the operation of your heat pump
It is important to test the operation of your heat pump before the cold weather arrives. To do this, check to see if the unit is delivering warm air when the thermostat is set to this function. Also look for odors, especially mold. This indicates that the filters are very dirty and that bacteria have developed in the unit.
Have your heat pump inspected by a professional
There is nothing like the eyes and know-how of a seasoned professional to detect any problem on your heat pump. It’s better to find anomalies before the cold weather arrives than to be caught off guard when it does. By anticipating your maintenance, you can ensure peace of mind all winter long regarding your heating solution.
Duct cleaning
Ductwork also plays a role in the quality of the air that circulates in the home. When you have your heat pump inspected, take the opportunity to have your specialist inspect and clean the ducts.