Are Heat Pumps Efficient in Cold Weather

Heat pumps can be a great alternative to gas or oil boilers, but you may worry that if you live in a cold climate, this type of system won't heat your home effectively. In fact, this is not the case.

How heat pumps work

Heat pumps use heat from the air or surrounding ground as their primary energy source. They use a small amount of electricity to extract energy from the surrounding environment and into a heat exchanger (sometimes called an evaporator). Within this heat exchanger, heat is absorbed by the refrigerant, which evaporates and turns into a gas. Even at extremely low temperatures of -20°C, refrigerant can absorb heat, which is why heat pumps can work in cold climates.

The evaporated refrigerant is then compressed, further increasing the temperature. The gas can then transfer the heat into your home's central heating system. When this happens, the refrigerant gradually cools until it condenses back into a liquid again. This occurs in the second heat exchanger, also called the condenser. Inside the condenser, the cooler water from the central heating system can continue to absorb any heat and then pump it around your house through any radiators or underfloor heating systems. Alternatively, it can be used to provide hot water to your tap via a cylinder.

Finally, the cooler refrigerant passes through the expansion valve. The pressure drops, the refrigerant returns to the evaporator, and the entire process starts over.

How effective are heat pumps in cold weather?

Now that you understand how a heat pump works, you may still be wondering how the system absorbs heat from the ground or air when temperatures are below freezing.

In most areas, ground temperatures typically do not drop below 10°C. Although this may not feel warm to us, a heat pump can still absorb some heat to heat your home. Even with an air source heat pump, ambient heat can be harnessed. Remember, Celsius is a man-made scale and zero degrees does not mean there is no heat in the air at all. If the heat were zero, the Earth's temperature would be -273.

As long as you buy the right heat pump, your heat pump will continue to work during cold weather. Every heat pump is different, and you need the right unit to ensure your home is heated all winter long. This may not be as big a deal for most areas as some places like Canada or North America, where temperatures can drop as low as -30°C. As a Chinese manufacturer, Leomon has tested their heat pumps during harsh winters and elsewhere in Europe.

How efficient are heat pumps in cold weather?

Your heat pump won't be as effective in cold temperatures as it will be in mild conditions. More power may be required to remove heat from the air, which may result in reduced efficiency.

Heat pump efficiency is measured using the coefficient of performance (CoP). This is calculated by comparing the input quantity to the output quantity. For example, if an air source heat pump uses 1 kW of electricity to produce 3 kW of heat, the CoP is 3. The higher the CoP the better as it indicates your heat pump is more efficient.

If you do live in a very cold climate, you may benefit more from a geothermal heat pump. This is because ground temperatures tend to be warmer than air temperatures. Therefore, geothermal heat pumps require less electricity to operate but can produce more heat.

When the outdoor temperature is 8.3 °C, your heat pump achieves approximately 3.8 CoP. However, if the temperature drops to around -8.3 °C, the efficiency of the heat pump may drop to around 2.3 CoP. If the outside temperature drops too low for the heat pump to produce any heat, a backup may be needed. This is unlikely to happen in the UK, however, heat pumps in countries such as Canada may need to rely on backup power. This can get expensive, so if you live in an extremely cold climate, a heat pump may not be the most efficient way to heat your home.

If you take good care of it, your heat pump will remain efficient for longer. You should ensure that your system is maintained every 12 months. Not only will this ensure everything is running safely, but you'll also feel good knowing your heat pump will be able to keep your home warm all winter long. If you have an air source heat pump, you should clear the area of any clutter to prevent airflow from being blocked. This may reduce the efficiency of the heat pump. You may also need to check the filter regularly and replace it as necessary, any maintenance is best carried out by a qualified engineer.

Get more help

Leomon is a specialist heat pump manufacturer. If you need to purchase a cold climate heat pump, please contact us and our heat pump experts will give you the best advice.