Do Air Source Heat Pumps Work in Cold Weather?
Heat pumps can be a great alternative to gas or oil boilers, but if you live in a cold climate, you may be concerned that this type of system won't heat your home efficiently. In fact, this is not the case.
Heat pumps work by using natural heat that can be found in the ground, air, or groundwater around your home. Therefore, unlike other heating appliances, they do not use fossil fuels to heat your home and can reduce carbon dioxide emissions that can be harmful to the environment. This makes them increasingly popular among homeowners who are conscious of the ecosystem and want to use more renewable energy.
But what if you live in a cold climate? Temperatures can drop to around -10°C in winter. You might be wondering, how can there be enough heat in the ground or in the surrounding air to heat your home? We've answered this question and more in this helpful article, so keep reading to learn more.
How a heat pump works?
Heat pumps use heat from the air or the surrounding ground as the primary energy source. They use a small amount of electricity to extract this energy from the surrounding environment and into a heat exchanger, sometimes called an evaporator. Inside this heat exchanger, heat is absorbed by the refrigerant, which evaporates and turns into a gas. Refrigerants absorb heat even at extremely low temperatures of -20°C, which is why heat pumps are able to work in cold climates.
This evaporated refrigerant is then compressed, which further increases the temperature. The gas can then transfer its heat to your home's central heating system. When this happens, the refrigerant gradually cools until it condenses into a liquid again. This happens in the second heat exchanger, also known as the condenser. Inside the condenser, the cooler water from the central heating system can continue to absorb any heat, which is then delivered to your home through any radiators or underfloor heating. Alternatively, it can be used to supply hot water to your faucet through the cylinder.
Finally, the cooler refrigerant passes through the expansion valve. The pressure drops, the refrigerant returns to the evaporator, and the whole process starts all over again.
How good is a heat pump in cold weather?
Now that you know how a heat pump works, you may still be wondering how the system gets heat from the ground or from the air when the temperature is below zero.
The ground temperature will usually not fall below 10 °C. While this may not be warm to us, a heat pump can still absorb some heat to warm your home. Even with an air source heat pump, ambient heat can be used. Remember that Celsius is an artificial scale, and zero degrees does not mean that there is no heat in the air at all. If the heat is zero, the temperature of the earth will reach -273.
As long as you buy the right one, your heat pump will keep working in cold weather. Every heat pump is different and you will need the right equipment to ensure your home can be heated throughout the winter.
How efficient is a heat pump in cold weather?
Your heat pump won't work as well in colder temperatures as it will in milder conditions. More power may be required to remove heat from the air, which leads to lower efficiency.
Heat pump efficiency is measured using the coefficient of performance (CoP). This is calculated by comparing the input quantity with the output quantity. For example, if an air source heat pump uses 1 kW of electricity to generate 3 kW of heat, the CoP is 3. The higher the CoP, the better, as it indicates that your heat pump is more efficient.
If you do live in a very cold climate, you may benefit more from a ground source heat pump. This is because the ground temperature tends to be higher than the air temperature. Therefore, a ground source heat pump may require less electricity to operate and can generate more heat.
With an outside temperature of 8.3 °C, your heat pump can achieve around 3.8 CoP. However, if the temperature drops to around -8.3 °C, your heat pump efficiency may drop to around 2.3 CoP. If the outside temperature drops too low for your heat pump to generate any heat, you may need a backup. This is unlikely to happen in the UK, however, heat pumps in countries like Canada may need to rely on backup. 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.
How to use a heat pump in winter?
During the winter months, although it may feel cold outside, an air source heat pump is still able to use it to generate heat for your property's central heating system.
These 7 tips will help you get the most out of your air source heat pump in winter.
1. Do not cover the heat pump
If you cover the air source heat pump, the airflow is blocked, which will reduce the efficiency of the heat pump and may even lead to mold.
2. Get a smart thermostat
Having a smart thermostat will make it easier for you to control your central heating, which will help lower your energy bills.
3. Remove leaves, snow and other debris
If the area around it fills with leaves, snow, or other debris, the airflow will be blocked and the heat pump's efficiency will begin to drop.
4. Make sure your home is well insulated
A heat pump can efficiently heat your home, but if the home is poorly insulated, the heat can escape, which means you only have to heat the home for longer, increasing your energy bills.
5. Switch to cheaper energy providers
Air source heat pumps require electricity to operate, which can be expensive. While air source heat pumps can be around 300% efficient, switching to the cheapest tariff available will keep your bills to a minimum.
6. Consider a larger heatsink
The water heated by an air source heat pump and circulated around the heating system does not reach as high a temperature as the water heated by the boiler. Therefore, when using an air source heat pump, a radiator or floor heating with a larger surface area is the best heating system.
7. Schedule service before winter
Having your air source heat pump inspected by a fully qualified professional before winter will ensure it is operating effectively and efficiently when you need it most.
