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Do air source heat pumps work in winter?

Air source heat pumps are an energy-efficient way to keep your home warm during the colder months. But how do they work in winter? Here’s everything you need to know.

Do heat pumps work in cold weather?

Air source heat pumps are designed to keep going even when temperatures drop below 0°C. Systems can work as low as -25°C, while ground source heat pumps provide consistent warm air all year round. Plus, they’re still three times more efficient than boilers and can turn electricity into much more heat.

It might cost a bit more upfront than some other heating methods but there should be plenty of savings to enjoy in the long run. Additionally, if you’re looking for an extra layer of warmth you could always supplement your system with an additional heater.

At what temperature do heat pumps stop working?

For certain brands and models, you can expect their efficiency to decrease at temperatures around -18 to -22°C. However, some models may remain efficient up to -25°C.

How to prepare a heat pump for winter

Preparing your heat pump for winter is essential to ensure it operates efficiently and effectively during the colder months. Here are some steps to help you get your heat pump ready for winter:

Clean and Clear the Area: Remove any debris, leaves, or obstructions that may have accumulated around the outdoor unit of your heat pump. This helps ensure proper airflow and prevents damage caused by debris getting stuck in the unit.

Inspect and Clean the Coils: Check the outdoor unit's coils for dirt, dust, or debris. If they are dirty, gently clean them using a soft brush or hose. Dirty coils can hinder heat transfer and reduce the efficiency of your heat pump.

Check and Replace Air Filters: Inspect the air filters in your heat pump system and replace them if they are dirty or clogged. Clean air filters help maintain indoor air quality and improve the heat pump's efficiency.

Test the Thermostat: Ensure that your thermostat is functioning properly and set it to a suitable winter temperature. Test the heat pump's heating mode to make sure it activates and produces warm air.

Insulate Exposed Pipes: Insulate any exposed pipes or refrigerant lines to prevent freezing and potential damage. Use pipe insulation or heat tape to protect them from the cold temperatures.

Clear Drainage Channels: If your system has a drainage system, check for any clogs or obstructions. Clear any debris to ensure proper drainage and prevent water damage or freezing.

Try underfloor heating: If you have an air source heat pump, you may want to consider adding underfloor heating to your home. This can provide extra warmth and comfort during the winter months.

Can air source heat pumps freeze?

Air source heating systems are designed to operate in cold weather conditions, with built-in mechanisms to prevent freezing. However, it is still possible for an air source heat pump to freeze under certain circumstances.

In such situations, the heat pump may enter a defrost cycle to prevent freezing. During defrost mode, the system switches to cooling mode and redirects the flow to melt any ice on the outdoor coil.

If the outdoor coil gets covered with ice or snow, it can hinder the heat transfer process and reduce the heat pump's efficiency. To prevent this, it's important to regularly maintain the heat pump and remove any debris, ice, or snow that may accumulate around the outdoor unit.

How to defrost your heat pump unit

Air source heating functions efficiently to provide comfortable heating and efficient energy output. However, as temperatures drop outside in cold climates they are prone to frosting up, triggering a defrost cycle which can cause slight drops in temperature. This is nothing to worry over if the temperature returns to normal shortly afterwards.

If your heat pump is not producing sufficient heat, it may be that the defrost cycle is lagging and not turning on correctly.

The defrost cycle must kick into high gear when needed. So check to make sure your unit isn't still trying to defrost itself.

Regular maintenance of the outdoor airflow by cleaning coils and checking filters will help you get through cold spells with no interruption in service from your heat pump.

If you have any questions or need assistance finding the right solution for your home, please feel free to contact us. You can reach us by phone at 01392 979450 or by email at We would love to hear about your project and help you in any way we can.