Do air source heat pumps work in the UK?

If you’re looking into investing in an air source heat pump for your home, you’ll likely have seen that they work by extracting heat from the outside air and releasing that heat into your house – primarily through normal domestic radiators.

But if they extract heat from the outside air, how can they extract heat when there isn’t any in the outside air? After all, it doesn’t usually feel that hot in the UK!

While it doesn’t often feel like there’s enough heat in the air, appropriately-sized ASHP systems certainly do work in the UK.

Here’s why:

• It doesn’t need to be ‘hot’ for heat pumps to work
• Heat pumps can work down to really low temperatures

It’s crucial to understand that the weather doesn’t need to be hot for heat pumps to work – the idea that they can only work in hot temperatures is a similar misconception to the idea that solar panels can only work when it’s really sunny.

Heat pumps work by creating a temperature difference between an internal refrigerant and the air outside your home; they make the liquid refrigerant turns to a vapour at really low temperatures.

This can be adjusted through pressure so that it is able to take on the difference in temperature all year round.

The higher the outside air temperature, the more efficiently the heat pumps will be able to operate.

So the cost of hot water for taps, baths, and showers, ends up a lot cheaper during the warmer summer months!

If you’re curious about the technical details of how heat pumps work, read more about that here.

Because they work using the temperature difference between the refrigerant and the ambient air, heat pumps can work down to really low temperatures.

Technically, they can work down to -28°C – it’s why they’re so popular in Scandinavia – but  MCS-registered UK installations are sized to work efficiently based on the geographical location of your home.

Because we only experience below-zero temperatures (at most) for a few days a year, installing a system that can operate efficiently at temperatures lower than MCS design temperatures adds significant cost and reduces efficiency over the rest of the year.

Crucially, your heat pump will still continue to work if we happen to get a sudden cold snap – so you’re not going to be left without heating on the coldest day of the year – it just won’t be able to work as efficiently as it does over the rest of the year. In other words, it’ll use a bit more electricity than it usually does.

The only possible downside of getting an air source heat pump for a UK domestic property is that you’ll need adequate space  – so ASHPs aren’t often suitable for all properties.

If you have a garden or outside area, an existing hot water cylinder or space to fit one however, an ASHP could be a great investment into dependable, sustainable heating.