Blowing hot and cold Air-to-air heat pumps show their worth in all seasons

When David Tester, 56, installed a heat pump in his home in the winter of 2022, freezing temperatures descended on the country alongside a series of named storms.

- Jillian Ambrose

It was a world away from this summer's heatwaves, which have pushed Britain to the brink of drought.

But Tester's choice of heat pump design has meant that his three-bedroom 1930s semi in West Sussex has remained at a comfortable temperature despite increasingly volatile weather. The air-to-air heat pump provides heating in the winter but acts like an air conditioner in the summer months.

"The heat pump has worked very well in both seasons and because I run it on electricity from my solar panels, it basically provides cooling for free," he told the Guardian.

Heat pumps remain rare in Britain, but the recent spells of hotter than average temperatures may have the unexpected consequence of boosting the government's ambition to replace Britain's boilers.

Ministers recently set out plans to include air-to-air heat pumps that can act as air conditioners in the same grant scheme that offers £7,500 to households who replace their gas boiler with "wet system" heat pumps.

So far, the government has prioritised promoting "hydronic" heat pumps, in large part because they make use of the existing central heating pipes and radiators that most households use to warm their homes.

They work like a fridge in reverse by using electricity to capture and amplify even small amounts of heat outside a home to raise the water temperature of a home's central heating system. The warmed water travels through pipes and radiators to heat a home in the same way as water heated by a gas boiler.

But these are far from the most common choice in homes across Europe, according to Prof Jan Rosenow, an academic and a programme director at the Regulatory Assistance Project, which regularly analyses heat pump systems.