In a few weeks’ time, what the government hopes will trigger a home heating revolution will begin, with a £5,000 grant being offered from this April to those who swap their gas boiler for a low-carbon heat pump. And while it’s estimated the grant scheme will cover only around 30,000 homes, this represents just the tip of the iceberg of the government’s ambitions: it has set a target of 600,000 heat pumps to be installed by 2028.

But that will be challenging.

The cheapest heat pump is an air source heat pump, but even then full system installation can cost – depending on aspects such as the size of the home and the complexity of the installation – up to £18,000.