With the Boiler Upgrade Scheme making its second anniversary, applications increased 93 per cent in April, compared to the same month last year.
The increase is led by by offers from energy suppliers which can make some heat pump installations a similar price to fitting a gas boiler, along with the introduction of cheaper electricity tariffs.
Heat pumps work by capturing heat from the air, ground or water to provide provide heating and hot water without using fossil fuels and are three times more efficient than gas boilers.