Running costs depend on your home, heating system, electricity tariff and the boiler you’re replacing. Heat pumps are highly efficient, but electricity usually costs more per unit than gas. In our example, an air source heat pump costs less to run than an older, inefficient gas boiler, but more than a new efficient gas boiler. A well-designed system, suitable radiators, good insulation and the right tariff can all help keep running costs down.

A heat pump needs some space. The main unit sits outside, with clear space around it so air can flow. You’ll usually need room indoors for a hot-water cylinder too. The outdoor unit makes a quiet sound, a bit like a fridge. You may notice it more when it works harder in cold weather, but you shouldn’t normally hear it inside your home.