What do I need to consider when changing a boiler to an air source heat pump?

You can’t just replace a boiler with an air source heat pump and expect it to work properly. You need to start by carrying out a heat loss calculation for the property and advise the homeowner of any improvements that need to be made to insulation, windows and doors. This would improve the heat loss calculations and make it more efficient to heat the home with an air source heat pump. If there isn’t already a hot water storage cylinder, you will need to install one, and if there is a cylinder in place, it may need changing, as an air source heat pump cylinder has a much larger coil inside to allow for better heat transfer and better reheat times.