One system for summer and winter

The outdoor unit gathers warmth from the outside air, even on a cold day, and the refrigerant carries it indoors. Because it is moving heat rather than making it, each unit of electricity can deliver three or four units of warmth in mild weather. That ratio drops as it gets colder, but stays well above a plug-in electric heater.

Warm air comes out of the indoor unit within a few minutes, so a room heats up quickly. That suits spaces used at odd hours.

Most homes here keep their gas boiler and radiators. The heat pump does the lighter work around them:

Spring and autumn

Take the chill off one room without firing up the whole house.

Garden offices

Often have no radiator at all. One unit gives heat and cooling.

Extensions

Where the existing boiler struggles with an extra room.

Conservatories

Usable in January as well as August.

Annexes

Independent comfort for a relative or lodger.

Electric-only flats

A cheaper way to heat than storage or panel heaters.

An air-to-air system warms the air in the rooms that have an indoor unit. It does not heat hot water, and it does not feed radiators or underfloor pipes. If you want to replace a boiler outright, that is a job for an air-to-water heat pump, which is a different product and a much bigger project.

Warm air also feels different from a radiator. Some people love the fast warm-up; others prefer the gentle background heat of a hot panel. If you’re unsure, ask the surveyor about floor-standing units, which push warmth out at low level.

The government’s Boiler Upgrade Scheme is aimed at heat pumps that replace a boiler and supply hot water, so air-to-air systems are not generally eligible. Rules do change, so check the current guidance on GOV.UK rather than relying on any installer’s summary, this one included.