Can air conditioning heat a house?

Most modern split air conditioners are reverse-cycle heat pumps, often called air-to-air heat pumps. In winter they run in reverse, taking heat from the outside air and releasing it indoors, so the same unit can cool in summer and heat in winter.

Heating efficiency is shown as SCOP (seasonal coefficient of performance). A SCOP of 4 means that, over a typical heating season, the system delivers about 4 kWh of heat for every 1 kWh of electricity it uses.

Many modern wall-mounted units have a SCOP between 3.5 and 5. Compare the SCOP figures on the quotes you get, as well as the price. Our running costs guide compares the cost per unit of heat with gas and electric heaters.

Yes, but heat output and efficiency drop as the outside temperature falls. Many current units are rated to keep heating well below freezing. In cold, damp weather the outdoor unit will pause briefly from time to time to defrost itself, which is normal.

It can heat the rooms that have an indoor unit. Whether it can replace your existing heating depends on a few things:

• Air-to-air systems don’t heat water, so you’d still need a separate way of heating hot water.
• Rooms without an indoor unit, such as bathrooms and hallways, only get heat that spreads from the rooms around them.
• The heat loss of each room decides how much capacity it needs, and older, less-insulated homes need more.
• Your electrical supply needs to be able to handle the extra load.

Many households use air conditioning to heat the rooms they use most and keep their existing system for hot water and backup heating.

An installer needs to see the property to work out heat loss room by room, where units can go, and whether the electrics are suitable. Until then, nobody can say whether a system will be enough. Send an enquiry to arrange one.