Many UK shoppers think of air conditioning as a summer-only product. In reality, a large proportion of modern split air conditioners are reversible heat pumps: they can move heat out of the room in cooling mode and move heat into the room in heating mode.

This type of system is commonly called an air-to-air heat pump. Instead of generating heat directly like a resistance heater, it transfers heat using a refrigeration cycle. Under suitable conditions, it can deliver several units of heat for each unit of electricity consumed.

The efficiency of heating is often described by COP for a particular operating point and SCOP for seasonal performance. A higher SCOP generally indicates better seasonal heating efficiency, but actual performance depends on outdoor temperature, indoor set point, installation and usage.

For UK homes, air-to-air systems can be attractive for targeted heating. A home office, bedroom, garden room or living area can be heated without necessarily heating every room in the property. They can also provide rapid warm air when the room is first occupied.

There are limitations. Heating capacity and efficiency can fall as outdoor temperatures become more demanding, and the outdoor unit may periodically enter a defrost cycle in cold, damp conditions. Buyers should check the manufacturer’s operating range and heating-capacity data rather than assuming nominal performance is constant.

Comfort is different from a radiator system. Air-to-air heat pumps warm the room using moving air, so indoor-unit placement and fan speed affect how the heat feels. Some people appreciate the rapid response; others prefer the radiant character of traditional heating.

Running-cost comparisons need care. Electricity and gas prices change, tariffs vary and boiler efficiency differs from property to property. Compare useful heat delivered, not simply the price per kWh of electricity versus gas.

Air conditioning is therefore not automatically a replacement for central heating, but heating capability can add significant year-round value to a system purchased primarily for summer cooling.

When shopping, filter for ‘heating + cooling’ and compare SCOP, heating capacity, low-temperature operating range, sound level and controls. Our AC Finder can prioritise reversible systems if winter heating is one of your requirements.