Is heating with air conditioning cheaper than gas?
Per unit of heat, a modern split system delivers roughly three kilowatts of heat per kilowatt of electricity, which brings its running cost close to mains gas and far below any plug-in electric heater. For heating one room in spring and autumn instead of firing the whole boiler, the air conditioner usually wins outright.
Every split system we install is an air-to-air heat pump: reverse the cycle and it moves heat from outside air into the room, even on cold days. The efficiency number that matters is the coefficient of performance, typically 3 to 4 for modern units in mild UK winters, meaning three to four kilowatts of heat per kilowatt of electricity bought.
Against electric heaters there is no contest: a fan heater gives one kilowatt of heat per kilowatt bought, so the split heats the same room for roughly a third of the cost. Against mains gas the arithmetic is closer. Gas costs around a quarter of electricity per kWh, but a boiler is only about 85 to 90% efficient and heats a whole circuit of radiators to warm one room.
Where the air conditioner clearly earns its keep is zonal heating: the home office through a working day, the bedroom in October before the heating season properly starts, the loft room the radiators never quite reached. Heating one room precisely instead of the whole house approximately is where the savings are real.
We size and position units for cooling first, because that is why people call us. The winter heating is the quiet bonus: most of our customers tell us a year later they use it more than they expected.
More in costs & running costs, or browse all 40 questions on the FAQ index.
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