Heating
Heating with an air conditioner in winter: does it work and is it worth it
Winters in Gabrovo, Troyan or Veliko Tarnovo are serious, and more households heat with an air conditioner every year. Does it really work at −15°C, what does it cost and which models are built for winter?
5 min readUpdated
How it heats below zero
An air conditioner is an air-to-air heat pump: even at −15°C the outdoor air holds heat the compressor moves indoors. Output and efficiency fall with temperature. Modern inverters are rated to −15°C; "hyper inverter" series (Mitsubishi Electric Hyper Heating, Daikin Perfera, Toshiba Daiseikai and others) work to −25°C with near-full output down to −15°C.
Three numbers that decide
Heating output at −7°C (in the technical data, rarely on the label), SCOP (ideally above 4.3) and the minimum operating temperature. The nominal heating figure is measured at +7°C and says nothing about cold days.
What it costs
A 30 m² living room with a 12000 BTU inverter and SCOP 4.6 uses about 700–900 kWh per winter, 100–140 € at 0.15 €/kWh. A resistive heater would cost 4–5 times more.
When it is not a good primary heater
Whole houses with several closed rooms: warm air does not pass through walls. Then it is a multi-split, a ducted unit or an air-to-water heat pump. Uninsulated mountain houses with long spells below −15°C need a backup source for the coldest days.
Using it right
Point the louvers down, set 21–22°C and keep it running rather than switching off for hours. Defrost cycles every 40–90 minutes are normal. Clean the filters every 2–4 weeks in the heating season.
Frequently asked questions
Down to what outdoor temperature does heating work?
Standard inverters to −15°C; winter series with hyper inverter to −25°C while keeping near-full output to −15°C.
What is a hyper inverter?
A trade name for compressors with vapour injection and a stronger inverter that keep heating output at very low temperatures: Zubadan, Hyper Heating, Nordic or Arctic series.
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