Status: 05/05/2023 05:00 a.m
Air conditioners can also heat. They are standard in Scandinavia and southern Europe, but rather rare in Germany. They blow hot air into a room and use electricity efficiently.
It’s like the sound of the sea, thinks Wolfgang Antonius Musolf from Fahrdorf near Schleswig. “You have the feeling that you are somewhere on the Baltic Sea. But at some point it switches off again.” A long box hangs in his living room, and lukewarm air flows out of its flap. The outdoor unit with a large fan hangs outside on the other side of the wall.
Little effort during installation
The small box to the left of the window circulates and heats the air in the living room.
30,000 euros, 100,000 euros, half a million euros – in the discussion about replacing the heating system, adventurous sums are sometimes mentioned that are said to be necessary to install an air-water heat pump. The costs skyrocket when radiators have to be replaced or renovation work is required in old buildings so that heat pumps can work efficiently. With the air-to-air heat pump, often also referred to as an air conditioner, the entire heating water circuit is eliminated. Instead, the air circulates in the room and is heated directly. This simple solution is correspondingly cheaper.
Inexpensive addition to district heating
The air conditioner can be controlled by remote control.
Wolfgang Musolf decided to install it last autumn. Until now, he has heated his semi-detached house from the 1990s entirely with district heating: “We got this drastic price increase,” he recalls. District heating in Fahrdorf costs more than 30 cents per kilowatt hour of heating energy for the whole of 2023, a fourfold increase. There is a price brake. However, as with the electricity price, a fixed amount is charged. The high district heating price counts for the entire new demand.
Air conditioning only for the living room – the rest remains unchanged
A complete heating changeover was too expensive for the computer expert. An Internet video of a tinkerer heating an old farm with air conditioners made him curious. Now he heats his living room with the air-to-air heat pump. District heating continues to be used on the less-used upper floor, but on the back burner.
Fitters are busy
“A one-room solution with a small device – we might start at 4,500 euros,” says refrigeration technician Jörn-Ole Nissen from Viöl (Nordfriesland district). Until now, he has mainly served commercial customers with his company Kälte-Klima-Nord. Refrigeration technicians specialize in air conditioning units, while heating engineers hardly offer them. For the air conditioning units in the private customer business, however, he has hardly any free capacity, says Nissen. He estimates it’s similar across the industry.
According to the manufacturer, efficiency is comparable to that of air-to-water heat pumps
The efficiency of the air conditioners can keep up with air-to-water heat pumps. According to the manufacturer, the air conditioner produces five times as much heat energy from one kilowatt hour of electricity in the ideal case, and about three times as much when there is a slight frost.
This puts the heat price at 10 cents per kilowatt hour – comparable to the currently cheapest new gas contracts. But gas is likely to become more expensive again in the medium term due to the price of CO2. Heating with electricity, on the other hand, protects the climate if it is generated with wind and solar energy.
Five air conditioners replace complete gas heaters
In Husum, Norbert Paisen also uses its own solar power for its air-to-air heat pumps.
Another customer, Norbert Paisen from Husum (North Friesland district), immediately took the big step in his single-family home, which was also built 25 years ago. His gas heating will soon be disconnected: “It’s a 160 square meter house, there are five fan units in it. The fun was 18,000 euros. Half the price of an air-water heat pump,” he says.
You can also chill
The outdoor unit of the air conditioner is no different from an air-to-water heat pump. Jörn-Ole Nissen installed them.
The result: a few cable ducts run along the outer wall. There are two outdoor units. But that doesn’t bother him, nor does the quiet interior noise and the air movement – on the contrary: “I’m a smoker. I often air the air here. That’s why the air-to-air heating was ideal. You can use it to keep five to ten degrees within Reheat for 15-20 minutes with no problems.” And last but not least, the air conditioning systems can of course also cool in summer.
Heating engineers are skeptical
Paisen also reports significantly reduced consumption costs. Two of the heating engineers surveyed advise against this solution and rather recommend the large air-water solution. The Schleswig-Holstein consumer center still has little experience and refers to the information in the Efficiency House Online service portal. There are many advantages mentioned. But it is also said that the air-to-air heat pump is only suitable for energy-saving houses. The cases in Fahrdorf and Husum are not specially renovated houses. And it still works.
Funding is on hold
There are blemishes. Funding for the devices has been suspended since the beginning of the year, probably only temporarily, reports Nissen’s partner Dennis Jacobsen. The reason is that energy suppliers cannot switch off the air-to-air heat pumps when the network is overloaded. But this function could certainly be retrofitted soon.
AUDIO: Heat pumps: environmentally conscious, but long delivery times (4 min)
Refrigerant harmful to the climate if it escapes
Another aspect: the refrigerant, i.e. the substance that circulates in the hoses between the outdoor and indoor units, is particularly harmful to the climate. According to Nissen, alternatives such as propane in the newer air-water heat pumps are not yet available for the air-conditioning units. If the refrigerant escapes, that corresponds to the emissions of heating with gas for a good year. However, the air conditioning technician emphasizes: “It is a hermetic system. When the system is dismantled, the refrigerant must be extracted and recycled.”
Hot water for an extra charge
Of course, rooms without an indoor unit stay a little cooler. “The guest toilet is already quite shady. So I’m considering putting an infrared radiator on the ceiling,” says user Paisen. For hot water, too, the question arises as to whether an inefficient, cheap instantaneous water heater is more worthwhile, or investing 4,000 euros in a hot water unit with a heat pump. Both are possible and depend on personal consumption behavior.
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