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Heat pump in Berlin

Photo: Doreen Garud / dpa

The image of the heat pump is still too expensive to buy and use – and unsuitable for most older houses in the portfolio. Wrongly, emphasizes Stiftung Warentest in the conclusion of a heat pump test (click here for the test report).

Accordingly, many devices are convincing, even if there are still considerable differences in operating efficiency and the heat agents used. This is the conclusion reached by Warentest after examining a total of six air-to-water heat pumps. Four devices scored "good", two received the grade "satisfactory".

"All six models can heat a single-family home," say the testers. The biggest differences would be in power consumption. While the most efficient pump in a mediocre insulated 140-square-meter house consumes less than 5000 kilowatt hours per year, the taillight requires more than 6500 kilowatt hours. At an electricity price of 40 cents per kilowatt hour, this makes cost differences of around 600 euros per year.

Problematic refrigerant

In addition, the refrigerant used played a role in the evaluation. The two heat pumps, which were rated satisfactory, used the potentially climate-damaging agent R32. According to the testers, if it were to escape, it would have the same greenhouse effect as 2.2 tonnes of CO₂. The use of the agent is not necessary because the climate-friendly propane is an alternative that has even led to better energy efficiency for two manufacturers.

When it came to volume, four pumps were rated "good" and two were rated "satisfactory". Before installation, however, you should check how much distance the pump has to keep from the neighboring property and how it is aligned," the product testers advise. In addition, soundproof hoods and feet against strong vibrations are an option.