Consumer review group Stiftung Warentest compares air/water heat pumps: The winner is Viessmann’s Vitocal 250-A
Stiftung Warentest is a German consumer organisation and foundation involved in investigating and comparing goods and services in an unbiased way. It was founded on 4 December 1964 by the Federal Republic of Germany as an independent foundation under civil law. It is based in Berlin.
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