Why is hot waste water (shower, sink…) not reused for heating?

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Why is it not used again and wouldn’t it be very efficient to combine with a heat pump for reuse?
Especially since water from shower or sink isn’t usually very dirty, couldn’t it be stored for a while in an isolated tank so that e.g. a heat pump can run more efficient on it than on usually colder air or colder ground water?

In: Engineering

27 Answers

Anonymous 0 Comments

Usually it’s not economically viable. You can’t really use the dirty water directly due to particles and residue building up in heating equipment, and heat exchangers are quite expensive compared to simpler heating devices. Also, water used for heating is 1.5 to 2 times hotter than waste shower water – e.g. 60-80 C vs 40 C.

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