Shower water heat pump

Ator · 01-14-15, 10:35 AM

I have been lurking the forums for a while and enjoy the cool DIY going on here. I'm always busy with some small projects here and there, but now I've found that I need some more input than just my own.

I want to start working on heat recovery from my shower water. In my house it is impossible to mount a vertical unit and horizontal units lack efficiency. Building a horizontal unit myself would not pay itself back for many years.

Therefore I was thinking about using a heat pump to recoup the heat from outgoing shower water. The outgoing water is about 35 degrees centigrade and incoming in winter about 10 degrees. At 6 litres a minute the amount of heat that would need moving is some 12.5 kW, back to the original 10 degrees.

For me there are 2 options, either a compressor heat pump or Peltier cells. Of course Peltiers are known for their low efficiency, but with no moving parts, low cost and small size very practical. Of course the question is, am I better off re-purposing an old dehumidifier/AC unit or going for the Peltier units. What kind of COP can I be expecting to achieve with either of the methods and is it worth starting this ?

01-14-15, 10:35 AM	#1
Ator Lurking Renovator Join Date: Jan 2015 Location: Netherlands Posts: 25 Thanks: 1 Thanked 7 Times in 7 Posts	Shower water heat pump I have been lurking the forums for a while and enjoy the cool DIY going on here. I'm always busy with some small projects here and there, but now I've found that I need some more input than just my own. I want to start working on heat recovery from my shower water. In my house it is impossible to mount a vertical unit and horizontal units lack efficiency. Building a horizontal unit myself would not pay itself back for many years. Therefore I was thinking about using a heat pump to recoup the heat from outgoing shower water. The outgoing water is about 35 degrees centigrade and incoming in winter about 10 degrees. At 6 litres a minute the amount of heat that would need moving is some 12.5 kW, back to the original 10 degrees. For me there are 2 options, either a compressor heat pump or Peltier cells. Of course Peltiers are known for their low efficiency, but with no moving parts, low cost and small size very practical. Of course the question is, am I better off re-purposing an old dehumidifier/AC unit or going for the Peltier units. What kind of COP can I be expecting to achieve with either of the methods and is it worth starting this ?