Use heat pump to "heat" a heat pump?

wrf12345

Quiet on here so thought I would ask a silly question, if you can get three times (or more) of the energy out than you put in, does it not make sense to pre-heat the air drawn in with another heat pump. which might give a COP of nine or more? I realise UK cost would be mind-boggling but heat pumps themselves are actually quite cheap via China and not beyond the means of possibility to design a heat pumps with doubled up units.

On-the-coast

This won’t work for various reasons 2 of which are
- Heat pumps work over a fairly limited temperature differential making the preheating pointless. 
- the two units would interfere with each other. In essence think about putting a fridge inside a fridge…

Reed_Richards

The reason I can think of that it doesn't work is that fundamentally the efficiency depends on the temperature difference between the cold end and the hot end.  A two-stage heat pump (which this would be) isn't going to be any more efficient than a single stage heat pump.    

FreeBear

Reed_Richards said:

The reason I can think of that it doesn't work is that fundamentally the efficiency depends on the temperature difference between the cold end and the hot end.  A two-stage heat pump (which this would be) isn't going to be any more efficient than a single stage heat pump.    

And on top of that, you'll have two lots of electrical losses. So overall efficiency is likely to be much lower.