In message , tony sayer
writes
No they don't!. The one we have is fine except when it gets down to say
less than 2-3 deg c when it spends a lot of time defrosting itself
which means that its taking quite a bit off the mains in order to so
that, but anything above those temps, its fine.

If you could imagine its working in reverse to what its doing in the
summer months.. its trying to "cool" the outside air and get rid of the
heat inside the room!...

But where heat pumps really do work for heating is where there's a
modestly accessible geothermal source. This could be a bit of pipe laid
at a modest depth under the garden or a heat extractor in a local
stream.

Not particularly easy DIY projects though.

--
Clive Mitchell
http://www.bigclive.com