The message
from "David Hill" contains these
words:

"..........You can make a heat pump for no cost at all, or very little -
assuming you can find someone with an old freezer they don't want ......."

Will a fridge do?

Yes, but you won't get a lot of heat concentrated from so small a
compressor. To do a decent job you really need an old commercial unit,
but a big domestic one would be reasonably effective.

--
Rusty
Open the creaking gate to make a horrid.squeak, then lower the foobar.
http://www.users.zetnet.co.uk/hi-fi/