In message ews.net,
Doctor Drivel writes

With a largish river 20m away I'm more inclined to a heat pump.

I don't know if o/p temperatures would be high enough for under floor
heating but I will bear it in mind for any future change of use.

A water sourced heat pump extracting from a moving stream or river is
by far the best system.

So what exit temperature could I expect from the heat exchanger and is
this high enough for under floor space heating?

There is also the issue of Environment Agency consent. I have not
investigated their views on this particular river (the Lea) but know
they normally expect a licence/payment to abstract and return water.

It may be acceptable to draw from a shallow well and return via a soak
at some distance.

regards


--
Tim Lamb