On Fri, 17 Mar 2006 19:22:02 +0000 Andy Hall wrote :
Possibly, but unless you had a long length of it, you wouldn't get
the surface area needed to achieve the transfer. Think about heat
exchangers inside boilers and also plate heat exchangers for heating
water. These have huge surface areas by comparison.

I assume that what is envisaged is an insulated doughnut containing
combi pre-heat water with a length of ss flue passing though the middle
so that the heat from the flue pre-heats the water. A key problem ISTM
is that when the boiler stops you have this doughnut of warm water but
if you don't make use of it pretty quickly it will lose heat back into
the flue to the outside cold air. Likewise on one of those spring or
autumn days that is nice and mild but cold at night this heat exchanger
will turn into a pre-cooler.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
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