Andy Champ wrote:
It occurs to me that the current condensing boilers rely on the low
temperature of the returned water flow to get their efficiency. Those
of us with old fashioned systems designed to run non-condensing have a
high return temp., so the boilers won't condense. But there's a nice
supply of cold air available to cool the exhaust further - which is the
intake. An intake-exhaust heat exchanger would surely recover at least
some of the waste heat in the exhaust. Not all of it, firstly because a
heat exchanger, even counter current, is never completely effective, and
second because the heat capacity of warm steamy air that's condensing is
far higher than that of dry, cool air - but it's worth a go, isn't it?

so waffle mode off, does anyone make such a beast? And is it any good?


THhey are called balanced flue boilers. I am sure there are one or two
out there ;-)


Andy