Andy Hall wrote:
On Fri, 17 Mar 2006 11:14:30 -0000, "Tim Downie"
Maybe. I remain unconvinced.

I would look elsewhere first


Andy, I don't *know* if my idea would be viable but you seem to be taking
the position "It hasn't been done so it can't work" which may be right most
of the time but certainly not all of the time.

There's nothing logically wrong with my idea that you've pointed out. I see
no reason why a cheap co-axial flue extension shouldn't reclaim a
significant amount of waste heat. It doesn't need to be complicated and if
the bore diameters were reasonably dimensioned, it seems unlikely that it
would greatly increase the amount of backpressure over what a modern fan
flues boiler can cope with.

Tim