[Greenbuilding] heating water with wood stove - heat transfer/efficiency calculations?

[Nick Pyner]

This is really outside my bailiwick but the matter came up in a ski lodge
where I have installed a grey water heat exchanger and, in-season, a fire is
running pretty well all day.

It occurred to me that the best solution was to have a 12m coil of 20mm soft
copper inside an uninsulated flue.

We are looking at doing this in time for the next season.


Nick Pyner

Dee Why   NSW

-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org]On Behalf Of
Frank Tettemer

 >> During the seventies, I tried 100 feet of soft copper, wrapped
around six inch single walled flue pipe, with the 40 gallon tank
positioned so that there was about ten feet total rise, from the lowest
portion to the highest portion in the closed loop.  With the stove
burning during mid winter, the water got warm only, not hot. we tried
wrapping the outer portion of the copper coil with fiberglass and
builder's aluminum foil, which helped. But it still wasn't great.