On Thu, 22 Dec 2005 19:29:38 -0800, daniel peterman wrote:
I've been using my fireplace latley just to take the chill off and I
know about 75% 0f the heat is just going up the chimney.
Part of the main double walled stack is exposed near the raised ceiling
for abot 3 feet. Is there a safe way to tap into the galvanized stack
and install some sort of heat exchanger with a blower to improve
efficiency?

Well, yes, but. The cooler you make your chimney, the faster the
creosote will build up. So you can extract heat from the exhaust gas
(well, that's what it is) just by adding fins and a fan to the outside
of the galvanized chimney inside the house, but get it too cold and the
creosote will condense and stick, rather than go up and out. I'm sure
someone here can give you that temperature off the top of their heads,
otherwise google knows.