Saw a thing on one of those DIY shows that was an air bladder that blocked the
flue when stuffed in and pumped up.








On Sun, 1 Jun 2008 18:09:56 +0000 (UTC), Jonathan Grobe
wrote:

I have a traditional brick chimney which I no longer
use as I have switched to a high efficiency propane
furnace (so the smoke goes out through a small pipe).

Any estimates of how much heat loss I am having
(brick having a low R-value) and what I should about
it? (I don't think I have the energy to remove it).