"Ray" wrote in message
news:TgYZi.303$WM.189@trndny05...
Our very old coop building has a fireplace in each of the six units. None has
been used for a good many years.

They all have dampers, but these clearly do not prevent heat-loss up the
chimney.

What's the best way to stop this heat loss? We would like to retain the option
of using the fireplaces in the future if tenants wish to do so.

I would guess that we might stuff some insulation bats of fiber glass or rock
wool in the openings. Does that make sense? If not, what does make sense?

You could put insulation, rags, waded up newspaper, packing peanuts, etc. into a
plastic bag. Fold or tie the top. Push it up against the damper with a plywood
board or even thick chunk of cardboard covering the bottom, and prop it in place
with a stick. The idea is to push the compressable mass over the whole damper
assembly to block leaks. Also, make sure rain can't get into top of the chimney.
with a cap of some sort.

Bob