I read about a passive vent damper on homeenergy.org for a gas water heater
that is essentially a very light plate that rises to open the flue when the
heater fires up and settles down to close the flue when the heater stops.
Its non-electric, completely mechanical. Its supposed to cut standby losses
quite a bit. I've been unable to find one for sale. Anyone every see this?
Know where it could be purchased?