Actually, there was no counterweight on the damper. Was it just not tuned yet? Or was there some other reason? I ask because mine is all screwed up an I cannot find a decent HVAC tech that knows how to tune a damper.
I have an oil burning hot water heater and furnace sharing the same metal chimney. each have their own barometric damper like the one above. Watching the hot water heater run.. I see its damper rock back and forth.. when the burner goes out, the damper rocks closed. When the furnace is running.. it's damper doesn't really move, but it does move the water heaters damper instead. when the furnace burner goes shuts off.. both the furnace damper and the water heater damper fly WIDE open for a second and close. What would cause that kind of sudden draw when the burner goes out. Is something wrong? because the water heater doesn't do that and they're connected to the same chimney pipe. Chimney has been swept within a year and both burners cleaned and nozzles changed at the beginning of this heating season.
