My house was built in 1920 in Providence, RI.
I'm not sure of the design of the entire chimney, but the water heater and furnace vent into the chimney. I am considering using a Chimney Balloon, but it would need to go above the damper since there's not a good surface to install it below the damper. Would it be likely that I'd block the ventilation of the water heater and furnace by installing the Chimney Balloon?