I have a problem. We have a whole house fan that we use this time of year
to cool the house. Last year we replace our gas water heater with a newer
model. Since then, I have learned the hard way that if there are not enough
windows open for the fan setting the fan will suck air down the chimney and
back through the water heater, blowing out the gas pilot in passing.
Currently, there are no dampers or anything in the vent stack. Would it
work to put one of those open when heated dampers in the vent stack to keep
the fan from blowing the pilot out?

I plan on checking the local ords as well, but would like to get some
opinions from the group as well.

Thanks in advance

Tim