Forced Hot Air Adds
Water to Exterior Walls
To the Editor:
I'd like to add a couple of thoughts
to Stephen Smulski's excellent article
"Water in the Walls" (8/94). In Case
2, the humidifiers on the home's two
forced-hot-air systems are listed first
among a number of probable causes.
My own experience confirms this, and
suggests that even without a humidifier,
a forced-hot-air (FHA) system can
be the key factor driving moisture into
exterior walls.
It's common for FHA systems to
have undersized returns and/or large
return leaks in the basement, both of
which result in the house being pressurized.
This in turn drives airborne
moisture in the house into the walls
and ceilings.
To add insult to injury, in the