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GBlist: The air filter from hell



Bella et al,

Whenever I think of air filters in hvac systems I remember a house we
tested belonging to a family that had been "itching" for eighteen months
since they had moved in.

To solve their problem, their hvac man had installed an "electrostatic"
filter behind the return air grill, alledgedly to filter all the return
air. The return air passed through the filter into a chase (a building
cavity) which served as a duct of sorts to the air handler/furnace.

With the electrostatic filter removed, the negative pressure in this
chase/duct measured 12 Pascals with the air handler on. Reasonable.

When the filter went back in, it was VERY HARD for air to squeeze through
those little filter holes and, as the air handler starved and sucked harder
for air, the negative pressure in the chase jumped from 12 to 85 Pascals.
Now only some of the air was coming through the filter. The rest, bypassing
the filter, came from anywhere it could--that is, from anywhere that was
easier.

One depressurized connecting wall straddled and hid a hole knocked in the
slab for a washing machine drain, but which was now vigorously providing
soil gas through the wall cavity to the return and the house-- and not
ordinary soil gas, but soil gas enriched by the termiticides the ground was
poisoned with before the slab was poured and the chemicals sprayed and
sprinkled in the yard (which was now at negative pressure as well) to make
it green and free of weeds, bugs, ticks and fleas.

Not to be left out, the attic bypasses into the chase were whistling. But
you didn't need to hear them to find them; they were those little holes and
cracks in the middle of the bare spots on the attic floor--the rest of
which was deep in blown fiberglass insulation which was slowly dancing its
way towards that giant sucking sound.

I'll always remember that house.

Ron


Ron Hughes
THE WHOLE HOUSE
http://www.energyhome.com
P.O. Box 251416
Little Rock, AR 72225
501.666.4377 biz
501.666.8676 fax



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