Our basement is a little damp, and doesn't have very good ventilation.
It's a finished, carpeted basement, in good condition -- just damp (it
rains a lot here). A dehumidifier would do the job, but I've read that
they're expensive to run. We rent, so I don't want to invest a lot of
money in anything permanent. Any frugal suggestions for how to dry a
Airseal it well, then add a humidistat and a fan to move at least 200 cfm
of air from the basement floor upstairs whenever the RH near the floor is
more than 60%. This requires some sort of airshaft, eg a laundry chute or
an enclosed stairwell with a door at the bottom with a vent in the lower
part of the door. It also requires a return airpath, eg a floor grate.
Herbach and Rademan (800) 848-8001 http://www.herbach.com sell a nice
$4.95 Navy surplus humidistat, their item number TM89HVC5203, with a
20-80% range, a 3-6% differential, and a 7.5A 125V switch that can be
wired to open or close on humidity rise.
The problem is that the cool humid air comes from the warmer atmospheric air
outside that cools (due to the basement being in ground), and thus the
relative humidity increases as the temperature decreases. If you draw all
the air out, it will again be replaced by outside air, that will just cool
again and the RH will climb.
I know some people that have tried venting a humid basement, and it just
makes the problem worse.
How would you check whether you have sealed the house too well?
An airtight house is a recipe for sick building syndrome.
Unless they like to design such systems as a science project or hobby,
it's more effective for the average person to just fix the problem
by using a dehumidifier.
That's extremely hard to do, in practice, akin to turning your house
into a boat. The RH would climb to 100% with condensation on windows
inside a completely airtight house.
Nonono. You are completely wrong. It's a recipe for a happier healthier
building and occupants with lower energy bills, according to one Canadian
R2000 home study. These homes have "mechanical ventilation systems," eg
humidistats that turn on small exhaust fans. The R2000 standard does not
require ERVs or HRVs.
Nonono. You are completely wrong. Witness soaring Humidex sales, in spite
of their $1K price tag and less-efficient outdoor exhaust. I installed a
basement-floor-to-upstairs circulator in a house yesterday, in about 20
minutes, using a $4.95 humidistat and a $12 window box fan.
I am in Alberta where the humidity is fairy dry. I got rid of the
furnace humidifier as it grows a slimy mold that gets blown through
the ducts and throughout the house. I don't have a dampness problem.
That said, the Canadian HVAC code requires a fresh air intake 8 inch
duct from the outside that is directly connected to the air return
trunk to the furnace. There is also a separate 8 " combustion air
air duct that opens near the furnace burners. Therefore the idea of
is impossible and superfluous. If you have a furnace system similar
Canadian code set up perhaps the best way is to run the fan in the
furnace to circulate the air and equalize the humidity with the
I don't have any air conditioning so I don't know what a damp basement
in an AC cooled situation will need.
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