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re: problems with humidity
6 dec 2000
k3 wrote:
>our basement is nice and dry this time of year. come spring we'll have a
>little bit of water rise up thru the small cracks in the floor...
have you measured the humidity of the air in the basement at this time
of year, vs the amount of water on the floor? you mentioned that your
house was too humid when running the oil burner or woodstove in the
basement, and too dry when running the woodstove upstairs...
to help find where moisture is coming from, you might compare rhs at the
same air temperature, or measure them at different temps and then adjust
them. if you measure r1 (as a fraction vs %) at t1 (f) and r2 at t2, and
9621/(t1+460)-ln(r1) < 9621/(t2+460)-ln(r2), the air in the first case
contains more absolute moisture than the air in the second. for instance,
if r1 is 80% and t1 is 50 f in the basement and r2 is 60% and t2 is 70 f
upstairs, 9621/(50+460)-ln(0.8)=19.088 > 18.66=9621/(70+460)-ln(0.6), so
the basement air contains less moisture.
you could also measure the dew points directly by looking for condensation
on the outside of a glass of water with a few ice cubes as it cools while
you stir it with a thermometer. air containing more moisture (ie a higher
dew point) will condense on a glass containing warmer water.
maybe the basement is always dampish, even though you only see water
in the spring, and the humid air stays downstairs when there's no heat
source in the basement to better evaporate basement water and make the
warm humid basement air rise up to the first floor.
nick
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