OK, here's a question with some science to back me up.
I have a leak in my a/c drain line. It happens to be right under the a/
c unit. Took a while to find the leak, and it turned out just to be a
cracked hose under the unit. Pretty strange. But that's not the
Now, before I located the leak, I was sopping up the mess with beach
towels. LOTS of water. When I found the leak, I put a pan under it,
and started emptying the pan every few hours. The amount of drain
water amazed me. It's pretty hot and humid outside in the daytime, and
my a/c runs ever two hours or so. When it does, I end up with about
of drain water each time it runs. Holy toledo! That's
coming out of the air in my house every two hours???
So I did a calculation, and found that in my house, with about 2000
square feet of HVAC space (with 8 foot ceilings), 50% humidity at 75F
means that there are about 19 cups of water total in the air in my
house. Again, holy toledo! So my a/c is pulling about a third of that
out every few hours. Now, I might expect my a/c to do that.
But wait a minute. That means that about 6 cups of water is entering
my house every few hours! Now, my house is very well sealed. Where are
those 6 cups of water coming from? If I don't open the exterior door,
how are those 6 cups getting in? I can't believe it's evaporation from
toilets, sink, etc., and I can't believe that I'm exhaling that
amount. So where is it coming from?
I'm on a slab. Is the slab permeable enough that water is soaking up
from underneath? I'm well above the water table, BTW. Is drywall
permeable to water, such that the humid exterior air that makes it
past my (substantial) blown-in insulation gets through into the house?
Now, I understand that when the temp/RH is 90F/60% outside, that air
holds twice as much water as my 75F/50% air inside. So it doesn't take
a lot of outside air getting in to bring lots of water in, but
I always think about a/c in terms of heat management, and thermal
insulation. But it's pretty interesting to think about water
management, and to what extent the inside of the home is insulated