wrote in message
...
daestrom wrote:

Condensation can be seen as two possible problems. Either there is too
much
moisture in the air so the dew point is pretty high, or the inside
surfaces
of the glass/frame are so cold that they are below the dew point for even
relatively dry air.

With no moisture source in the house, indoor and outdoor air would have
the same dew point. Minimal moisture from human activities (about 2 gal
per day for a family of 4) wouldn't change this much, for an average US
(224 cfm) air-leaky house.


OTOH, most folks don't like the air that dry in the winter. Some of us
prefer the RH above 30% or so, on a day like today, warming up outside air
(dewpoint 20F) would mean just 14% RH. If the OP is seeing frost forming
occasionally, then the outside temperature must be going below 30F a fair
amount of time (warmed to 71F that's 21% RH).

And adding storm windows (even the plastic I mentioned) will help reduce
heat loss and drafts.

daestrom