Kenneth wrote:
On Wed, 08 Oct 2008 08:43:01 -0500, dpb
wrote:

Kenneth wrote:
...
Consider the analogy (though far more extreme) to a clothes
drier:
...
It seems to me that over time (and let's remember that the
volume of air in the window is extremely low) both the RH,
and the absolute humidity of the air in the window would
drop.

Then, when the epoxy seals the hole (while the window is
still warm) the AH within would be lower than the
surrounding environment thus lowering the temperature at
which condensation would be visible.
...
Not unless the replacement air is drier than the air which one is trying
to displace -- which it isn't since it would be only some very small
fraction of air displaced by the volume expansion of a minimal amount of
(localized) heating.

The only way to make any significant difference would be the same way
the window was manufactured--draw a vacuum and fill w/ dry gas which
ain't gonna' happen.

Only real choice is to get the window repaired/replaced.

Hello again,

A replacement may, indeed, be the way to go, but...

I am also eager to understand the situation:

You say "not unless the replacement air is drier."

What replacement air?

As I described, it seems to me that as the heater air
expands, and exits through the bb hole, it takes with it
some water vapor. That makes it "drier" than it was.
Assuming that the epoxy is a seal, would that not decrease
the likelihood of condensation?

"What replacement air?"

Precisely...the air that leaves is simply a small fraction of the same
air that's already there. It doesn't "take" any disproportionate amount
of water vapor with it, only it's entrained share. Hence, the remaining
air (a _very_ tiny fraction less volume, perhaps) is still the same
moisture level.

Only unless you can get some mechanism to preferentially remove moisture
and/or replace the existing air w/ substantially drier air will it make
any difference. Either of those is pretty difficult to do w/o vacuum
pump and a source of dry gas, neither of which is likely to be handy.

--