I have a double-pane window, downstairs on one end of the family room. It's
not very visible, being under the rear deck. Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. I'm looking
for advice on how to seal that up. I googled around, but surprisingly not
a lot there. Lots of articles on repairing broken windows or holes in
screens, but not this. Could not find anything on Amazon or on the sites of
Lowes or Home Depot. Any suggestions?

Thanks in Advance

"Glen Moffitt" wrote in message
...
I have a double-pane window, downstairs on one end of the family room. It's
not very visible, being under the rear deck. Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. I'm looking
for advice on how to seal that up. I googled around, but surprisingly not
a lot there. Lots of articles on repairing broken windows or holes in
screens, but not this. Could not find anything on Amazon or on the sites of
Lowes or Home Depot. Any suggestions?


You can epoxy over the hole, but it will show, and the seal is blown, so the
glass will fog up over time, I would expect.

"Glen Moffitt" wrote in message
...
I have a double-pane window, downstairs on one end of the family room.
It's
not very visible, being under the rear deck. Someone recently shot a
small
hole, probably with a BB gun, which penetrated the outer pane. I'm
looking
for advice on how to seal that up. I googled around, but surprisingly
not
a lot there. Lots of articles on repairing broken windows or holes in
screens, but not this. Could not find anything on Amazon or on the sites
of
Lowes or Home Depot. Any suggestions?

Thanks in Advance


You can always get one of these for $900
http://www.deltakits.com/windshield-...ts/products/3/

Holes can be filled with resin, but I have no idea how well it works. Maybe
a local glass place will have what you need.

If appearance is not critical, I'd use epoxy.

Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. I'm
looking
for advice on how to seal that up.

You could patch the hole with clear epoxy, however, since the outside air
has got inside, the moisture in the air inside (unless you re in the desert)
WILL tend to condense onto the glass from time to time depending on
temperature.

On Tue, 07 Oct 2008 18:29:55 -0700, Glen Moffitt
wrote:

I have a double-pane window, downstairs on one end of the family room. It's
not very visible, being under the rear deck. Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. I'm looking
for advice on how to seal that up. I googled around, but surprisingly not
a lot there. Lots of articles on repairing broken windows or holes in
screens, but not this. Could not find anything on Amazon or on the sites of
Lowes or Home Depot. Any suggestions?

Thanks in Advance

Their ideas are good. Don't push it in much or it will run down or
reach the other pane, which won't look as good.

You could also use clear silicone cement like from GE. They might
have that in a hardware store but will definitely have it in a good
autoparts store.

On Tue, 07 Oct 2008 18:29:55 -0700, Glen Moffitt
wrote:

I have a double-pane window, downstairs on one end of the family room. It's
not very visible, being under the rear deck. Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. I'm looking
for advice on how to seal that up. I googled around, but surprisingly not
a lot there. Lots of articles on repairing broken windows or holes in
screens, but not this. Could not find anything on Amazon or on the sites of
Lowes or Home Depot. Any suggestions?

Thanks in Advance

Howdy,

You have seen good ideas about epoxy, and I suspect the
concerns you have seen about the humidity of the air that
entered are correct.

But, you might be able to mitigate the condensation problems
if you were to heat the window some before applying the
epoxy.

I might try aiming some sort of space heater at the glass
for a while before doing the repair.

Even heating it slightly would lower the level of humidity
between the panes, and that would, in turn, lower the
temperature at which you would see condensation.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

"Kenneth" wrote in message
...

I might try aiming some sort of space heater at the glass
for a while before doing the repair.

Even heating it slightly would lower the level of humidity
between the panes, and that would, in turn, lower the
temperature at which you would see condensation.

The heat won't remove the moisture in the trapped air, only make it warmer.
The moisture would have to escape thru the hole, which won't happen.

Glen Moffitt wrote:
I have a double-pane window, downstairs on one end of the family room. It's
not very visible, being under the rear deck. Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. I'm looking
for advice on how to seal that up. I googled around, but surprisingly not
a lot there. Lots of articles on repairing broken windows or holes in
screens, but not this. Could not find anything on Amazon or on the sites of
Lowes or Home Depot. Any suggestions?

Thanks in Advance

Hi,
I'd just have the glass parts replaced. Seal is broken and it's no good
insulator and it'll fog up when raining or weather gets cold.

On Oct 7, 8:29*pm, Glen Moffitt wrote:
I have a double-pane window, downstairs on one end of the family room. *It's
not very visible, being under the rear deck. *Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. *I'm looking
for advice on how to seal that up. * I googled around, but surprisingly not
a lot there. *Lots of articles on repairing broken windows or holes in
screens, but not this. *Could not find anything on Amazon or on the sites of
Lowes or Home Depot. *Any suggestions?

Thanks in Advance

It will eventualy fog so you cant see out of it, if its big you may
think insurance. You can seal it with a bit of caulk

Rudy wrote:
Someone recently shot a small hole, probably with a BB gun, which
penetrated the outer pane...

You could patch the hole with clear epoxy, however, since the outside air
has got inside, the moisture in the air inside (unless you re in the desert)
WILL tend to condense onto the glass from time to time...

Perhaps we can dry that air. Before plugging the BB hole, we might drill
a hole in the glass seal with a tube to an aquarium air pump in a box
with a few Tyvek bags filled with desiccant clay...

http://www.uline.com/ProductDetail.a...-1606&ref=1006

Nick

Kenneth wrote:

I might try aiming some sort of space heater at the glass
for a while before doing the repair.

Even heating it slightly would lower the level of humidity
between the panes, and that would, in turn, lower the
temperature at which you would see condensation.

Heating air lowers the RH but doesn't change the absolute moisture content,
so the air would have the same dew point after it cooled.

We might dry the air by running a tube from a dessicant box to the hole
and cycling the space heater every half hour for a few hours to pump air
out and back into the window cavity.

Nick

On Oct 7, 9:29*pm, Glen Moffitt wrote:
I have a double-pane window, downstairs on one end of the family room. *It's
not very visible, being under the rear deck. *Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. *I'm looking
for advice on how to seal that up. * I googled around, but surprisingly not
a lot there. *Lots of articles on repairing broken windows or holes in
screens, but not this. *Could not find anything on Amazon or on the sites of
Lowes or Home Depot. *Any suggestions?

Thanks in Advance

Two approaches.

Replace the double-pane glass. If it's an Andersen they're readily
available and not too horrendously priced for a replacement part.

Low-tech, low-cost, under the deck not very visible repair - clear
plastic packing tape. It'll be clearer and less obtrusive than any
caulk or epoxy repair you can make and you'll have no trouble
controlling the depth of the repair. I'd first let the hole sit for a
while to make sure that any cracks won't propagate. Then I'd use some
silica gel packets (typically found in shoe boxes and electronics
packaging) to dry out the air inside the insulated glass unit. Dry
the packets in the oven at low temperature for a while, then put the
silica packet over the hole and tape plastic over the packet so it
will only absorb moisture from inside the hole. Let it sit for a
while, then replace the packet with a freshly dried one (quickly!).
It should only take a couple or three packets as they're can't be that
much moisture inside. Then remove the silica packet and quickly tape
over the hole. The edges of the tape are usually what's visible due
to handling and ragged edges from cutting it, so you could use an
razor knife to cut the tape edges off after it's been burnished down
on the glass (don't press too hard). A major benefit is that it's
easy to redo the poor-man's dessicant technique if moisture appears
between the panes during the winter.

R

On 8 Oct 2008 06:48:04 -0400,
wrote:

Kenneth wrote:

I might try aiming some sort of space heater at the glass
for a while before doing the repair.

Even heating it slightly would lower the level of humidity
between the panes, and that would, in turn, lower the
temperature at which you would see condensation.

Heating air lowers the RH but doesn't change the absolute moisture content,
so the air would have the same dew point after it cooled.

We might dry the air by running a tube from a dessicant box to the hole
and cycling the space heater every half hour for a few hours to pump air
out and back into the window cavity.

Nick

Hi Nick,

No Physicist I, but at first, I thought, "Of course... He's
absolutely right."

Then, on further reflection, (though I certainly may be
wrong) I came to see it differently:

The window used to be a closed vessel (and were that to
continue, your comment would, I believe, be correct.)

But now, it is an open vessel (the bb hole.)

Consider the analogy (though far more extreme) to a clothes
drier:

It heats the air in the drum, the RH goes down, the water in
the clothes is drawn to the air, and that moist air (with
the water it carries) is expelled by a fan via the duct.

It would appear to me that much the same thing would happen
in the case of the window:

A space heater (or some such) heats the glass of the window,
and after a few minutes, heats the air enclosed. As that air
warms, at least two things happen. First, as you say, its RH
drops. But in addition to that, it expands, expelling some
of that air via the bb hole, and with it, the moisture it
carries.

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.

Might I have that right?

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

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.

--

Why not just break open a few of those dessicant packets and push the
pellets through the hole into the window cavity? They'll trap the
moisture and hold it.

You'll NEVER get the moisture out by taping dessicant packets over the
hole.

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?

Thanks,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Oct 8, 8:32*am, RicodJour wrote:
On Oct 7, 9:29*pm, Glen Moffitt wrote:

I have a double-pane window, downstairs on one end of the family room. *It's
not very visible, being under the rear deck. *Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. *I'm looking
for advice on how to seal that up. * I googled around, but surprisingly not
a lot there. *Lots of articles on repairing broken windows or holes in
screens, but not this. *Could not find anything on Amazon or on the sites of
Lowes or Home Depot. *Any suggestions?

Thanks in Advance

Two approaches.

Replace the double-pane glass. *If it's an Andersen they're readily
available and not too horrendously priced for a replacement part.

Low-tech, low-cost, under the deck not very visible repair - clear
plastic packing tape. *It'll be clearer and less obtrusive than any
caulk or epoxy repair you can make and you'll have no trouble
controlling the depth of the repair. *I'd first let the hole sit for a
while to make sure that any cracks won't propagate. *Then I'd use some
silica gel packets (typically found in shoe boxes and electronics
packaging) to dry out the air inside the insulated glass unit. *Dry
the packets in the oven at low temperature for a while, then put the
silica packet over the hole and tape plastic over the packet so it
will only absorb moisture from inside the hole. *Let it sit for a
while, then replace the packet with a freshly dried one (quickly!).
It should only take a couple or three packets as they're can't be that
much moisture inside. *Then remove the silica packet and quickly tape
over the hole. *The edges of the tape are usually what's visible due
to handling and ragged edges from cutting it, so you could use an
razor knife to cut the tape edges off after it's been burnished down
on the glass (don't press too hard). *A major benefit is that it's
easy to redo the poor-man's dessicant technique if moisture appears
between the panes during the winter.

R

My neighbor's boy friend's kids shot mine, it cost about $60USD for a
replacement. I took the old sash into the shop and they replaced the
glass. This took two trips to the shop. Once for them to measure the
glass so they could order the replacement glass and then go back for
them to put the glass in the sash.

Jimmie

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.

--

On Oct 8, 8:32*am, RicodJour wrote:
On Oct 7, 9:29*pm, Glen Moffitt wrote:

I have a double-pane window, downstairs on one end of the family room. *It's
not very visible, being under the rear deck. *Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. *I'm looking
for advice on how to seal that up. * I googled around, but surprisingly not
a lot there. *Lots of articles on repairing broken windows or holes in
screens, but not this. *Could not find anything on Amazon or on the sites of
Lowes or Home Depot. *Any suggestions?

Thanks in Advance

Two approaches.

Replace the double-pane glass. *If it's an Andersen they're readily
available and not too horrendously priced for a replacement part.

Low-tech, low-cost, under the deck not very visible repair - clear
plastic packing tape. *It'll be clearer and less obtrusive than any
caulk or epoxy repair you can make and you'll have no trouble
controlling the depth of the repair. *I'd first let the hole sit for a
while to make sure that any cracks won't propagate. *Then I'd use some
silica gel packets (typically found in shoe boxes and electronics
packaging) to dry out the air inside the insulated glass unit. *Dry
the packets in the oven at low temperature for a while, then put the
silica packet over the hole and tape plastic over the packet so it
will only absorb moisture from inside the hole. *Let it sit for a
while, then replace the packet with a freshly dried one (quickly!).
It should only take a couple or three packets as they're can't be that
much moisture inside. *Then remove the silica packet and quickly tape
over the hole. *The edges of the tape are usually what's visible due
to handling and ragged edges from cutting it, so you could use an
razor knife to cut the tape edges off after it's been burnished down
on the glass (don't press too hard). *A major benefit is that it's
easy to redo the poor-man's dessicant technique if moisture appears
between the panes during the winter.

R

Third option: This is only theoretical, but it would work as well as
the others. Drill a second hole for air to escape. Go to your local,
upscale wine shoppe and get a can of the stuff that they use to squirt
into opened wine bottles so that you can re-cork them and put then in
the refrigerator for a while and not have them go bad. It's mostly
(totally?) nitrogen, I would guess. You could then refill the window
with gas and reseal the holes.

PanHandler wrote:
"Kenneth" wrote in message
...


I might try aiming some sort of space heater at the glass
for a while before doing the repair.

Even heating it slightly would lower the level of humidity
between the panes, and that would, in turn, lower the
temperature at which you would see condensation.


The heat won't remove the moisture in the trapped air, only make it warmer.
The moisture would have to escape thru the hole, which won't happen.



Anyone tried these guys or similar services which say they drill a hole
in the outer pane and put in a one way valve as part of their process?

http://www.defogit.com/

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

dpb wrote:
....
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.
....
That, of course, is mass, not volume--the volume is fixed only the
density decreases slightly owing to the postulated heating...

--

The way that we used to get moisture out of small inaccessible areas (like a
bellows) was to pull a vacuum (which would evaporate the moisture)and
basically suck it out. Not a practical solution for this problem but just
wanted to add a tidbit on how something like this is handled.
MLD
wrote in message
...
Kenneth wrote:

I might try aiming some sort of space heater at the glass
for a while before doing the repair.

Even heating it slightly would lower the level of humidity
between the panes, and that would, in turn, lower the
temperature at which you would see condensation.

Heating air lowers the RH but doesn't change the absolute moisture
content,
so the air would have the same dew point after it cooled.

We might dry the air by running a tube from a dessicant box to the hole
and cycling the space heater every half hour for a few hours to pump air
out and back into the window cavity.

Nick

On Oct 8, 10:37*am, "MLD" wrote:
The way that we used to get moisture out of small inaccessible areas (like a
bellows) was to pull a vacuum (which would evaporate the moisture)and
basically suck it out. *Not a practical solution for this problem but just
wanted to add a tidbit on how something like this is handled.
wrote in message



Actually, I think he should draw a vacuum on his window. At about 14
psi, it'll completely destroy the glass and he'll have to replace the
window, which is the right "fix" anyway.

On Oct 8, 10:56*am, Jeff Wisnia wrote:
PanHandler wrote:
"Kenneth" wrote in message
.. .

I might try aiming some sort of space heater at the glass
for a while before doing the repair.

Even heating it slightly would lower the level of humidity
between the panes, and that would, in turn, lower the
temperature at which you would see condensation.

The heat won't remove the moisture in the trapped air, only make it warmer.
The moisture would have to escape thru the hole, which won't happen.

Anyone tried these guys or similar services which say they drill a hole
in the outer pane and put in a one way valve as part of their process?

http://www.defogit.com/

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.- Hide quoted text -

- Show quoted text -

Dont know nothing about thme but there ad is pure BS. If you have fog
in your window the window either leaks or it was not properly prepared
when it was made.

Jimmie

Thanks everyone for all the suggestions. I'll probably put a temporary seal
on it and then replace it later. Most of the time I'm near it, it's
nighttime and I have the blinds down anyway.

Thanks again


On 10/8/08 5:32 AM, in article
,
"RicodJour" wrote:

On Oct 7, 9:29*pm, Glen Moffitt wrote:
I have a double-pane window, downstairs on one end of the family room. *It's
not very visible, being under the rear deck. *Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. *I'm looking
for advice on how to seal that up. * I googled around, but surprisingly not
a lot there. *Lots of articles on repairing broken windows or holes in
screens, but not this. *Could not find anything on Amazon or on the sites of
Lowes or Home Depot. *Any suggestions?

Thanks in Advance

Two approaches.

Replace the double-pane glass. If it's an Andersen they're readily
available and not too horrendously priced for a replacement part.

Low-tech, low-cost, under the deck not very visible repair - clear
plastic packing tape. It'll be clearer and less obtrusive than any
caulk or epoxy repair you can make and you'll have no trouble
controlling the depth of the repair. I'd first let the hole sit for a
while to make sure that any cracks won't propagate. Then I'd use some
silica gel packets (typically found in shoe boxes and electronics
packaging) to dry out the air inside the insulated glass unit. Dry
the packets in the oven at low temperature for a while, then put the
silica packet over the hole and tape plastic over the packet so it
will only absorb moisture from inside the hole. Let it sit for a
while, then replace the packet with a freshly dried one (quickly!).
It should only take a couple or three packets as they're can't be that
much moisture inside. Then remove the silica packet and quickly tape
over the hole. The edges of the tape are usually what's visible due
to handling and ragged edges from cutting it, so you could use an
razor knife to cut the tape edges off after it's been burnished down
on the glass (don't press too hard). A major benefit is that it's
easy to redo the poor-man's dessicant technique if moisture appears
between the panes during the winter.

R

Glen Moffitt writes:

I have a double-pane window, downstairs on one end of the family room. It's
not very visible, being under the rear deck. Someone recently shot a small
hole, probably with a BB gun, which penetrated the outer pane. I'm looking
for advice on how to seal that up. I googled around, but surprisingly not
a lot there. Lots of articles on repairing broken windows or holes in
screens, but not this. Could not find anything on Amazon or on the sites of
Lowes or Home Depot. Any suggestions?

Some of these windows have lifetime guarantees.
Not sure about a BB gun, but it could be worth looking into.

I had a thermal window crack and they sent me replacement
panes, no questions asked.

Your window is most likely Argon filled.
Without the Argon, the window will be 6% less efficient:

http://www.weathermaster-window.com/glass.html

I don't think there is anything practical you can do about the
condensation you will see inside the window.

"Kenneth" wrote in message
Consider the analogy (though far more extreme) to a clothes
drier:

It heats the air in the drum, the RH goes down, the water in
the clothes is drawn to the air, and that moist air (with
the water it carries) is expelled by a fan via the duct.

It would appear to me that much the same thing would happen
in the case of the window:

So how long should he run the dryer with the window in it? I'd recommend
the permanent press cycle.

dpb wrote:

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.

It seems to me that drawing a vacuum could implode the window.

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

Or dry the air in the cavity.

Nick

dpb wrote:

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.

Gee, how could we that? :-)

Either of those is pretty difficult to do w/o vacuum pump and a source
of dry gas...

I disagree.

Nick

dpb wrote:

... the air that leaves is simply a small fraction of the same air that's
already there.

Heating the window from 70 to 100 F at constant pressure increases the air
volume by (460+100)/(460+70) = 1.057, ie 5.7% no? How many times must we
heat the window to lower the cavity air dew point to 0 F, if it starts at
50% RH and we replace the air that leaves the hole with dry air?

Nick

MLD wrote:

The way that we used to get moisture out of small inaccessible areas (like
a bellows) was to pull a vacuum (which would evaporate the moisture) and
basically suck it out. Not a practical solution for this problem...

How about a repetitive partial vacuum and a source of dry air, eg a box full
of desiccant bags? How many times do we have to squeeze a bellows to remove
5% of the air from a window cavity, with a check valve and a vacuum breaker
that allow dry air to replace expelled air when the bellows is released, if
we want to lower the cavity dew point from 50 to 10 F?

Nick

... How many times do we have to squeeze a bellows to remove 5% of the air
from a window cavity, with a check valve and a vacuum breaker that allow
dry air to replace withdrawn air when the bellows is released, if we want
to lower the cavity dew point from 50 to 10 F?

.... 31 times.

10 P=.5*EXP(17.863-9621/(460+70))'initial cavity vapor pressure ("Hg)
20 W=.62198/(29.921/P-1)'initial humidity ratio (#w/#a)
30 PRINT P,W
40 P10=EXP(17.863-9621/(460+10))'vapor pressure at 10 F and 100% RH
50 W10=.62198/(29.921/P10-1)'10 F humidity ratio
60 W=.95*W'squeeze bellows
70 IF WW10 THEN N=N+1:GOTO 60
80 PRINT N,W,W10

..3741957 7.87707E-03

31 1.525878E-03 1.536647E-03

Nick

wrote:
dpb wrote:

... the air that leaves is simply a small fraction of the same air that's
already there.

Heating the window from 70 to 100 F at constant pressure increases the air
volume by (460+100)/(460+70) = 1.057, ie 5.7% no? How many times must we
heat the window to lower the cavity air dew point to 0 F, if it starts at
50% RH and we replace the air that leaves the hole with dry air?

A bunch unless you can somehow figure out which new dry air is different
from the existing on the subsequent heating cycles.

Just go get the window fixed...

--

wrote:
dpb wrote:

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.

Gee, how could we that? :-)

Either of those is pretty difficult to do w/o vacuum pump and a source
of dry gas...

I disagree.

So what's your plan? The heating route certainly isn't very effective.

--

wrote:
... How many times do we have to squeeze a bellows to remove 5% of the air
from a window cavity, with a check valve and a vacuum breaker that allow
dry air to replace withdrawn air when the bellows is released, if we want
to lower the cavity dew point from 50 to 10 F?

... 31 times.
....
Didn't read the code but that's "simple" fix anybody is just going to
have the facilities to do just lying around--right!

At first blush it appears assumed totally dry air which wouldn't be
likely and doesn't account for mixing so that part of the introduced air
will be withdrawn as well as the initial on every cycle.

--

dpb wrote:

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.

I believe they put desiccant in the separator channels. The air that is
sealed in does not have to be absolutely dry.

Otherwise I agree with your comments.


The air in the window will equalize with the outside air. The hole could
be sealed when the dew point of the outside air is sufficiently low
(below the lowest temperature in winter).

--
bud--

dpb wrote:
wrote:
... How many times do we have to squeeze a bellows to remove 5% of the air
from a window cavity, with a check valve and a vacuum breaker that allow
dry air to replace withdrawn air when the bellows is released, if we want
to lower the cavity dew point from 50 to 10 F?

... 31 times.
...
Didn't read the code but that's "simple" fix anybody is just going to
have the facilities to do just lying around--right!

The parts might cost $25.

At first blush it appears assumed totally dry air which wouldn't be likely

Air from a plastic box with a few desiccant bags would be close.

and doesn't account for mixing so that part of the introduced air
will be withdrawn as well as the initial on every cycle.

But it does. Read the code... a lot of 3rd graders used to speak BASIC :-)

10 P=.5*EXP(17.863-9621/(460+70))'initial cavity vapor pressure ("Hg)
20 W=.62198/(29.921/P-1)'initial humidity ratio (#w/#a)
30 PRINT P,W
40 P10=EXP(17.863-9621/(460+10))'vapor pressure at 10 F and 100% RH
50 W10=.62198/(29.921/P10-1)'10 F humidity ratio
60 W=.95*W'squeeze bellows
70 IF WW10 THEN N=N+1:GOTO 60
80 PRINT N,W,W10

..3741957 7.87707E-03

31 1.525878E-03 1.536647E-03

Nick

wrote:
....
The parts might cost $25.
....
And futzing around for several hours w/ the end result being a partially
evacuated window w/ an obvious hole in the middle that undoubtedly won't
be a permanent repair...

Meanwhile, $50 or so will put it back to new condition and depending on
insurance might conceivably even have some fraction covered.

While an interesting intellectual exercise, just isn't the logical
solution unless one is simply into doing stuff like that for the fun of it.

--

dpb wrote:

wrote:

The parts might cost $25.

Maybe less, for an aquarium pump and a timer and a little tubing and
a plastic box and a few desiccant bags.

And futzing around for several hours...

Maybe a half-hour :-)

w/ the end result being a partially evacuated window

Not, when it's over.

w/ an obvious hole in the middle...

Not, with an indexed-matched clear epoxy.

Meanwhile, $50 or so will put it back to new condition and depending on
insurance might conceivably even have some fraction covered.

I just spent $230 for the glass and a few hours labor to replace
a fogged sliding glass door panel.

10 P=.5*EXP(17.863-9621/(460+70))'initial cavity vapor pressure ("Hg)
20 W=.62198/(29.921/P-1)'initial humidity ratio (#w/#a)
30 PRINT P,W
40 P10=EXP(17.863-9621/(460+10))'vapor pressure at 10 F and 100% RH
50 W10=.62198/(29.921/P10-1)'10 F humidity ratio
60 W=.95*W'squeeze bellows
70 IF WW10 THEN N=N+1:GOTO 60
80 PRINT N,W,W10

..3741957 7.87707E-03

31 1.525878E-03 1.536647E-03

^
--- this woulda been 1/0.05 = 20 if there were no air mixing.

Nick

wrote:
....
I just spent $230 for the glass and a few hours labor to replace
a fogged sliding glass door panel.
....
And I had a double-pane single-lite window done last year for about $50
-- far more nearly what the OP was speaking of.

Since glass is covered under my homeowners at replacement for hail
damage, it was nothing out of pocket.

Again, if you're into futzing around w/ stuff, so be it; in general I've
more productive/interesting things to do...

--