I'm going to be replacing my single pane double hung windows with low
e double hung sash kits with new jambliners.There are storm windows
currently on the house.Is it ok to keep/use the storms with the low e
windows or will there be a problem with too much heat buildup or
reflection problem between the new sashes and the storms.
The reason I want to do this is so i can use the screens in the storm
windows in summer and then put the glass panels in for the winter.

From: maistomeadows

s it ok to keep/use the storms with the low e
windows or will there be a problem with too much heat buildup or
reflection problem between the new sashes and the storms.
The reason I want to do this is so i can use the screens in the storm
windows in summer and then put the glass panels in for the winter.


you will get very little benefit from the storm windows in the form of R
value...some wind resistance, but that is not a problem with new weather
stripping and sashes, especially double paned glass....the screen will be your
only benefit...if you don't want to invest in full screens for the windows
themselves(usualy mount with a couple slide pins) then you can leave the storm
frames in for the screens....if your new jambliners are vinyl(which likely they
are) you do NOT want to have the storm sashes closed..heat build up *is* a
major concern ,even in the winter time...heat from direct sunlight can build up
between the storm sashes and your window sashes very quickly even in the winter
time...the vinyl jambliners are prone to warp at about 150-160 degrees (F)(as
are vinyl windows)...so my advice(take it as such) is, if you arre going to
keep the storm windows for screens, then don't ever completely shut the glass
sashes in them...keep them open, at least a bit to ventilate any heat buildup
during times of direct sunlight....
-------------------
Chris Perdue

"Sometimes you're the windshield, sometimes you're the bug!"

Remove "PANTS" to e-mail

Chris Perdue wrote:

you will get very little benefit from the storm windows in the form of R
value...

Au contraire, you'll get another US R1, or perhaps more, with low-e.

some wind resistance, but that is not a problem with new weather
stripping and sashes, especially double paned glass...

Double-pane R2 becomes R3, a 50% improvement.

...heat build up *is* a major concern ,even in the winter time...heat from
direct sunlight can build up between the storm sashes and your window sashes
very quickly even in the winter time...the vinyl jambliners are prone to
warp at about 150-160 degrees (F)(as are vinyl windows)...

If 250 Btu/h-ft^2 (full sun) were to hit the storm window (unlikely, given
the angles involved) on a 30 F day and the window passed 225 and the screen
absorbed 20% of that, ie 45 Btu/ft^2, and that heat moved to the outdoors
via an R1 storm with no air leaks and to 70 F indoor air via an R2 window,
the net heatflow out of the storm window would be (70+45xR0.5-30)/(R1+R0.5)
= 42 Btu/h-ft^2, so the temperature near the screen would be 30+42xR1 = 72 F.

Nick

I say use them unless your windows are black or dark brown, You wont
warp or get to 150 - 160f ever. You wont even get to 100 in winter. If
they are good yes you get R1, + less wind infiltration. Dual pane Argon
should be R 3 - 3.3. adding 1 R is significant since windows are your
main source of heat loss as is your attic.

From: ransley

windows are black or dark brown, You wont
warp or get to 150 - 160f ever. You wont even get to 100 in winter.

this is untrue....try a simple thermometer placed between the storm and a
window even in the winter time....winter time is less extreme, but full sun in
summer will *very* quickly exceed the 150-160 degrees necessary to warp
vinyl...this is all assuming the storm windows actually seal decent....this is
precisely why vinyl window manufacturers will NOT warantee a vinyl window that
was used in conjunction with a storm window(in my area , not sure of others..)
-------------------
Chris Perdue

"Sometimes you're the windshield, sometimes you're the bug!"

Remove "PANTS" to e-mail

nicksanspam

Au contraire, you'll get another US R1, or perhaps more, with low-e.


okay i can go with that...

If 250 Btu/h-ft^2 (full sun) were to hit the storm window (unlikely, given
the angles involved) on a 30 F day and the window passed 225 and the screen
absorbed 20% of that, ie 45 Btu/ft^2, and that heat moved to the outdoors
via an R1 storm with no air leaks and to 70 F indoor air via an R2 window,
the net heatflow out of the storm window would be (70+45xR0.5-30)/(R1+R0.5)
= 42 Btu/h-ft^2, so the temperature near the screen would be 30+42xR1 = 72 F.



Nick, not sure what this has to do with a storm window harboring heat and
warping vinyl jambliners, but thanks?
-------------------
Chris Perdue

"Sometimes you're the windshield, sometimes you're the bug!"

Remove "PANTS" to e-mail

Well the storm windows are older and aren't that tight,so there would
be some ventilation to prevent some heat buildup.And the jambliners
are vinyl.
I live in New England.
The sashes I'm looking at are all wood inside and outside,so I'm
mainly looking at keeping the rain and snow off the painted wood
exterior during the winter.I didn't really expect any R value
improvment(from the storms) but if I do,even better.

Chris Perdue wrote:

If 250 Btu/h-ft^2 (full sun) were to hit the storm window (unlikely, given
the angles involved) on a 30 F day and the window passed 225 and the screen
absorbed 20% of that, ie 45 Btu/ft^2, and that heat moved to the outdoors
via an R1 storm with no air leaks and to 70 F indoor air via an R2 window,
the net heatflow out of the storm window would be (70+45xR2-30)/(R1+R2)
= 43 Btu/h-ft^2, so the temperature near the screen would be 30+43xR1 = 73 F.

Nick, not sure what this has to do with a storm window harboring heat and
warping vinyl jambliners, but thanks?

That's your wintertime meltdown calc, 73 vs 150 F. You are welcome.

In summertime, we might see (90+45xR2-90)/(R1+R2) = 30 Btu/h-ft^2 of
heatflow with a temperature near the screen of 90+30xR1 = 120 F, if
the storm windows stay closed.

Nick

nicksanspam


That's your wintertime meltdown calc, 73 vs 150 F. You are welcome.

In summertime, we might see (90+45xR2-90)/(R1+R2) = 30 Btu/h-ft^2 of
heatflow with a temperature near the screen of 90+30xR1 = 120 F, if
the storm windows stay closed.



i'm welcome? either you need to reword or clarify because it makes no
sense....all this talk of "at the screen"....the screen is on the *OUTSIDE* of
the airspace between the window and storm window...this is not even relevant to
the heat buildup INSIDE the airspace....where temps DO get hot enough to warp
vinyl...been doing this too long to let someone with a fancy math formula to
overrule actual damage done by direct sunlight heating the airgap BETWEEN the
two windows....who gives a rats ass about how much heat is transfered OUT the
storm when we are trying to stop damage to the window?

"you are welcome"
-------------------
Chris Perdue

"Sometimes you're the windshield, sometimes you're the bug!"

Remove "PANTS" to e-mail

Chris Perdue wrote:

That's your wintertime meltdown calc, 73 vs 150 F. You are welcome.

In summertime, we might see (90+45xR2-90)/(R1+R2) = 30 Btu/h-ft^2 of
heatflow with a temperature near the screen of 90+30xR1 = 120 F, if
the storm windows stay closed.

Of course they needn't.

i'm welcome?

Sure. You said thanks. I said you are welcome.

either you need to reword or clarify because it makes no sense...

Perhaps not. It takes two to make sense.

all this talk of "at the screen"....the screen is on the *OUTSIDE* of
the airspace between the window and storm window...

Why didn't you say so? My screens are *****INSIDE***** the storms!!!

this is not even relevant to the heat buildup INSIDE the airspace...

Of course it is. Screens block sun. Interior screens warm
spaces between glass. Exterior screens cool them.

which where temps DO get hot enough to warp vinyl...

"Which where?" I suppose you could melt vinyl on a hot sunny day, with lots
of dark trim surface, if you were dumb enough to leave the storm windows
closed with no screen on the outside.

....who gives a rats ass about how much heat is transfered OUT the
storm when we are trying to stop damage to the window?

People who understand Ohm's law for heatflow. If an interior screen absorbs
20% of the 90% of full sun (250 Btu/h-F-ft^2) that enters an R1 storm window,
ie 0.2x0.9x250 = 45 Btu/h-ft^2, with 30 F outdoor air and 70 F room air
behind an R2 window, we have (viewed in a fixed font like Courier):

T = temp between window and storm
|
R2 | R1
70 F ---www---*--X--www--- 30 F
|
45 Btu/h | Temporarily opening the circuit at X, we can easily model
--- | the part to the left of X with a Thevenin equivalent...
|--|--|-- Opening the current source, some of us see that Rt=R2.
--- The open-circuit voltage Vt = 70+45xR2 = 160 F.

T
Rt=R2 | R1
---www---*--X--www--- 30 F
| I -- I = (160-30)/(R1+R2) = 43.3 F,
--- Vt = 160 F
- so T = 30+43.4xR1 = 73.3 F,
|
- not "150 or 160 F."

Have a nice day.

Nick

nicksanspam

I suppose you could melt vinyl on a hot sunny day, with lots
of dark trim surface, if you were dumb enough to leave the storm windows
closed with no screen on the outside.

"dumb enough"? for a, i guess "smartguy" you don't read well....i had addressed
this in my *FIRST* post...

People who understand Ohm's law for heatflow. If an interior screen absorbs
20

snip excellent tutorial

your math formula is nice, and i appreciate you trying to educate, but i need
not understand your formula to know that i have removed warped vinyl windows
that no longer seal (because of warpage) due to storm windows being left in
place....BUT i will *withdraw* my original suggestions and let the OP go with
what the manufacturer recomends as far as the storm windows with the vinyl jamb
liners...(i'm fairly certain what the manufacturer recomends)

Chris Perdue

YIKES!!
I didn't think this would be such a HOT topic.
Still not sure the correct thing to do but I appreciate both of your
points of view.
I guess I could leave the storms on but leave one open enough(maybe an
inch or 2)to let it ventilate.

From: maistomeadows

Still not sure the correct thing to do but I appreciate both of your
points of view.
I guess I could leave the storms on but leave one open enough(maybe an
inch or 2)to let it ventilate.


i say go with what the manufacturer recomends...can't go wrong
there...especially if you want to be covered by warantee
-------------------
Chris Perdue
"I'm ever so thankful for the Internet; it has allowed me to keep a finger in
the pie and to make some small contribution to those younger who will carry the
air-cooled legend forward"
Jim Mais
Feb. 2004