Just received 10 Simonton double hung windows, after they were installed, noticed that they didn’t have low e glass, just air between panes. An oversite, contractor didn’t ask, and neither did homeowner before ordering. Any suggestion? How much difference does low e glass or argon make, they are large windows 46″ X 60″?
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Replies
Many window manufacturers don't label the glass with a little silkscreened logo and info tag, unless the glass is tempered.
Argon gas is invisible in the airspace, and a low e coating is virtually transparent. Unless you are holding a pane with the coating next to one that is bare, you won't know you are looking through it.
The airspace between panes of a dual-glazed assembly is not a vacuum . . . it is just sealed. Argon gas is pumped in and the air is evacuated, and then the thing is sealed up at the little tube ports, to yield a higher insulation value to the assembly. Argon gas has a lower coefficient of thermal transfer when compared to air.
You may in fact have what was expected, but if the packaging is gone, you'll have to ask the supplier to track down the order paperwork and specs.
If you want to know about what you are losing if you did in fact get plain insulated glass, go to a window manufacturer's website, say, Andersen, Marvin, Windsor, Weathershield, Kolbe & Kolbe. Somewhere, digging into spec info, you can find u-values for different glass assemblies.
Edited 8/8/2004 3:23 pm ET by Bob Dylan
low-e is a coating on the glass itself, the coating blocks uv light and limits heat gain through the glass and also saves carpet furniture etc from fading and color changes due to uv light.
The argon or air between is an insulater to improve the r value, and the diff between air and inert gas fills is minimal. hope this helps
There shouldn't be any 'air' between the glass panes. It is either a vacumn or an inert gass.
The Low-E coating on the outer glass surface and its effectiveness defpends somewhat on the climate. Here in Maine, the common belief is that it counts more for limiting damage to furniture than for energy efectiveness.
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If there were a vacuum the window would collapse inward. It's either dry air or an inert gas. There's a theoretical difference between the two, but the practical difference is questionable.
One cheap and easy way to tell if low-e is present is look at the reflection of a flame in the glass. You will see 4 flames reflected. low e will reflect 1 flame a different color where clear glass will reflect them all the same.
Of course you can get a low e detector from cr laurance for $800.00 but a lighter is much cheaper.
I can show you some that do cup inward on larger windows exactly for that reason. The manuf rep told me that it is partly because they were manuf at over 2000' elevation and we are at sea level where the air pressure is higher, along with a bunch of other bs, but it is true they are sucked dry. One reason they have gone to replacing the air with inert gasses is because the failure rate on those older vacumn ones is too high.
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Hate to tell you this but one very well known window company had a problem with "collapsed glass", where the glass looks concave and distorted. This results in breakage and condensation where the glass touches. The remedy is drill a hole through the glass spacer bar then patch the hole.
Bowed glass has nothing to do with elevation and everything to do with a bad manufacturing process.
The size of the insulated glass, the space between the glass and the thickness of the glass itself dictates how much it will deflect (or bow). Big pieces, like in 2 story foyers, can be 1/4" glass with an inch of space in between.
Insulated glass does not have a vacuum....it's either air or argon.
Exactly my bad manufacturing point. Many window manufacturers make the insulated units laying flat on a table, If you use thin glass to save money the bow from gravity will cause a natural vacum when sealed.
Now if you take the same unit and stand it on edge...drill a hole in the spacer magically the bow will disappear.
The different air pressure theory just doen't work. If they where that susceptable to air pressure changes a unit made at high altitude on a summer day would implode during a nice sub zero ,winter, high pressure system, blue bird day.
Piffin ask the window salesman selling you that line about the molecular size of argon gas and will there be the same amount of argon today versus 20 years from now. I hope they don't charge you extra for dumb looks cause you'll get a doosey.
I've been in the window biz, from the manufacturing side, in both commercial and residential. Commercial is typically 1/4" glass both sides, and 1/2" airspace. Rez is 1/8" with airspaces down to 1/4".
Sealed IG ("insulated glass") units are just that . . . sealed. No vacuums. If argon is used, two small tubes are inserted in the manufacturing process through the seal, and one is the inlet for the inert gas, the other is the exhaust for the air when the process is driving in the argon. At the end of the gas-fill process, both tubes are sealed. A sensor is mounted at the exhaust tube that tells the operator when the air is exhausted and argon has displaced everything in the cavity.
Companies that ship IG units up to high elevations, if the units are to reside at those elevations, cannot ship argon-filled units. They ship the glass with one tube through the seal, open, and the installers seal the unit before final installation, on site. This is how it is done in commercial work. I don't know what folks like Andersen and Marvin do.
marvin?
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I'll never tell.....but since it's been done in thousands of houses over the last couple of years I'm not the sole holder of the information. The manufacturer realized this is a problem reducing the efficency of the windows and has a rather fool proof system to repair. 1 person can repair a whole house of windows in a few hours.
A true vacuum would subject the glass to a pressure of 14.7 pounds per square inch, or about 1200 lbs. on a 8" x 10" lite, clearly not a survivable condition.
Sealed windows would be subject to changes in barometric pressure, which are almost always under plus or minus 5%. That would be give or take 60 lbs. on the 8" x 10" lite, or about 0.75 PSI. If the glass can deflect a little and change the volume it encloses, that helps relieve part of the pressure difference.
Because the air applies its pressure very evenly, sealed windows do survive quite well. Usually the seals will leak instead of pressure breaking the glass, which, of course, relieves all the pressure on the glass.
-- J.S.
Some brands may be using low-e as standard but the stuff i've been ordering have always had upcharges for low-e, so unless it's a primium product I would doubt that it was included.
plus were talking like 250 Sq' of surface, would be nice to have best performance but it might have to wait till the next window change out.
here in Ohio Simonton has Low-E standard- there is no up-charge, and there is no necessity to specify it.
As far as I know, that it a national policy for Simonton-check it out before you do anything rash. There may be no problem!