Archive for the ‘Failed dual paned windows’ Category

Failed dual paned windows

Monday, August 23rd, 2010
One of the most common findings a property inspector observes, and one of the most taxing to not only the owner of a property, but to the prospective buyer and both agents involved in the sales transaction is "Failed Windows". Failed hermetic seals ( failed glazing) is most commonly found in early generation dual paned windows, those that were manufactured between the early 80's – up to the late 90's and even in some instances, the early 2000's. Since, most window vendors have refined the process of manufacturing these windows, and failed seals are not as common.
The following article was written by Nick Gromicko, Rob London and Kenton Shepard
Why Double-Paned Windows Fail – Solar (Thermal) Pumping
Although double-paned windows appear to be stable, they actually experience a daily cycle of expansion and contraction caused by “thermal pumping.” Sunlight heats the airspace between the panes and causes the gas there to heat up and pressurize. Expanding gas cannot leave the chamber between the panes and causes the glass to bulge outward during the day and contract at night to accommodate the changing pressures. This motion acts like the bellows of a forge, pumping minute amounts of air in and out of the airspace between the panes. Over time, the constant pressure fluctuations caused by thermal pumping will stress the seal and challenge its ability to prevent the flow of gas in and out of the window chamber. Incoming humid air has the potential to condense on the window surface, if it is cold enough.
Can Failed Windows be Repaired?
Inspectors should be aware that there are companies that claim to be able to repair misty windows through a process known as “defogging.”
This repair method proceeds in the following order:
  1. A hole is drilled into the window, usually from the outside, and a cleaning solution is sprayed into the air chamber.
  2. The solution and any other moisture are sucked out through a vacuum.
  3. A defogger device is permanently inserted into the hole that will allow the release of moisture during thermal pumping.
Inspectors should know that there is currently a debate as to whether this process is a suitable repair for windows that have failed or if it merely removes the symptom of this failure. Condensation appears between double-paned windows when the seal is compromised and removal of this water will not fix the seal itself. A window “repaired” in this manner, although absent of condensation, might not provide any additional insulation. This method is still fairly new and opinions about its effectiveness range widely. Regardless, “defogging” certainly allows for cosmetic improvement, which is of some value to homeowners. It also removes any potential damage caused by condensation in the form of mold or rot. Thanks to the authors of this article.
In my opinion, as in all new products, this method has yet to be time tested, and it is more sensible to replace any failed windows