Double pane glass windows also go by the name of thermal windows and dual pane windows. These windows contain two panes of glass with a layer of air in between. Properly functioning double pane windows have a vacuum seal that provides a form of thermal insulation, helping to keep your home energy efficient. If the seal malfunctions, the space in between the windows can become dirty and foggy.
As long as the seal around the edges of the two glass panes remains intact, the area between the glass will remain clear and free of fog and debris. Although many double pane windows contain a vacuum seal between the two panes of glass, some windows contain a type of gas known as argon. Over time, constant exposure to sunlight, as well as contraction from hot and cold temperatures, may cause the seal to crack, allowing the outside air to enter the space between the two sheets of glass.
The first sign of a failed seal in a double pane window usually appears as moisture, or condensation, on the inside of the glass. Fine particles of dust may enter the opening, eventually causing a buildup of film on the interior of the panes. Cleaning the exposed surfaces of the window glass fails to remove this film. As the moisture continues to build up inside the panes, you may see streaks forming in the dusty debris, making the problem more noticeable.
The most common method of resolving the problem of leaking seals in double pane windows is to replace the entire sealed glass unit, keeping just the frame. Depending on the type and brand of double pane window, your sealed unit may last 10 to 20 years. Replacements within this time frame may be covered under a warranty.
Repairing a sealed window unit requires more than simple caulking, making it difficult for the average homeowner to reseal a failed double pane window unit. A window repair service may be able to save the window, however. The repair process involves drilling a small hole in the top and bottom of the outer pane of glass. After cleaning the area between the panes by spraying in and sucking out certain solutions, the repair service uses a drying agent to remove moisture. The final steps involve creating a new seal and installing valves to prevent air from entering the sealed area.