Beads in frame of insulated glass window

[hrhofmann]

I have some 25 year-old double-hung windows that supposedly have double vacuum glass for the glazing. They have been cloudy between the two pieces for many years, but I didn't get around to working on them until yesterday. I removed one of the glass assemblies to see how thick they were and the exact dimentsions so I could order some replacement glass units from my local glass store. I have used the store to prefabricate glass to replace some other window units about 9 years ago with great results. As I was removing the two layers of glass from the aluminum frame that separated them, the aluminum frame separated at one of the corners and a zillion (well maybe only a million) tiny white beads came out of the frame. They were about the size of sprinkles on chocolate mints. I am guessing that maybe the windows weren't really vacuum sealed, but depended on the beads to absorb any moisture that headed in their direction.

Does anyone have any experience with these types of windows they can share?

[dpb]

That would be a dessicant.

Generally, you're best recourse would be to have new doublepane units fabricated for the windows. If you're lucky, they have the wherewithal to make them the same thickness or thinner than the existing panes/dividing holders. Inert-gas-filled are better choice than vaccuum...

[hrhofmann]

Yeah, that;s what I'm planning on doing if I decide not to just replace the entire windows. I have 3 months to doing pricing, I fgure now that it is winter here in the Chicago area I can get the best prices on full windows as well as on glass inserts.

[Oren]

Something I learned today that I never really paid attention too before. The U-Factor of a window glass. (lower the better)

"What is a Window U-Factor?"

The U-factor measures how well a product prevents heat from escaping. The rate of heat loss is indicated in terms of the U-factor of a window assembly. U-factor ratings generally fall between 0.20 and

1.20.

In the United States, the U-factor is usually expressed in Btu/h ft² F. The metric equivalent unit is W/m² K.

The insulating value is indicated by the R-value, which is the inverse of the U-factor. The lower the U-factor, the greater a window''s resistance to heat flow and the better its insulating value. The U-factor is included in the energy performance rating (label) offered by the National Fenestration Rating Council (NFRC).

[Tony]

Is that your opinion because they last longer or they have a higher r-value?