We bought our house a little over a year ago. We house is only about 2-3 years old. This past spring we ripped out the Air Source Heat Pump and put in a Geothermal closed loop system.

My question is, how can we tell if the windows are single or double pane? Last winter on some of the coldest days there was condensation on the inside and some of the condensation froze.

From the one sticker in the window in the attic dormer they are Jeld-win windows.

Thanks,
Dennis

You should be able to look at the window and tell whether you see two layers of glass or just one layer. If it is dual pane there will be two sheets of glass with a space between them (maybe a quarter to a half inch of space).

Thinking about it we have the window grids inside the window... so it has to be double pane.. my guess is just not very high quality double pane. Would an external storm window help much with the heat loss?

You should be able to see an adequate space between your windows glass panes.

We are thinking of installing some storm windows with Low-E glass this summer.

heimdm, if it was just one of the windows that had condensation, then it could be possible that one of the panes of glass was broken. What is your climate like - in what part of the world are you located?

The condensation happens on just about all of them. We are located about 30 miles southwest of Indianapolis, IN. When outside temperature reaches around 0-20 degrees we notice the condensation.

I guess they could just be really cheap? I used to live in Germany and we would have sub-freezing temps for weeks or months on end, and our double pane windows never had condensation on them. But you could see which houses in the neighborhood had single pane windows, because the condensation would literally be dripping down the inside.

The obvious problem is that for some reason the inside surface temperature falls below the dew point.

It could be a bad seal, a thermal bridge in the window frame or air infiltration.

Jelly, I'll bet you had radiators under or adjacent to your windows, correct?

Putting heat on the inside surface is another way to keep the inside surface temp of the windows above the dew point.

Bruce

heimdm,
What's the humidity level in the house? Maybe what the condensation is telling you is you need to install a ventilator to bring in fresh outside air and exhaust stale inside air.