[MarkEkberg]

How do you tell if they have lost thier seal?

 

[bugman]

You'll start to get moisture condensing in between the panes.

Jim

 

[chris u]

Just like bugman said you will get moister in them they will start to fog up.

 

[MarkEkberg]

What about moisture building on the inside of the window?

 

[bugman]

If they lost their seal the moisture will be between the panes. If you are asking about the side that is inside the house it just means that you have a moist environment in your home. A window will always be cooler no matter how many panes it has unless it is heated someway.

Jim