Why are my windows wet?

Q: Moisture collects inside one of the double-pane windows in my house. I can get most of it out with a blow dryer, but is there a better way?

A: Associate editor Daniel S. Morrison replies: Condensation indicates that the seal between the panes is leaking. Moisture leaks into the panes, then condenses on the cool inner surface of the glass. The heat from your blow dryer makes the moisture evaporate, but as soon as the glass cools, moisture condenses on the glass again. Most reputable window manufacturers offer a 10-year warranty on the window seals. If the window is older than that, you probably have gotten your money’s worth, and it’s time to replace the sash. If not, check the warranty. You may be able to get free (or discounted) window replacements.