We purchased our home in 1998. It has pella double-pane windows that have the blinds between the panes that had been installed approximately 3 years previously according the prior owner. In 1999 we noticed some dampness and discoloration of the wood frame of the bay window. Pella send a representative to the house who promptly told me that it was my fault for not cleaning the vents properly and allowing condensation to build up. I have since religiously cleaned the vents and have ultimately removed one of the panes to better monitor the... read full review »