I have the Pella Designer casement windows. As I've mentioned in the
past, I have huge condensation problems with them even with very low
RH. I'm below the recommended 30% for 0-10F...and they still go crazy.
I have a few windows that aren't of this type, and they do just fine.
At some point, these windows just need to go.

The one thing I wanted to try is to see if the 3pane has less issues
than what is in there now (probably 2-pane). I've heard from a few
people that they've had some 3 and 2 pane Designers; their 2[anes had
issues, but the 3panes did not. Does anyone know if the 2pane and
3pane inner glass panes are interchangeable?