We had a similar decision to make except that the casements were to open into a screened porch and we were concerned that while on the porch, people might run into them. We have double hung windows with grills on the top half all throughtout our home but I didn't want my sink centered on a middle piece of wood between two casements. Was just something I didn't personally like for our kitchen. We then saw a similar window to what is in my most recent post which has sliders where the side casements usually are and a large picture window in the middle. WE LOVE IT because it gives us unobstructed view, still has the venting options, screens are on the outside and we felt that having the option of the grills on the side windows, helped it to look more traditional like the rest of the windows in our home....our window is one of the best choices we made - we just love it! I copied my link to my pictures below....you'll see it in the 4th pic down over the sink. Here is a link that might be useful: imlebby's kitchen

Jocobe, I think that you are misunderstanding the problem. The upper sash is not drifting, It stays up. The problem is that when the window is locked, there is still a gap. Balances have absolutely zero to do with this, as the materials have either shrunk, settled, etc to cause this as has been mentioned already. Bottom line: the windows are due for replacement. To fix it for now (until budget permits replacement): either add a thin piece of wood to the sill or head, or add additional weatherstripping to one or both. You can buy stick-on foam bulb seal in rolls from the store that would probably do the trick for a while. Shimming the lock/keeper would be another option. Ultimately, what you are trying to do is fill in the frame to take up the "slop" that is present when you move the sashes up and down when they are locked together.

Has anyone heard of Kasson and Keller that make Eco Shield 4000? It is very hard to find a review on these windows. I like the DSL (divided simulated light grids), the price is nice too.

Sounds to me like they make have pressure coming down on them and if so there is really noway to fix this. Are they surrounded completely by wood and if so is the header piece level or bowed down in the middle ?