Check the weep holes on the outside. Occasionally they can get stuck in the open position and that would cause the problem you describe. If that doesn't solve the problem, get in touch with either the installer or the local Simonton distributor.

We have these exact same windows and seem to have the same problem but perhaps not to the same extent (we are not considering replacement). Many of our windows are egress windows (designed to open further than a standard window) and we have them all over the house not just in bedrooms. Subjectively it seems that these windows have more air infiltration than those without this option. I wonder if the modification done to make these have a larger opening for emergency egress has something to do with the air draft? The egress windows all have a piece of plastic visible on the side track of the windows. This is not visible on the windows without this option. Skydawwgy or others can you give your opinion on this? Otsbork, did you contact Simonton about this? Thank you!

Other than the weep holes, the weatherstripping on the bottom sash or a poorly fitted sash, the only thing I can tell you is ten years ago the Pro-Finish was made as a budget window and doesn't have as low an A/I rating as some of the other windows on the market. It was originally designed to appeal to builders on price point. I'd still recommend calling Simonton or a local distributor and see what they have to say.

We had the same "updraft" problem on our windows right after they were installed. A Simonton rep came out and installed what I believe he called a "chimney plug" in all the windows. The plug is just a thin piece of foam weatherstrip extruded to fit into the bottom of the sash channel and lay flat to the sill, it's about 1/8" thick. It stopped the draft problem. Simonton knows that the draft is a problem because they shipped the pieces to him the next day. Call a Simonton rep.