[friesenk51]

I have posted before with questions about ductwork design however I realized that designing a "balanced system" is more than likely out of my "overly aggressive" do it myself realm. I contacted the installer of my current furnace (furnace was put in 9 months before I bought the house). He stated that he used a fancy program and he feels that the system size is correct. He stated that he calcualted the home with new windows and not the current windows.

My question is this, I have read in books (builder books at home depot and online) that "winterizing" your home is the best way to help reduce energy bills, wear & tear on the furnace. By winterizing I mean making sure that all cracks are filled, etc... and that windows are your "last resort". Is this proffessional right that all new windows (single pane with storm to double pane low e) is going to make that much of a difference? my house is 73 yrs old