Need some advise. The current coil balance on my window has 2 springs each side (see picture). Using your calculation, window size = 20.75" x 33.5", double insulated, the window sash calculation comes out to 8lb per side. This means i can go with a single 8lb spring each side.Correct or should i upsize it?
The product code for the 8lb replacement is S140-8.
