Series 159 Coil Balance Quote

Thanks for posting. If you are certain this is the old Simonton system that can be replaced by the 15-259 shoe and Series 159 springs (see the video below), and if the window sash weighs 16.7 pounds, you can use the S159-08 8.5 pound springs, one for each side of the sash. This will each 17 pounds of support overall, which is close enough to the exact sash weight. Let me know if you have further questions.