Proper weight for a Series S180 coil

Question

2019 I ordered and replaced both workings on my tilt out window. Finding the coil number was not easy (9 or 6 or?) So with the window out and weighing 20.4 pounds I want to be sure I'll re-order the correct coil for that weight. The recommendation was for 5# coil but then a further e-mail stated that most likely 6# coil would have been correct. The window has been fine now for 6 years with the 5# coils but one side now has a broken coil.

Question is, should I order for bother sides and with the window at the 20.4 pounds shall I re-order the 5# or change to the 6# coils. Thanks!

Tom · Accepted Answer

Thanks for reaching out to us. Based on your description, I would recommend using two 5 pound springs per side for a 20.4 pound sash. That will give you 20 total pounds of support, which should be more than sufficient. The difference left over won't be enough to make an impact on how the window operates.

Using two 6 pound springs on each side gives you a total combined weight of 24 pounds, which I would gauge as too strong. You may notice that the sash would be hard to close. In a worst case scenario, it could even open on its own. I wouldn't go up to 6 pounds at all unless you have some reason to doubt the sash weight you already have.

This is doubly the case if your window has been using 5 pound springs for all these years without issue. "Don't mess with success" is a mantra that has served me well in this industry for a long time.