Coil strength and Single coil vs Double coil

Question

My house still has the original Simonton Norandex windows from the mid-late 90's. Rather than dealing with replacement windows, I'd rather refurbish the ones I have with new hardware and weatherstripping. Comparing my items to your pictures, and based on other users' questions, I've identifies the replacement Pivot Shoe (15-111) and coil series (S160) for my windows. My windows are various sizes, but the sashes generally fall in four weight categories: 13.75 lbs, 15.5 lbs, 15.75 lbs,and 17.75 lbs.

If I may, I have two questions:

1) Do I try to match (as closely as possible) the coil poundage to my sash weight? And if so, what do you do if the sash weight is in the middle? (ex: for the 15.75 lb sashes, with 2 coils on each side: 4 @ 3.5 lbs = 14 lbs, but 4 @ 4.5 lbs = 18 lbs) Is it wiser to go with the weaker or stronger coils?

2) Is there an advantage to using two coils on each side, rather than a single coil on each side? (ex: 2 @ 3.5 lbs vs 1 @ 7 lbs)

Thanks for your help!

John

Paul · Accepted Answer

Hello! I will do my best to answer your questions.

First, the best way to match up your springs is by going off of the numbers on your old springs. They usually tells you exactly what you should go with, especially if you found that your windows worked fairly well up 'til now.

That said, I'll briefly make a few suggestions for the sash weights you detailed:

-For the 13.75 pound sash, I recommend four S160-3 springs.
-For the 15.15 sash, I recommend two S160-4 and two S160-3 springs; you would use one S160-4 and one S160-3 on each side.
-For the 15.75 sash, you would use the same as above.
-Finally, for the 17.5 pound sash, I would use four S160-4 springs.

For your second question, there is no advantage for using more coils. We highly recommend trying to copy what the manufacturer went with.