Coil balance assembly for 50 LB window sash

A handy person from North Carolina says:
I have already received parts for my smaller windows from SWISCO, they used an 8.5 lb spring. THis window is much larger and the original manufacture used 3 springs in tandum as you can see, All the other parts are the same, so do I just use a stronger spring for use with this window or do i need a completely different assembly? My original parts order was 1868775 FYI
Thumbnail of the uploaded file named 7A21E1E4-37AD-404F-92B0-F470C9F1E8B4.jpeg
Thumbnail of the uploaded file named 62A2B7EF-69EE-4015-A5A5-F8F73C17857F.jpeg
Profile picture of Emily
Emily from SWISCO responded:

Hello!

It looks like you have a triple coil assembly which is very uncommon for this pivot Simonton or CertainTeed shoe. These are only designed to use 2 springs maximum . The fact that the original installer used 3 means that this is bit of a rig. 

To make matters worse, we don't sell any S171 springs that carry more than 7 pounds, so you won't be able to use the 15-192 . With that said, you will need to use our Simonton conversion process as shown in the video below. The S159 springs come in at 8.5 pounds and (6) of these would total 51 pounds of overall support. However, keep in mind that these are also not meant to be used 3 per side and we only sell covers for 1 and 2 springs. We have no idea if you'll be able to get 3 coil springs per side to work, we've never tried and it is not recommended. You're going to have to experiment to see if this could be possible. I apologize we can't offer a better solution. 

SWISCO S170 and S171 Coil Balance Assembly
SWISCO S170 and S171 Coil Balance Assembly
VIDEO
WATCH >
How to remove window pivot shoes
How to remove window pivot shoes
VIDEO
WATCH >
Anatomy of a tilt window
Anatomy of a tilt window
VIDEO
WATCH >
How to replace a Simonton coil balance
How to replace a Simonton coil balance
VIDEO
WATCH >
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)
Current wait time is 4-7 business days
We promise that one of our experts will personally get back to you as soon as they are able. Thank you very much for your patience and understanding. If your inquiry is time-sensitive, please feel free to reach us at (888) 991-1929 or at help@swisco.com.