coil replacement needed

A home owner from Montreal says:
Hi,
This is part one of two posts. These photos are from the upper window. I have found the identical parts on your website. Unfortunately I don't see any information about the coils on the existing ones. It's a 1/3 - 2/3 set-up, with the bottom window (2+2 coils) weighing 20.4 lbs and the top (1+1 coils) weighing 10.8 lbs. Could you let me know which coils I should order?
Also, is the pivot shoe 15-191 (heavy duty)more durable that the 15-111 or is there another difference.
Which would you recommend?
Thumbnail of the uploaded file named 20190914_135956.jpg
Thumbnail of the uploaded file named 20190914_140025.jpg
Thumbnail of the uploaded file named 20190914_140035.jpg
Thumbnail of the uploaded file named 20190914_140108.jpg
Thumbnail of the uploaded file named 20190914_140405.jpg
Profile picture of Tom
Tom from SWISCO responded:

Thanks for contacting us. So, if I'm understanding your post, your bottom sash has four springs supporting it (two on each side) and weighs 20.4 pounds, while the top sash has 2 springs supporting it (one on each side) and weighs 10.8 pounds.

That's easy enough to figure out. The next step after you have that information is to just divide the weight by how many springs support it. Can you just confirm the thickness of the spring? It looks like our 1/2" thick Series 160. Assuming I'm right, the bottom sash would use one S160-4 and one S160-5 on each side (4.5 lbs + 5.5 lbs = 10 lbs, 10 lbs x 2 = 20 lbs) and the top sash would use one S160-5 on each side (5.5 lbs x 2 = 11 lbs). 

The 15-191 is considered more durable than the 15-111. That's why it's labelled "heavy duty."

A home owner from Montreal says:
Perfect. Thank you. That is exactly the info I need. The coils are 1/2 inch and you interpreted my explanations correctly. I will place my order immediately.
Profile picture of Tom
Tom from SWISCO responded:

Sounds great. We are happy to have been able to help you get pointed down the right path to the replacements you need. 

How to replace a window coil balance
How to replace a window coil balance
VIDEO
WATCH >
How to Replace a Triple Coil Balance System
How to Replace a Triple Coil Balance System
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 >
Removing a Triple Coil Window Balance
Removing a Triple Coil Window Balance
GUIDE
READ >
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 3-4 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.