constant force balance - Replacement parts

A home owner from NY says:
am trying to replace constant force balance in the double hung windows. Parts
15-191 - Heavy Duty Pivot Shoes
15-150 - Coil Single Support look the right ones

am not sure about S-160-6 Coil Balance as it looks different from the coil balance (the old one has a bend for additional tension where as S-160-6 is straight) I am replacing. Also if this coil balance is the right replacement, should I be getting S-160-5 instead of S-160-6.

Would appreciate nay guidance and help in getting the right replacement. Thanks!
Thumbnail of the uploaded file named IMG_2798.jpeg
Thumbnail of the uploaded file named window_parts_replacement.png
Profile picture of Bob
Bob from SWISCO responded:

I agree, the pivot shoe looks like our 15-191, along with the 15-150S support. As far as the Coil Balance goes, don't worry about the overall appearance--the Series 160 is compatible with this pivot shoe. However, so is the Series 165. To know which you need, you must measure the thickness of the coil tape. If it's 1/2" thick, then the Series 160 is correct. If it's 3/8" though, you need the Series 165

As far as the right spring weight to select, go by the stamp codes on the spring itself. If there are none or you are uncertain, give me the exact weight of your window sash and I can work it out for you.

A home owner from NY says:
Thanks Bob. The width of coil is 1/2" (if that is what you meant by measuring the thickness) . Not sure about the sash weight. Couldn't find any specs. as there are no stamp codes on the coil nor the sash weight is printed anywhere. Just weighed it on a scale and is between 6.8 - 7.0 lbs. It measures 20 1/2" X 17 3/4".
Attaching some pix of the window as well.
Profile picture of Bob
Bob from SWISCO responded:

I would double check that exact sash weight to be safe, since it seems pretty light, but if so, then using (1) of the S160-3 3.5 pound springs on either side of the sash should work well. That will equal 7 pounds of support total--and yes, 1/2" wide springs mean you need the Series 160

A home owner from NY says:
Thanks for a quick response. Is there any downside to going with 5.5 lbs is the sash weighs approx 7 lbs?
Profile picture of Bob
Bob from SWISCO responded:

Yes. If you went with the S160-5 5.5 pound springs, that would equal 11 pounds of overall support. This is significantly higher than the weight of your 7 pound sash, and would result in the window being very difficult to close or keep closed. With window balances, you want the weight range to be as close as possible to the actual weight; with coil balances specifically, being within 1 pound is best. 

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)