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Replacement Coil Balances for Thermolite double hung windows

A quick learner from West Chester, PA says:
I need to replace several broken coil balances in Thermolite windows. I've attached pictures of one that I have removed that still works. In photo #2 there is an 8 stamped on the coil. Can you help identify the appropriate replacement parts that I would need to repair the window?

Also, the coil in the picture is from a smaller window. There are some larger windows that will need replacements as well but I haven't taken any apart yet. I'm assuming it will be the same plastic parts but the coil may have a different rating.
User submitted photos of a coil balance.
Profile picture of Paul
Paul from SWISCO responded:
Thanks for posting. I recognize this spring. Unfortunately, it has been discontinued and is no longer available. However, the recommended replacement is our Series 150 spring. Check it out and see what you think. I also recommend that you consider our 15-140 shoe. You should be able to re-use your old supports, but just in case you want to replace them as well see our 15-143, 15-144, and 15-145.
A quick learner from West Chester, PA says:
Thanks for the suggestions. I plan on replacing all the parts so I appreciate the appropriate part numbers.

I'm checking out the rest of the windows to see how many I need and will place my order.

One question. Does the 8 stamped on the coil mean it is an 8# coil? I'm guessing it is but want to make sure.
Profile picture of Tom
Tom from SWISCO responded:
Yes, that's probably correct. That said, it wouldn't be a bad idea to weigh your sash just to make sure you have the right strength coils, just in case.
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