SWISCO - The Replacement Hardware Authority

Balance spring replacement

A quick learner from Murfreesboro Tennessee says:
For double hung tilt vinyl window. Only marking is most likely a serial # si92899. 3/8" but I don't know where to start/stop on measuring the spring length. Top of the coil itself to the bottom of the coil is 27" but there's other parts attached too.
User submitted photos of a window balance.
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Paul from SWISCO responded:
We should be able to help, but I would like you to confirm a couple details. First, what is the length and diameter of the white outer tube? Also, what is the weight of the sash?
A quick learner from Murfreesboro TN says:
The vinyl outer tube also measures 27". How do I determine the weight of the sash? The window measures 57" x 29.5" if that helps.
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Paul from SWISCO responded:
You will need to place the sash on a scale to determine the weight. Also, just to confirm, is 3/8" the diameter of the tube or the inside coil? The most important diameter measurement is for the tube, not the coil.
A quick learner from Murfreesboro Tennessee says:
The weight of the bottom sash is 14 pounds approximately. The coil is 3/8" but the vinyl cover is about 7/8".
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Paul from SWISCO responded:
Thanks. I would wager the outer cover is actually more like 5/8" or 9/16". I do not believe they make a 7/8" balance but 5/8" and 9/16" are common. I would recommend our S600-27 spiral balance with a red tip option.
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