SWISCO - The Replacement Hardware Authority

balance spring strength

A handy person from Stuart, FL says:
Nuair window 60" height by 51" width. The window being lifted by the balance springs weighs 27 pounds. The balances that are in the window from the manufacturer are 29 5 EX CMC 2. The metal is 30" long and with the plastic guides the length is 31". Are the springs correct or too strong or too weak? If incorrect, what should they be? Picture included.
A customer submitted photo of channel balance attachments.
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Tom from SWISCO responded:
Thank you for posting in our discussion board. Before we can offer a suitable replacement for your channel balance, we just need to know a bit more information about your attachments

Please refer to the following chart and pick out your bottom shoe from the examples given. This will help us determine your balance Series.
A SWISCO guide to identifying balance shoes.
A handy person from Stuart, FL says:
Yes. 1 and 1/16. As you can see in the picture that I included the first time, they don't look like the ones you are displaying.
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Tom from SWISCO responded:
Thank you for the information. If at all possible, can you recheck your measurements? We do not have any bottom shoes of that style that measure 1-1/16". Just by eye-balling it, and considering that your measurement was above 1", I think it may be our 15-004, but I would just like to make certain before I say anything definitive.
A handy person from Stuart, FL says:
The measurments are correct to a 32nd.

Does a 32nd of an inch one way or another dictate the spring strength?
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Tom from SWISCO responded:
Before we can answer your first question, we need to determine your balance Series, which is based on your top and bottom attachments. Your Series is also what ultimately dictates what stamp options you have available. The stamp option is what we need to reference when determining what weight your balance can support.

Normally, a channel that is stamped with "29 5" translates to 2950. A 30" non-tilt channel balance with 2950 will carry a window sash weight range of 28 through 32 pounds.

If you feel this is too strong, the 2940 stamp option will carry a window sash weight range of 23 through and including 28 pounds.

This information is based on 2 balances per sash. Balances are designed assuming friction in the jamb weather-strip will carry a portion of the sash weight. Suggested sash weights are approximate.
A handy person from Stuart, FL says:
Thank you for your answer. Because the window weighs 27 pounds, I could step down to the 29 4 as you say. I will think about this.
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