Replacement balances

A quick learner from Venice FL says:
I have 2 different windows weights and need to know if I need different parts for the heaver windows.

The broken part number in the photo 12:10:58 09/23/04 Unique Balance 27F All of the broken balance measures 28" long with the U shaped channel 1/2" X 1/2"

There are two windows sizes with different weights the 34" window weighs 28.8 lbs. and the 50" window weighs 41.8 lbs.

Do I need different parts for the different weight windows and if so what part numbers.

I will need 6 of the 41.8 lbs. and 14 of the 28.8 lbs. parts
Thank John
User submitted photos of a window balance.
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Tom from SWISCO responded:
Thank you for posting, John. This balance looks a lot like our Series 770 channel balance. Can you confirm the length of the metal channel though? With that stamp, it should be 27".

If it is, then we're looking at two different options for the S770-27. The first option should be 27E, for the 28.8 pound window. Two S770-27 balances with the 27E option can support a window sash weight of 26 through 30 pounds.

The second S770-27 will have to be custom made, as we do not have a standard option that can support 41.8 pounds. Check out this Custom Channel Balance Request Form I've started for you based on these specifications. This balance has a special 27H option, which can support 38 through 42 pounds. Once you fill out and submit the rest of the information on this form, one of our representatives will get back to you with a price quote and an item to add to your cart with whatever else you choose to purchase.

Review this information and let me know what you think. If your balances are, in fact, 28" long, let me know and we can try to figure out what you have from there.
A quick learner from Venice FL says:
The balance channel is 28 in. long, but the spring is pinned at the 27 in length. The top has a mounting hole in the upper 1 inch but the distance from the spring top to bottom of channel is 27 inch.

In the photo you can see the mounting hole and on the side the holes for the spring pin.

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Tom from SWISCO responded:
Ah, I see. It's better to go with the length of the channel then, yes. With that in mind, I think you should instead look at our S770-28 with the 28E option for the first balance, and then this Revised Custom Channel Balance Request Form for a 28" long Series 770 balance with a 28H stamp. 28H can carry 40 through 43 pounds.
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