Need stronger channel balances

A quick learner from Chicago says:
We live in an old 1907 loft building that was converted from a warehouse. The windows did not stay up, so we replaced the channel balances with new ones. The windows stayed open for a day, but now they barely stay open.. We used the same stamping balances that was in the window...33" stamped 3240....it was a 390 series. We recently replaced one window with a 3250 hoping the new balance would be able to hold the weight better. After a few days, it has also started inching its way down again. It is better than the previous one, but not holding like it should. We are not sure what else to try and was wondering if you have any suggestions for us...a different balance or the same one that can hold heavier weight or adding something to the window.

Thank you,
GG
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Casey from SWISCO responded:
Hi GG,
Are you using two balances per window sash? There should be one on each side.
Please remove the window sash and place it on a scale to get the weight in pounds and get back to us, this will help us determine the proper stamp option.

Here is an instructional video that may help:
A quick learner from Chicago says:
Hello,

Sorry for the delay. I had to get someone to help me take the window out. My windows weigh roughly 41.5 lbs each. And yes, we replaced both channel balances when we took the originals out. If the stamping is too low (meaning the 3250 won't hold it), what our options? We need the 390 series.

Thank you,
GG
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Casey from SWISCO responded:
Thank you for the information. You're right, it appears that the 3250 stamp would not be strong enough, since it only supports a sash weight range of 28 through 32 pounds.

I think that a 3270 stamp would be better. This supports a sash weight range of 39 through and including 42 pounds.

Please keep in mind that 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.

Now, a Series 390 channel balance with a 3270 stamp option will have to be custom made. To begin, please fill out this Custom Balance Order Form that I have started for you. One of our representatives will be in contact with you shortly thereafter.

UPDATE: the 3270 stamp is now offered as an option for the 33" Series 390 balances.
A quick learner from Chicago says:
Good morning,

Based on the thread above our building purchased channel balances, which was a fairly large order. They worked great at first, but are now having difficulty opening and some windows do not stay up. My sashes weigh 41.5 lbs as indicated above. I believe I purchased the 3290 as I was almost at the weight limit for the 3270. Do these need to be replaced ever 3-4 years? Should I go down to the 3270 (will I get more service life out of them)? Please advise.

Thank you,
GG
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Tom from SWISCO responded:
Sorry to hear you're having trouble. We actually don't sell any balance with a 3290 option. According to our records, you purchased four different strength balances: 42 balances with a 3275 option, 18 with a 3270 option, another 18 with the 3260 option, and 4 with a 3250 option.

Can you confirm which of these is the balance giving you issues?
A quick learner says:
Hello, my apologies. Several units ordered balances. I used the 3275 in my unit as I was close to the weight limit of 42 (again, my sashes weigh 41.5 lbs). Not sure why I wrote 3290.

Do these need to be replaced every 3-4 years? Should I use the 3270 or 3275? If I use the 3270, will I get more service life out of them?
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Tom from SWISCO responded:
If the sash weighs 41.5 pounds, then I would go with the 3270 option. This can support 39 through 42 pounds. Any stronger could cause problems. There is no benefit to using a balance that is stronger than what you need, and it can actually lead to the window working improperly. Typically, a balance would last 5-10 years depending on how often it is used.
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