SWISCO - The Replacement Hardware Authority

Required number for sash window balance

A quick learner says:
for item S390-30, requires a number (2910 - 2950) for adding into shopping basket. How do i know which number to click on which will reference to S390-39
Profile picture of Donna
Donna from SWISCO responded:
The required number option is a number that can normally be found on the original balance, it indicates the strength. If you cannot locate the stamp number, please remove the window sash and place it on a scale. The weight of the window sash in pounds is needed to determine the proper stamp option.
A quick learner says:
Thank you Donna.
There are two sizes of window
The weight of Windows are:-
(a)larger window is 36 lbs.
(b)smaller window is 24 lbs.
Profile picture of Donna
Donna from SWISCO responded:
You had mentioned S390-30 and S390-39.
I am assuming the 30" balance is for the sash that weighs 24 pounds and the 39" balance is for the sash that weighs 36 pounds, please correct me if I am wrong.

The S390-30 with stamp option 2940 will carry a window sash weight range of 23 through 28 pounds.

The S390-39 with stamp option 3850 will carry a window sash weight range of 30 through 36 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.

I can email you a custom ordering link for the 39" balances, just need quantity.
A quick learner from Florida says:
sorry, my typing mistake.
Both window balances has the same length of 30".
I would need total 12 balances. 11 for windows weight 24 lbs. and 1 for window weight 36 lbs.
Should the order for the 24lbs sash be: S390-30 Stamp option 2940?
What will be the stamp option for the larger 36 lbs sash?, it has channel balance length of 30" also.
Profile picture of Donna
Donna from SWISCO responded:
I can look into custom ordering the custom weight balance for you, 36 pounds is heavy for a 30" balance, the standard options will not work.
You asked for 1 but it is recommended to replace both balances at the same time, replacing both window balances at the same time prevents extra wear-and-tear to the new balance, which will have to work twice as hard when paired with an old balance. Do you still only want to order 1?

The S390-30 with stamp option 2940 will carry a window sash weight range of 23 through 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 quick learner says:
Please order 2 balances for the 36 lbs window .
I will need 12 balances S390-30
Please advice how to do this order, so we can have all shipped together.
Profile picture of Donna
Donna from SWISCO responded:
I will email you a custom ordering link for (2) 30" Series balances for a 36 pound sash shortly. You will be able to add other needed hardware to your cart.
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)