sash support

A quick learner from FL says:
I have tilting windows. The sash support is 29 inches long and has a number stamped r C 2840 on the back. I assume I need a 770. When I tried to order I was told that I need to select Option 29A, 29B, etc. I could not find an explanation of the different options. What option do I need?
Profile picture of Tom
Tom from SWISCO responded:
Thanks for posting! As stated on the S770-29's product page, the stamp option represents the strength of the channel balance. More often than not, you can locate the stamp on your channel balance. However, in your case, that does not seem to be the case.

Your best bet at this point is to weigh your window sash and compare its weight to each option for the S770-29. The weight range for each option are as follows:

-29A: 7 through 12 pounds
-29B: 12 through 18 pounds
-29C: 18 through 23 pounds
-29D: 23 through 28 pounds
-29E: 28 through 32 pounds

Please keep in mind that the weight range information is based on 2 balances per sash. Balances are designed assuming frictioan in the jamb weather-strip will carry a portion of the sash weight. Suggested sash weights are approximate.
A quick learner says:
Thanks for the reply. My window weighs 25 pounds and I have two balances per window. Do I need the S770-29B or the S770-29D? I assume it is the S770-29B.

Thank You
Profile picture of Tom
Tom from SWISCO responded:
Thank you! Actually, you'd want the 29D. Since your sash is 25 pounds, it fits within that weight range. Remember, these ranges are already taking into account that there are two balances per sash.
A quick learner says:

I placed my order
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)