Help request on identifying steel window channel balances

Question

Hello~
I have 2 questions regarding replacing steel window channel balances.
1. Through the pictures I uploaded, I think I need some 29" Series 770 Balance (Product Code: S770-29) Could you help me identify the correct part, and also confirm if this is the write part.
2. I see 29C was carved on my old parts. I understand 29C has a sash weight range from 18 to 23 lbs. I wonder what happens if I choose 29D. 29D has a sash weight range from 23 to 28 lbs. Will 29D make me open and close my window easier or harder with more sash weight?
Thanks a lot!

Lauren · Accepted Answer

Hello, thank you for posting,

I agree that your original balance resembles the Series 770 channel balance. If you choose a stamp for a higher sash weight, the spring would have too much tension and cause the window to not close correctly.

If you are uncertain if the 29C stamp range was correct originally, I recommend weighing the window sash to confirm. Let me know if you have any additional questions!