37lb sash

Question

The original channel balances were stamped BSI-2820. We ordered a pair and they fit, but they could not hold up the sash.

Sash=37 lbs.
Channel length=29 in.

We bought 2 different sets from 2 different places and both sets were to weak to hold up the window.

Can you help? Thanks!

Bob · Accepted Answer

Thanks for posting. This looks like either an S380-29 or S385-29. The difference between these two channel balances is the 'depth' of the bottom nylon shoe, or the 'heel-to-toe' measurement. See the diagram below. Compare both with your old balance to confirm what matches best.

Comparison of the S378, S380 and S385 balance shoes.

The stamp issue is odd. 2820 is far too weak an option for a 37 pound sash. Did you ever have trouble keeping the windows open prior to the balances failing? For a 37 pound sash, a stamp of 2865 would work best. This covers a window sash in the weight range of 35 through 39 pounds. Take a look and let me know if you have any questions.