Request replacement parts for window channel balance

Question

Hi. Just bought a house with old aluminum frame single pane glass dual hung non tilt windows and trying to repair them. The existing channel balances are are 26 inch long (including top and shoe) and 25 inch long for the metal frame. The larger windows are about 14 pounds and have balances that are stamped B.S.I. 24 B or B.S.I. 24 C. I also have a few smaller windows that are stamped 24 A. So I think that A is lower weight range, then B is more and C is more.

If you could tell me what the correct replacement part is that would be great. I think it is the S385 series from the photos, but it would be great to get your expert assessment and recommendation. I don't know who the window manufacturer is or even how old the windows are. I would guess they are likely 40+ years old? Thank you, Kevin

Bob · Accepted Answer

Thanks for posting. I agree, the Series 385 looks promising; the only other possibility would be the Series 380. The only difference between these two channel balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement. Compare the diagram below with your old balances to see which matches best.

Comparison of the S378, S380 and S385 balance shoes.

These balances should all have metal channel lengths of 25", so go with either the S380-25 or S385-25. Finally, you'll have to choose stamp options, which designate the strength of the balances. Your guess that the letters at the end of the old balance's stamps designated their strength is absolutely correct--the only difference in our stamp system is we use all numbers instead of letters, but it's easy enough to translate. For instance, for balances stamped 24C, go with our option of 2430; for 24B, use 2420, and for 24A, 2410. Let me know if you have any questions about this.

Finally, I can't tell who the manufacturer was either I'm afraid. These balances are used by a ton of different brands, so it's impossible to say based off them alone. That said, the good thing about brand-independent parts is it means there's always a chance of replacing them even if the old manufacturer went out of business--and that's the case here! Let me know if you ahve further questions.