11 Year Old SIlverline 2900 Series Single Hung Window Balances

Question

I had a new home in Bluffton, SC which has Silverline 2900 Series single hung windows of various sizes. Due the heat and humidity these windows are very rarely opened except for cleaning maybe once a year.

Several windows have had (what I call) the balances release and the balances are now at the top of the window. Of course the tilt latches have broken.

There are no visible marking on the balances so I'll use your window measurement and weight to ID the appropriate balance.

However, the windows still have the bottom pivot similar to your series 795 balances on both sides. I am surprised that the balance has separated rather than having the spring corrode.

Can you help me here?

I am an engineer having built and rebuilt cars, room additions and repaired or replaced most of what needs repairing or replacement. But it surprised me when I heard a balance "break" and is now at the top of a closed window. Inspection revealed this on the 3 windows seldom opened on the sunny side of the house.

Tom · Accepted Answer

I'm not sure what the issue may be. If you have a balance like our Series 795, then it's possible that the hook on the shoe that clips over the rivet (see the video below for an idea of what I mean) snapped.

That said, it is also odd to me that the shoe would fail before the balances. It's not unheard of, it certainly happens, but it's not common.

One explanation would be that your springs aren't the proper calibration for your sash weight. If the balances aren't balancing, then there could be undue strain to that exact part of the shoe. It would be forced to withstand either more weight from a heavy sash or more pressure from a too-strong spring. To confirm this, please give me the exact weight of your sash and the stamp printed on the balance's metal channel. That will let me calculate whether or not your spring strength is right for the job.

Then again, all of what I just said is just a hypothesis. It's also possible that the plastic is poor quality and it broke because it was 11 years old. I think I'll need more data before I can say for sure. Once you get me that sash weight and stamp, I'll be in a better position to make a judgement. Photos of the hardware in question would also help. Let me know!