Spiral Balance Springs of Unknown Origin

Question

These are a pair of balance springs I've taken out of a tilt-out single-hung unit. These are windows in a modular home of decent quality.

The aspect of these balance springs is that they have black tips instead of any of the colors I can find on the internets. This tells me that either there were no sizing standards when these were manufactured, or that they were manufactured at a location that didn't participate in the sizing standards.

I have found balance springs of seemingly the same size: 3/8" dia x 29" long. That's not the issue, I'm more concerned about making sure I get the right weight rating...

User submitted photos of a window balance.

Tom · Accepted Answer

If the diameter of the tube is 3/8" and this is for a tilt window, then you have our S900-29. These were never made with a black tip, though. I bet your color tip has just been discolored from grease and age. I recommend weighing your sash on a scale and referring to the chart we show on the S900-29 store page, that will let you know exactly what color tip would be best.