Replacement needed for dual coil balance

Question

the only marking is a 5 on the top coil and a 6 on the bottom coil. 12 of these need to be replaced in 6 windows. Do you have the assembled unit available?
The window weight is 20lbs, the window length is 29".
Coil thickness is 0.510".
The overall length of the plastic piece with the 2 mounting holes is 3.30", the major width is 0.775", the minor width is 0.475".
The thickness of the lower plastic piece is 0.530", the overall length is 1.945", the major width is 1.260", the minor width is 0.875".
The window supplier is unknown.

Emily · Accepted Answer

Hi there!

Our 15-180 appears to match what you have here. The numbers stamped on the spring indicate the weight so a 5 and 6-pound spring on each side would total 22 pounds of overall support. If you found that these worked well, you can stick to what you have now or switch to (2) S190-540 5-pound springs on each side to support a 20-pound sash.

Let us know if you have any questions!