coil spring not strong enough

Question

After this new coil spring (9 lbs series 180) was installed the window will not remain in the open (up) position, although it is much easier to lift after it was installed.

Lauren · Accepted Answer

Hello, thank you for posting,

It sounds like the spring may be the incorrect weight rating.

To further review, are you able to show us the original coil balance assembly and how many coils it used? Was there any numbers stamped on the coil or nylon housing? Please also provide the weight of the window sash. The sash will need to be removed and placed on a bathroom scale. Thank you!