Coil Balance Assistance

Hey Danielle. This is a coil balance system. Specifically, it looks like you have our 15-180 Pivot Shoe, which uses Series 190 Coil Balances. To know what spring weights you need, look for stamp codes on the springs. If there are none or you are uncertain, give us the exact weight of your window sash and we'll work out what you need.

The window sash is the movable part of the window with the glass. You can remove it from the window frame and gently place it on a bathroom scale to obtain the exact weight. From there, we can tell you exactly what coil balances you need.

If the window weighs exactly 15 lbs, I would use one of the S190-740 7 lb springs on each side of the sash. This would equal 14 lbs of support total--being within 1 lb of the actual sash weight should be fine. If, of course, the window weighs more than 15 lbs and is closer to 16 lbs, it would be better to use the S190-840 8 lb springs on both sides. Be sure to try and get an exact measurement. Since you're using just one coil on each side of the sash in this case, you could use our 15-186 Clip and 15-182 Bushing for both coils. 

The the S190-740 7 lb spring on each side of the sash should work perfectly. 

Hey Danielle. If it's just one window that weighs exactly or a little less than 15 lbs, then you actually just need (2) of the S190-740 7 lb springs. You're going to install one on each side of the sash, for a total of 14 lbs of support (this is close enough to the actual weight, as explained earlier). Therefore you'd also just need (2) of the 15-186 Clips and (2) of the 15-182 Bushings. Also, if your original pivot shoes are undamaged you can reuse them; but otherwise, you'd need a pair of the 15-180 as well. 

I know originally your window had a pair of coils on each side of the sash--this doesn't really matter. Coil balance spring weights have changed over the years, with stronger or weaker spring variations being made. You probably originally had 3 lb and 4 lb springs on both sides of the sash; that amounts to the same thing as a single 7 lb spring on both sides. It really doesn't matter how many springs you use; all that matters is matching that window sash weight with an even amount of support on both sides of the sash. Also, it doesn't hurt that a single spring system is a lot easier to install! Let me know if this all makes sense.