Tension springs

Hello there!

Thank you for reaching out to us. We may be able to help with this. I'll just need a bit more information to confirm. Can you show us a photo of the pivot shoe, preferably removed from the window? It being installed in the window track tends to obscure a lot of details. 

Thanks for getting back to us! I recommend our 15-177 pivot shoe which uses the Series 152 coil springs. The compatible coil spring housing is the 15-143 bushing, 15-144 bushing cap, and 15-145 support barrel. These parts "sandwich" around the coil spring. As for the pivot bar, see if the 26-316 matches up with your old one.

You have two options with a 25-pound sash. The first is to use two S152-6 6-pound springs on each side of the window. 12 pounds on each side will total 24 pounds of overall support. 

The second option is to use one S152-6 6-pound spring and one S152-7 7-pound spring on each side of the window. 13 pounds on each side will total 26 pounds of overall support. I know you said your window sash weighs 25 pounds, but either of these options should be fine as long as the coil weights total within a pound of the window sash weight.