Series 170 Coil Balance Quote

Hey there. The stamps refer to the coil spring's weight capacity. It is the capacity just for that spring alone. You need to set up the right combination of coil springs so you're support half the window sash's weight on either side of the window, so that altogether the spring weights matches the overall weight. When there's no stamps on the springs you can weigh the window sash to figure out what to choose. The video below explains. See the second video that differentiates the Series 170 and Series 171 coil springs that work with the 15-192.

No, that would actually be quite bad for the window. If the springs are too strong, then the upward force they provide would be greater than the downward force provided by the weight of the sash. In other words, your window would be much harder to close, and would probably even open up on its own.

Since your springs have no stamps, then weighing your sash is your only option. This isn't something you want to guess.