constant force balance coil

Hello!

The issue you're having sounds like you might not have the appropriate coil weights. Can you weigh your sash and tell me the precise weight, along with the total number of coil springs in the window? Seeing your original pivot shoe would also be a huge help. I will do my best to assist from there.

Thank you!

Hmm, this is a bit odd. The 7.5 stamp on your spring indicates the spring weight so you were right about picking the S160-7. If you have one of these on each side of the window, that would total 15 pounds of support which should have been fine considering the actual weight is 14 pounds.

I'm not sure what to recommend without photos and I wonder if you have something different. Can you remove an undamaged pivot shoe and show us some photos? Can you also confirm the width of the coil spring band? 

Thank you for the photos! It appears you bought the right hardware so I'm not really sure what the issue could be. If the coil balances seem too weak then it's because they probably are. The problem you've been describing really only occurs when the springs aren't rated properly for the sash weight. I know that you've already checked the sash weight but you may want to re-weigh it just to be 200% sure. 

If your sash is 14 or even 15 pounds, (1) S160-7 7.5 pound spring on each side of the window should have been enough support. I'm not sure what the problem could be, I'm afraid. However, it is ultimately up to you if you wanted to use a higher spring weight but we can't make any guarantees, unfortunately. I am very sorry for the inconvenience. 

Hey there, Emily isn't here today but I will do my best to help.

Reading through your conversation it sounds like you're having trouble getting the right spring calibration for your window. To start, you don't want your coil springs to be either too heavy or too light. The way these work is that the tension of the springs is constantly pulling up on the sash, which is counter-balanced by the sash weight itself. If the springs are too weak then the gravity will pull the sash down and the window will be harder to open; too strong and the upward force will be too much, causing the window to be harder to close. In some extreme cases of the former, the window will even open up on its own.

All this is to say that if your sash is 14 pounds, then you need springs that carry 14 pounds. No more, no less. You do have a pound or so of wiggle room when it comes to coil balances but you don't want to go overboard. Stronger springs won't make the window work better; quite the opposite. 

More to the point, if the balances you purchased support 14 pounds but are still too weak, then the simple answer is that your sash is heavier than 14 pounds. What you're using is even stronger, with 15 pounds of support, so the fact that this system is still too weak tells me that your sash is probably even heavier than that.

You have two options ahead of you: reweigh your sash and take extra special care to get a precise weight, down to the ounce, without any shadow of a doubt. Or, you can take a chance on a heavier spring and hope it works better. That second option is a gamble, though, and there's no guarantee what will work or how well. There's even a risk that you'll run into the opposite problem and have a window that won't close.