Dual Coil

Thank you for your patience during this busy season. Can you tell me the thickness of your springs? Can you also show me the pivot shoe to which they attach? Thank you!

I agree, that looks like our 15-111. If you look in the product description, you can see we recommend the Series 160 spring, which just so happens to be 1/2" thick. I think this is what you need.

Now for the stamps. You mentioned one is marked "7" but the other isn't marked anything. I think it's safe to say that your "7" spring could be replaced by our S160-7, but I'm not sure about the other one. Was this stacked on top of the 7, or was it just installed on the other side of the sash? It looks like it was stacked. You should probably weigh your sash to determine the best match.

Here's how we calculate weight. Unlike other balances, when it comes to coil balances you want to divide the weight of the sash between each spring. Since you're using four balances altogether, you'd divide the sash weight by 4. 

There is a chance that your blank spring is also a 7, but I personally wouldn't bet on it. If you have  two 7.5 pound springs on each side of the sash, it will be 30 pounds (give or take). If that's the case then using four S160-7 springs is your best bet.

If your sash is a different weight, though, then it's okay to mix and match springs as long as the two pairs are identical. For example, you could use a 3.5 pound spring and 4.5 pound spring on each side, but you couldn't use a 3.5 and 4.5 on one side and then a 7.5 and 5.5 on the other. I hope that makes sense.

If you're not sure what to do, just let me know the weight of your sash and we will calculate it for you.