Impact springs for 45 LBS sash

Hello! Can you tell me the diameter of the white tube? Can you also tell me if there are any stamps printed on the tube itself? 

If there are no stamps, and if the tube is 9/16" in diameter, then I think you should be able to use our S600-22 as a replacement. The only issue is, these can only support 40 pounds maximum with its strongest rating. You should get the precise weight of the sash, down to the ounce, just to be 100% sure.

In that case, you should consider our S900-22 balance instead. As long as your tube is 3/8" then this should work well for you.

I'm sorry, I think I had a brain fart in my last response. I had told you that our S900-22 can work for you, since your tube was 3/8" in diameter. While that is true, the S900-22 absolutely cannot support 45 pounds. I had totally forgot that's how heavy your sash was from your first post. I'm very sorry about that! It's been a long week.

So, let me reset my response. If your balance tube is 3/8" in diameter, then I can guarantee your sash isn't 45 pounds. Conversely, if your sash is 45 pounds, then I can guarantee that your tube isn't 3/8" in diameter. No company ever made a balance that skinny that can support that kind of weight. It's not a matter of custom ordering a spring or anything, it's simply not possible. The balance is so skinny that it would buckle under the weight, no matter how strong the spring is.

In other words, one of those two details is incorrect. I would triple check both just to be 100% sure.