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Balance ID

A home owner from USA says:
I need to replace the channel balances on a sliding (non-tilt) window but I have some questions:

First, It is a very old building and I'm not sure the ones that were previously installed were correct in the first place (exactly correct model, length, etc). Is there a way to determine the exact correct balances I need just from the window itself? I'm including several pictures

I'm guessing the ones that were previously installed were way too long and probably at the wrong tension. The glass part of the window is 27 inches. The original balances were 32 inches. I did my best to replace them about 2 years ago with 29 inch balances and those just broke as well. Not even sure if they had the correct tops and shoes.

Also, each side of the window frame seems to each have 2 possible positions (side by side) for each balance. How do I know which one to use? Am I supposed to use both?

This is the second time my balances have broken within a year. The strings inside keep breaking. Is that from too much tension? Too much weight? Any help would be appreciated.

Attached are pictures of the tops and shoes of the current balances I'm replacing, but as I said these may not have been right in the first place. Also attaching pix of the window frame (with the 2 possible channel positions) and the side of the window itself which hopefully will help determine the correct replacements.

Width of previous balances were 1/2". Length was originally 32", then 29". Actual glass length of window is 27". Stamp number on the older 32" ones is 3240H. Stamp number on the newer 29" ones is 29400C.

Thank you for any help.
A quick learner from Brooklyn, NY says:
A little more info about this issue along with pictures:

The window never seemed to open and close smoothly, even from the beginning. It was also hard to keep down which I assume is because there was too much tension.

I'm guessing the balances that were previously installed were way too long and probably at the wrong tension. The glass part of the window is 27 inches. The original balances were 32 inches. I did my best to replace them about 2 years ago with 29 inch balances and those just broke as well. Not even sure if they had the correct tops and shoes.

Attached are pictures of the tops and shoes of the current balances I'm replacing, but as I said these may not have been right in the first place. (I do realize the hook is bent way out of shape in the picture) Also attaching pix of the window frame (with the 2 possible channel positions) and the side of the window itself which hopefully will help determine the correct replacements.

Width of previous balances were 1/2". Length was originally 32", then 29". Actual glass length of window is 27". Stamp number on the older 32" ones is 3240H. Stamp number on the newer 29" ones is 29400C.

Thank you for any help.
User submitted photos of a window balance.
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Paul from SWISCO responded:
Hmm... this is a tough one. It looks like your window was originally made to accommodate two balances on each side. Ideally, you wouldn't just use one position, you'd use both at once. This isn't very common, though, and without seeing what was originally installed it would be very hard to determine what you need exactly.

That said, we may still be able to help.

You might be able to use just one balance on each side. Based on your glass height, I think a 28" long balance would be best. Looking at your attachments, I think you should consider our Series 390 channel balance. So that gives us an S390-28.

You just need to determine what option you need. This is a crucial step, and it may be why the balances have been failing up until now. Remove the sash from the window and place it on a scale to determine the weight and match that up with the options shown for our S390-28.

Hopefully, that will be enough, but it's hard to be confident about it. These windows are weird and, like I said, not all that common. I think this is the best place to start, though.

Oh, and before I forget: your top sash guide looks a lot like our 18-057. Carefully compare its dimensions to yours and see how they match up.
A quick learner from Brooklyn, NY says:
That is extremely helpful! Thank you! So here are my follow up questions:

It looks like you got all the part numbers correct, thank you. Would you recommend replacing the top sash guides? It looks like mine are a bit worn.

Also, it seems that the 18-057 is fairly wide compared to other top sash guides also used with the 390 series. Is it possible that the 18-057 is made to accommodate 2 balances on each side? Would that work? Or do you think an incorrect sash was previously used to replace the original window? Is it possible that the window (and top sash guides) are meant to accommodate two 3/8" balances on each side instead of one 1/2" balance?

And if I do use 2 on each side, would that mean I need to cut the weight range in half when determining the tension option? Since I would then be doubling the support on each side?

And if I do only use only one on each side, I guess I'll have to just use my best guess as to which position to put them in, unless you have any advice on that.

Thank you again for your fast, thorough, and knowledgeable response. It's so nice that you take care of your customers so well.
A quick learner from Brooklyn, NY says:
And just a couple more quick thoughts:

If I did try to use two 3/8" balances on each side it looks like the series 800 might work?

And I'm wondering what the difference is between the 351 and 390 series (which is basically asking the difference between the 15-002 and 15-001 shoes). Other than the color of the shoe they look exactly the same. Just curious.
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Paul from SWISCO responded:
I don't know if the 3/8" balances will work for you. They may not be strong enough. Based on your old hardware, I would stick with the 1/2" non-tilt window channel balances.

It's possible the 18-057 was meant to work with two balances, but if your window has been using one balance on each side with the 18-057, then I think that it should be okay this time around. Again, though, I don't have a lot of experience with these windows so I can't guarantee it.

You are correct, the difference between those Series is between the shoes, specifically their depth. Check out the diagram below.
Comparison of <a href=15-001 & 15-002' />
A quick learner from Brooklyn, NY says:
Ok, I just purchased from you 2 of the 18-057's and 2 of the S390-28 with weight code 2740 (the sash weighs 22 lbs). We'll see how it all turns out. Thank you for all of your help!
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