Follow up

Thanks for posting. Sorry to hear that these balances didn't work. See our Return Policy here. If these were not the correct balances, then I'm afraid going off of them won't be very useful in determining what you actually need. If the original balances are missing, it's going to be difficult to determine what you need, but maybe not impossible. We'll need to go back to the beginning.  

• First, are there any windows at all in the house that are the same or similar in size and design, and with the balances still in the window? If so, can you remove them and show us pictures of their end fittings, or attachments? That's crucial. Without that it's going to be next to impossible to figure out what balance Series you need. 
• Please tell us the height of visible glass in the window. The balances you need will be 1" longer than this length. So for instance, if the windows have a visible glass height of 13", you'll need 14" long balances. 
• Finally, if you haven't done this already, weigh the window sash to obtain the exact sash weight. That will let us choose the right stamp option. 

From there we'll do our best to see if we can find exactly what you need. Many thanks. 

If you don't have an original balance to use as a reference then this project will be very difficult. The only thing I'll be able to tell you for sure is the size and strength of the balance. The Series (which is what we call the configuration of nylon fittings) will be completely unknown and won't be possible for us to guess.

That aside, if your visible glass is 15" tall then you should get a 16" long balance. This is 3" longer than the 13" balance you bought, so that's something to keep in mind.

I still need the exact weight of the sash in order to tell you which stamp option to go with. The Series, as I mentioned, is a complete unknown and it won't be possible for me to advise on that.

Sure thing, I totally understand. I'll be here to help whenever you can get that.

Great, thank you! With a visible glass height of 16" then a 17" long channel balance is what the installers would usually put in there. For a 13.7 pound sash, that means you also want a 1630 stamp option: two balances with this stamp carry 12 through 14 pounds.

That only leaves you with a question of what Series to go with, which is unfortunately not something we can help with. That requires the old balance as a reference point. Without that, we have no basis with which to identify. I am sorry for the inconvenience.