Paul from SWISCO responded:
September 26, 2017
Your top balance fitting looks like our 19-002 and the bottom fitting looks like our 1-1/8" depth shoe 15-001, that makes a Series 390. The total length of your metal balance channel measures 37", so you would order S390-37 and the stamped spring weight number will be 3640. Let us know how you make out!
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Paul from SWISCO responded:
October 13, 2017
Awesome, glad to hear they worked out! Concerning your stamps, it really depends on the weight of the sash. You may want to weigh yours on a scale just to be sure. If the windows are all the same size, I'm not sure why the installers would use some that are 3650 and some that are 3640. It could be they ran out of one, and had to substitute with the others.
Now, will it be okay? Well, if you safely installed the 3640 on your other windows, and they work fine and everything's great, then you could get away with it. I would still recommend weighing your sashes just to be sure. It is possible to have a spring that is too strong. Think of it like Goldilocks' porridge: it can't be too weak, and it can't be too strong. You want it to be just right. |