Window replacement balance

Thanks for contacting us. Your old balance looks like a match for our S395-30. Your stamp, 2940, indicates that a pair of them can carry 23 through 28 pounds.

Your mentioned that your sash is 28 pounds, so 2940 is appropriate. If this spring were too weak then your window would be hard to open, but you wouldn't have any issues closing it; indeed, your window would probably shut of its own accord. If it were too strong, you'd have the opposite problem.

You could consider going up to the 2950 option (28 through 32 pounds). The window would theoretically be easier to open, but since they're both rated for 28 pounds I don't think you'll see much of a difference.

Assuming the tracks are cleaned and lubricated, there isn't much else that would make your windows harder to open and close. I would triple check the precise weight of your sash to be sure that it really is 28 pounds exactly. A difference in ounces one way or the other could make a significant impact on how they operate.

Yes, when I say that the 2940 stamp is rated for 28 pounds, it's under the assumption that two balances are carrying the load. Channel balances like are only meant to work in pairs. You don't want to divide the weight in half at all.

If the window works fine after the one balance broke, then odds are the bad balance was your only issue. Its spring probably just got stiff with age, or maybe it was a little corroded. It happens.

Regardless, you definitely don't want to use only one balance on your window. It may work now, but that won't last forever. 

I think it'll be fine. If your current shoe is 1-1/16", then odds are it was 1-1/8" deep originally and wore down a little over time due to friction. This is a very common occurrence. 

If those windows are identical to the one you just repaired then you should be ok with that type of balance series. If not, you would want to remove one of the balances and send us another photo, with the metal length measurement, and stamping on it do that we can take a look and see if the Series 390 would work just the same or if another one needs to be recommended.

Are you certain the window weighed exactly 28 lbs? If the window was in fact lighter than this, then this would explain the resistance being able to close the windows, in which case a lower stamp option might be preferred. You said youv'e always had trouble opening and lowering the window; did you specifically always have trouble keeping it closed? If so, this would confirm you might need a lower stamp option. If you could confirm the exact weight of your window sash, perhaps on a bathroom scale, we'll do our best to find the right solution.