Mismatched balances

Question

I am repairing a single hung window. I removed the channel balances, and they are not the same. No wonder why it broke. A single spring on a wide window is less than adequate in my mind. I would have preferred two springs, one on each side, I presume they should be weaker springs since there are two of them. My window sash is 52 inches wide & weighs about 25 lbs. But, I cannot figure out what series, (380 385, etc) I have. Presume it has to do with the size of the channel but I don't know. Judging by the markings I can see, I have 2940 EL and a 2950 BS balances. I prefer to get two of the same, unless you recommend otherwise. Please advise.

Casey · Accepted Answer

Hello,

It looks like you may need our Series 377 channel balance. There should be identical balances on both sides of the window.

I would recommend that you weight the window sash to see which would work better for both replacement balances:

2940- 23 to 28 lbs

2950- 28 to 32 lbs

This information is based on 2 balances per sash. Balances are designed assuming friction in the jamb weather-strip will carry a portion of the sash weight. Take a look at the specifications on our S377-30 product page to determine what will work best for your window. Thank you!