window balance replacement

Question

I have 6 windows that all look a like. Most weight 28-29 pounds. One weights 37.5. The heavier one will not stay open. I checked the balances and they are good and so are the cams. I switched the heavier window out with one of the others. The lighter window working in both places the heavier won't stay open in either place. I have to believe that the heavier one (which has always had a problem staying open) has the wrong `balances. I believe that I need two 34" Series 385 Channel Balance
Product Code: S385-34. I have looked at the measurements and believe this is the correct balance with the correct length, weight range (from your chart) top and shoe. Would you please see the attached pictures and see if you agree. Thank you.

Jasmine · Accepted Answer

Thanks for writing in! For the heavier windows, if they are 37.5lbs then you'll need to select the 3365 stamp for a window weighing 35 to 39lbs. The 3340 can only support a window weighing 23 to 28lbs.

In regard to the balances, It looks like you have either the S380-34 with a 1" shoe or the S385-34 with a 1-3/32" shoe. The metal channel of these balances is 34". To determine which series is needed for your window, look over the dimensions from the diagram below to confirm the depth of your bottom shoe. Let me know if it does not match either measurement.

Comparison of the S378, S380 and S385 balance shoes.