Spiral Window Balance - HELP!

Question

I have several single hung wood windows that I am planning to use Swisco Spiral Window Balances on. They currently have different types of balances, so I do not have an old balance to measure. I do not plan to remove the sash from the window when I install the new Spiral Window Balancers.

My Sash is 20" total in height. Above this sash is a gap of 17 3/4" that the new Spiral Balance will be available during installation. How long of a Spiral Window Balance do you feel I should buy.

I am pretty certain that I need your S500 with your 17-012 Bracket.

Also, The weight of the sash is 9 lbs. Should I buy the Red or Blue?

The groove in the sash is for a 5/8" balancer.

Attached is a drawing of the window.

Your help is greatly appreciated. Also, Non Tilt.

Emily · Accepted Answer

Hello there!

The best way to determine the length isn't to use the overall height of the sash. That's a common misconception. Instead, you have to get the height of just the visible glass and then add 3" if it's for the bottom sash and 1" if it's for the top sash. For example, if the visible glass is 15" high for both sashes, then you want an 18" long balance (bottom sash) and 16" long balance (top sash).

Once we know the correct length, we can try and determine the proper weight option.