Casey from SWISCO responded:
September 13, 2022
Hello, Past customers have been able to adapt the S500 spiral balance for older wood windows similar to yours. If this is a bottom sash, you would need to measure only the visible glass, not including the frame, and add 3" to determine the correct balance length. Once you know the length, you can follow the chart under the balance product description to choose the corresponding strength color for your sash weight. Thanks for posting! |