Window balance size

Question

I came to order a new window balance as one of mine is broken but I'm not sure the right size. My existing balance appears to 20.5 inches long with a tube diameter of about 0.5 inches. There was a pic tube which has rotted away of an unknown diameter over the spring.  What do I need to replace this?

Bob · Accepted Answer

Thanks for posting. For a spiral balance that has a length ending in a X-1/2" increment, simply round up--so in your case, go with 21". Is the outer tube that has mostly broken away 5/8" in diameter? If so, go with a S600-21. Let me know if that diameter doesn't seem right. Let me know if you have further questions.