coil balance

Question

# 3 on back
pat.# 6,983,513
# 5,371971

Bob · Accepted Answer

This looks like an older version of a Series 140 Coil Balance system. Now, if the '3' is on the coil spring itself, then you'd need an S140-3 3 lb system. If not, and you're uncertain what spring weight you need, obtain the exact weight of the window sash. You can then divide that weight in half, and that will tell you the spring weight you need for both sides of the sash.