window ballast

Question

Want to replace all my window ballast in my home but don't know the series. Windows are about 28 years old, Harcar windows. Stamped number on this window ballast says 2920? The metal length is 30"

Thanks, Ken

Removed another ballast that says 1720, the length is 18 inches

Bob · Accepted Answer

This looks like either a Series 380 or Series 385 Channel Balance. The only difference between these two balances is the depth of the bottom nylon shoe, so compare both with your old hardware to see what matches best. See the diagram below.

Comparison of the S380 and S385 balance shoes.