Bob from SWISCO responded:
October 21, 2019
Thanks for writing in. If one of your balances is stamped 3420 but is 28" long, that's pretty unusual. My guess it was cut down during installation to fit the window. Weigh the window sash to determine what stamp option you should select. See which range it fits below: Stamp Option Sash Weight Range 2710 5 to 9 lbs 2720 9 to 13 lbs 2730 13 to 19 lbs 2740 19 to 26 lbs 2750 26 to 30 lbs 2760 30 to 33 lbs 2765 33 to 36 lbs 2770 36 to 39 lbs *This information is based on 2 balances per sash. Balances are designed assuming friction in the jamb weather-strip will carry a portion of the sash weight. Suggested sash weights are approximate. |