Channel Balance for old windows

Question

I am trying to replace the channel balance on some old windows. I am unsure what spring strength i need.

I believe the items below are what I need. Can you verify this and tell from the stamped code what spring strength I need? A B or C

3 Window channels stamped with:
Stamp 8 28 B 3/8" width Channel / metal channel end to end is 29"
Product Code: S800-29

1 Window channel stamped with
Stamp 8 20 B 3/8" channel width / metal channel end to end is 21"
Product Code S800-21

Also I looks like i need these sash guides.
1/2 " top sash guide 18-036

Casey · Accepted Answer

It sounds like you may be on the right track. In order to determine the best spring option for your balances, you would need to weigh your sash on a scale and correspond that number to our sash weight range chart listed below the product description on the respective product page. If you would like our assistance in determining whether or not these balances are a match for your current ones, you may send us some photos of the balance for our review. That also goes for your top sash guide.