channel balance option weight differences

Hi Tom! We actually have a weight chart on the S380-29 store page that tells you how much weight each option supports. You can usually use your old stamp as a reference, but if that's not possible then you should weigh your sash on a scale and refer to this chart to get an idea of what stamp is best for your particular application.

29" Series 380 Stamp Options are as follows:

• 2810 will carry a window sash weight range of 7 through 12 pounds.
• 2820 will carry 12 through 16 pounds.
• 2830 will carry 16 through 23 pounds.
• 2840 will carry 23 through 28 pounds.
• 2850 will carry 28 through 32 pounds.

No, we do not recommend using an option that supports either a lighter or heavier load than what your window is. These are precise systems and it's important to only get what you need. Anything stronger or weaker and the window will not work properly.

Weighing it on a scale is in fact the only way to know the weight of the sash. You won't find that information on a label anywhere on your window. 

Any common bathroom scale should be sufficient to this end.