Will S810-27 support a 30 pound window?

Thank you for posting! It would depend on which stamp option you select. The S810-27 has three stamp options, whose strengths are as follows:

26A: 4 through 8 pounds.
26B: 8 through 14 pounds.
26C: 14 through 20 pounds.

As you can see, none of the standard options for the S810-27 can support a sash weight of 30 pounds. Can you double check your sash weight to confirm that that is its weight? Also, are you sure that you have the Series 810 channel balance? It is a relatively skinny balance with a 3/8" width. If you aren't sure, please take a few pictures of the attachments on either end of the balance for me to identify, and confirm its channel width.

Please keep in mind that the weight range 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.

Based on the size of your metal channel, I do not believe that the Series 810 is the correct Series for you. In order for me to properly identify what Series you have, can you please upload a few pictures of the top and bottom nylon attachment? The stamp alone is not enough information to determine your Series; only the nylon attachments can help us figure that out.

In the meantime, you can take a look through our selection of 1/2" Wide Channel Balances for Non-Tilt Windows and see if you can find a Series that matches your attachment configuration.

Once we have your Series, we can help you figure out the proper stamp.

Actually, I believe that the 2650 option would be best for your window. It can support a window sash weight range of 26 through 30 pounds.

We do usually recommend replacing both balances at the same time. This will ensure that tension is equal on both sides of your window. Plus, you can always place the older, undamaged balance aside to use as a repair should another balance in the house go.