Coradco balance, S751?

A handy person from NJ says:
May 20, 2012
I have older Coradco windows that drop so I'm looking to replace the balances. The only marking/number I can find is 20, I've attached a picture. The knife lock shoes are the same as your 15-014's.

I pulled the balance out. It is identical to the S751 ribbed series. It is 21" long so I assume I order the 21" S751? I see three parts listed: 20TG, 20HD, 20R, what is the difference? I'm kind of curious why the part number starts with 20 for a 21" balance.
A user submited photo of window channel balance
Profile picture of Paul
Paul from SWISCO responded:
May 30, 2012
Thanks for posting! For many channel balances, the first two numbers of the stamp are one digit less than its length. There are exceptions of course, but traditionally that is the case. A stamp of 20 on a 21" Series 751 balance makes sense. However, do you have any other letters or markings on your stamp? Does it only say 20?

If there are no other markings, we will need to know the weight of your sash. This will help us determine the appropriate option for you to select.

Also, you may want to look at our 19-030 Long S-clip. That looks like it may match your top clip.
A handy person from NJ says:
May 30, 2012
Hi Paul - There are no other markings on the balance, only the 20. Is there a way to determine the sash weight other than the obvious which is to take it out and weigh it? This is a double pain, wood framed sash roughly 30x22.
Profile picture of Paul
Paul from SWISCO responded:
May 30, 2012
Unfortunately, the only way to determine your sash weight is to remove it from your window and weight it on a scale.
A quick learner from NJ says:
June 17, 2012
I finally got the sash weighed. Each sash is 14 pounds. Thanks
Profile picture of Paul
Paul from SWISCO responded:
June 18, 2012
Thanks for getting back to us! I recommend that you select the 20R stamp option. Two S751-21 channel balances with the 20R stamp option can carry a window sash weight of 10 through and including 17 pounds.

Please keep in mind that the weight range capacity 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.
A handy person from NJ says:
June 25, 2012
Success! Four channel balances replaced and the sashes are functioning as they should. One install note that should be pointed out as a supplement to the install video, the knife lock points need to be pointing inward to function properly. I made the mistake and then corrected. Thanks for all of your help.
Profile picture of Paul
Paul from SWISCO responded:
June 25, 2012
Great news! I'm glad everything worked out.
Balance knife lock Shoe
Balance knife lock Shoe
15-014
$1.09
Long S-Clip
Long S-Clip
19-030
$0.70
21" Series 751 Channel Balance
21" Series 751 Channel Balance
S751-21
$10.56
How to install a ribbed tilt channel balance with knife lock shoe
How to install a ribbed tilt channel balance with knife lock shoe
VIDEO
WATCH >
Classifying Channel Balance Fittings
Classifying Channel Balance Fittings
GUIDE
READ >
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)
Current wait time is 3-4 business days
We promise that one of our experts will personally get back to you as soon as they are able. Thank you very much for your patience and understanding. If your inquiry is time-sensitive, please feel free to reach us at (888) 991-1929 or at help@swisco.com.