Seeking System Configuration Feedback

Stapler

I am redoing my 12-year-old system, mostly by changing out energy gulping zone pumps for zone valves and putting in a buffer tank. The rest of the system is already in place. Feedback from the Wall would be appreciated. Warning: small pdf file with the drawing is attached. You'll need Adobe Acrobat Reader to view it if you don't already have it. Thanks in advance.