Greetings,
I used a 1/2" valve because the area of a 1/2" circle is the same as the sum of the area of four 1/4" circles. In may case, I read 11 in/Hg with all motors running, all the zones valves closed, and the with the bleeder valve closed. When I open the bleeder valve all the way I read 10 in/Hg. If my part/sheet hold down is leaking and I read 10 in/Hg then I don't open the valve because I figure the motors are getting a little air which appears to be a loss of 1 in/Hg. Not very scientific, but it seems to work for me.
Kind regards,
JIM
