Can I run my hydronic circulator off an appliance cord in order to use it to purge air?
For those who are interested in doing this:, I simplified the wiring diagram as illustrated below.

I cut the 120v lead to the circulator relay and wired it to a terminal block.  From that terminal block, leads go to to one pole of a 3-way switch and to the relay. Likewise, the other side of the relay was cut and now goes to the other pole of the switch.  The center pole of the switch goes to the circulator motor.   This allows me to run the circulator without running the furnace.  Total cost was less than $10.