Paul,

   Re:

>     I removed the thermostat, but now I'm thinking that if I am successful
> in purging all of the air out of my system, it will all be for naught, as
> when I re-install my thermostat, I will loose a lot of coolant, and have to
> start all over with the purging.  

   Try drilling a 3/32" hole through the thermostat flange,
near the edge; install with the hole oriented at the top.  

   First benefit is no air gets trapped under the
thermostat.  Second is that the thermostat opens sooner.

Dale R.
COZY MkIV #1254