There should be just above your zone valves a tee with a hose bibb connection AND a Gate valve if your plumber had any consideration.
There should also be a a tee with a hose bibb and a shut off just below that. Now what your suppose to be able to do is put your zone valve on manual operation isolate all the other zones and use the fast fill device on your automatic feeder and connect a hose to the RETURN line.
Increase the pressure to about 28 PSI ( acutaly now would be a perfect time to test the peration of your relief valve @ 30#) as the fresh water flows out it will push out the air trapped in bends or other installation defects..
SylvanLMP