I have read through how to purge a zone, but I still have a question. I don't have individual drain valves on each zone. So I am unsure what the process would be in order to purge a zone. And to clarify, I do attach my hose to the drain on the return side?
yeah it would be better if each zone had a drain valve, but it's not necessary. Close all but one valve, get the system running (circulating), and open that one drain valve - slightly. With luck that'll force any air bubbles out. Close that zone and open one other; repeat.
I dunno if that will be as effective as having properly placed valves on each zone, but it's about all you can do here.