The air won't remove all the water from your water heater. Bypass the heater and drain it using the drain plug, outside. Then leave the plug out. Afterward, with the heater bypassed, you can use compressed air to blow out all faucets. Start with the fsucets closest to the air supply and finish with the last (just the opposite of using antifreeze). And be sure to let the pump suck in some anti-freeze, as the air can't get to the pump because of the 1-way check valve at the pump outlet.
I advise using air, then sucking in anti-freeze through the whole system. That ensures you have water in all the drain traps and some in the holding tanks, too. The anti-freeze is only about $3/gallon and I only used two gallons for my 32RLDS. Pretty cheap insurance.
2015 Jay Flight 32RLDS Elite
2012 Chevy 2500HD Crew Cab LTZ (6.6L Duramax/Allison)
Equalizer Hitch (1200# bars)