Boiler with 2 zones and 2 iar handlers

Good Morning. Let me start off by saying I might use the wrong terminology here as I am new to HVAC, but am fairly mechanical. I just replaced a ductless system in my home with 2 separate ducted systems. One for upstairs, one for downstairs. I was able to wire up the air conditioning no problem and it worked great all year, now I am getting ready to hook up the heat and I have a few questions. With the old ductless system, my boiler received the signal from the thermostats, and turned on the circulators, and sent the hot water to small Honeywell Zone valves that opened and sent that water to the unit that was calling for it. Now that I am changed over to forced air, Im assuming I need a new set of controls for this. I have done some research on zoning and the controls needed for that, and see that I can get a Taco boiler control that will handle 3 zones. That seems pretty straight forward, my question is, what tells the air handler to come on? Do I need another control for the air handler (Hydro Air Control)? Or is there something is the regular boiler control or zone valve that will tell the air handler to come on? Thanks in advance for your help. Brian