AC and hydronic coil and humidifier

Nick_R

I am looking for advice on adding a controller to my heating system. I will try to provide as much detail as I can without going overboard.



My two story home has retrofit central air with the duct work in the attic, and the thermostat for the AC on the second floor. I installed radiant floor heat on the first floor and a hydronic coil in the AC plenum. The hydronic system has a controller for the three pumps located in the basement. The thermostat for the floor heat is on the first floor.

Since the AC system wasn't originally installed with an option for heat the wiring was very simple. There was just a two lead wire running to the second floor thermostat. I replaced this with an eight lead wire just incase I wanted to add other features later. I added a relay to the wiring on the AC. Now when I want heat I shut off the breaker to the outdoor condenser and switch the thermostat to heat. A wire connected to the relay runs downstairs to the pump controller sending up hot water to the coil.

This system works fine with the exception of having to switch off the breaker to the AC condenser. I would now like to add a whole house humidifier. I chose an Aprilaire 700 with the digital humidistat. After looking at the installation manual I realize that I am going to have to add some sort of furnace control board to get all the functionality out of the humidifier.

Can anyone recommend a universal HVAC controller that would work in a system like this? I have looked at some boards online but I can't tell if they are meant to run just a furnace or a furnace AC combo. I see a lot of specs regarding flame control and fan timers. I am not sure if I can bypass these. Any advice would be greatly appreciated. If I can't find a universal board I might do a PLC.