There are multiple ways to perform a de humidification process with an air conditioning system. Number one there is the ability to change the fan speed to increase the ability of the system to collect more moisture out of the air. Basically, a D humidification, standalone system is a very small air conditioner only it doesn’t blow air into the room what it does is create a very cold coil to condense the moisture blown slowly over that coil and allow it to drip into a collection tank. With a whole house, air conditioner, we can perform the same function by slowing down the blower speed and allowing the air to stay in contact with the coil longer thus removing more moisture. This is very common approach in the tropical areas of safe Florida now with a nest thermostat is wired with a D humidification function. It can be one of two things. It can signal the control board in the air handler to switch to low speed fan, or it can turn on a standalone dehumidifier.
The humidification system is only going to be activated when the gas furnace is turned on. Since your humidifier has a standalone humidistat, all the thermostat will do a signal dehumidifier to turn on all the control of humidity and the run will be done by the actual Aprilaire 550.
The AC Cooling Wizard
NestPro, Google Pro, Mechanical Engineer and HVAC service company owner.
If my answer solved your problem, click Recommend this Answer below, and If it helped you, please give a Kudo.
