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· Registered
29 Posts
Discussion Starter · #1 ·
Hi. I am connecting a Aprilaire 600 humidifier to a Rheem Econet airhandler. The AH does not use conventional thermostat wiring, it uses only C, R and 2 communication wires to the proprietary Econet thermostat.

Documentation for the airhandler here:

On the wiring diagram you will see 2 connections for "HUM"

I found a thread on this forum previously that I cannot find today that stated the following (for a different Rheem AH):

Add a wire from R to one side of HUM.
One wire from humidifier solenoid valve goes to the other side of HUM.
The other wire from the humidifier solenoid valve goes to C.

Does the above advice hold true for this model air handler?

· Hvac Pro
25,117 Posts
It looks likely that when the tstat is demanding humidity it probably has a 24 volt supply at the HUM terminals. However you need to test it to make sure it is not 120 volts or find that info from Rheem in the install manual. Or you can put a meter there and demand humidity and if you get 24 volts AC it is good to use. Then you run one wire from Hum to your solenoid and the other Hum to the other wire of the solenoid and the tstat should control the humidity for you.

If the tstat does not have a humidity feature then you need to check when the heat AND fan is on to see if there is 24 volts and wire it thru a humidistat. If it is 120 volts then you need a step down 120/24 volt transformer.

The fan needs to be running with the heat on for the circuit board to energize the Hum.
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