Hello I would like to hook up my desert spring rotary disc humidifier to my new carrier infinity model #59MN7 furnace. I see the control board in the furnace has a HUM (humidifier) terminal and a 24VAC screw terminal. Is it really that simply or am I missing something? I have the carrier infinity touch control thermostat hooked up to it. any help would be appreciated.

1 Answer 1


According to the documentation for your unit.

The HUM terminal is a 24 VAC output, energized when the blower is operating during a call for heat.

Connect an accessory 24 VAC, 0.5 amp. maximum humidifier (if used) to the ¼ in. male quick-connect HUM terminal and COM-24V screw terminal on the control board thermostat strip.

NOTE: If the humidifier has its own 24 VAC power supply, an isolation relay may be required. Connect the 24 VAC coil of the isolation relay to the HUM and COM/24V screw terminal on the control board thermostat strip. (See Fig. 32.)

Figure 32.

So if the humidifier is less than 0.5 amperes, then you can simply use the HUM and COM terminals. Otherwise you'll need an alternate power supply, and an isolation relay.

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