What Is 24V Hum

Step 4: Connect the 24-volt wire from the humidistat to the furnace. On the control, there will be a terminal labeled HUM (humidifier) for the wire connection. … The terminals on the humidistat will be labeled AA for easy identification and connection.

What does hum mean on a furnace control board?

Step 4: Connect the 24-volt wire from the humidistat to the furnace. On the control, there will be a terminal labeled HUM (humidifier) for the wire connection. … The terminals on the humidistat will be labeled AA for easy identification and connection.

What does 24V common mean?

The C wire is simply the “common” side of the transformer 24V output (there are two wires coming out of the 24V transformer, “hot” and “common”). Just tap into the “common”. The R (red) wire is really the power source. The C wire closes the circuit and allows continuous flow of 24V energy to power the thermostat.