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    sierra's Avatar
    sierra Posts: 1, Reputation: 1
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    #1

    Nov 12, 2005, 02:38 PM
    Humidifier installation
    Got a new Cleanaire humidifier with 24 volts input and have problem to find 24 volts feed from furnace. Is there any way to get 24 volt from furnace without using 120 to 24 volts transformer. Thanks in advance. :confused:
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
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    #2

    Nov 12, 2005, 04:44 PM
    The humidifier surely was meant to run off the 24 volt transformer in the furnace. Most furnaces have an R and a B or C contacts connected directly to the transformer. If you want it to only run when the blower is running, that means tracking down the coil of the relay that runs the blower. Chances are on a newer furnace it is on a circuit board and may be 12 volts DC. The relay in turn may be controlled by a limit switch which may be either the 24 or 12 volts. If it is the 24 volts, you could wire the humidifier to where it returns to the circuit board and the B or C terminal. If the limit switch is 12 volts too, you can still use its contact, but must add a 12 volt relay to switch a wire from the R contact.

    If you need to, post back with what you have and I can give more details. Do the instructions for the humidifier say anything about having the blower control it?
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
    Uber Member
    		  
    #3

    Nov 12, 2005, 04:45 PM
    The humidifier surely was meant to run off the 24 volt transformer in the furnace. Most furnaces have an R and a B or C contacts connected directly to the transformer. If you want it to only run when the blower is running, that means tracking down the coil of the relay that runs the blower. Chances are on a newer furnace it is on a circuit board and may be 12 volts DC. The relay in turn may be controlled by a limit switch which may be either the 24 or 12 volts. If it is the 24 volts, you could wire the humidifier to where it returns to the circuit board and the B or C terminal. If the limit switch is 12 volts too, you can still use its contact, but must add a 12 volt relay to switch a wire from the R contact.

    If you need to, post back with what you have and I can give more details. Some furnaces have an auxiliary contact to run a humidifier. Do the instructions for the humidifier say anything about having the blower control it?
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