# Humidifier wiring



## sgw1064 (Oct 27, 2010)

i installed a humidifier on my furnace the water supply has a float switch humidifier has a motor for a water pad and the i would like the 24volt motor to just run when the furnace is on. can i hook this motor to the wires coming from the house thermostat


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## kok328 (Oct 27, 2010)

You can do it that way or you can install a humidistat to control the humidifier.  This way you don't pump too much humidity into the home.


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## sgw1064 (Oct 27, 2010)

Thanks kok i was planning on installing a humidistat but what i was wondering is if i can use the 24 volt wiring from the thermostat instead of installing another transformer. Nothing is marked in the furnace but i can see the thermostat wiring. I am trying to just have the humidifier motor running when the furnace is on


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## paul52446m (Oct 27, 2010)

The reason they send a transformer with humidifier is, a lot of furnaces have a transformer just large enough to run the furnace. Does your furnace have a electronic board on it? If it does you should have two post marked HUM.
 This HUM posts are only hot when the blower is going on the furnace.
 What you have to be careful of is check to see what the voltage is on the Hum
 post when the blower is on. Some are 110 volts so you use your transformer that came with the humidifier. other are 24 volts so you can use it with out the transformer.  Later Paul


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## kok328 (Oct 27, 2010)

Oh, wait a minute sgw, "Humidifier motor"?  If this the rotating wheel style humidifier then heed paul's advice.  I was thinking that you were just looking to power the water line solenoid.
I recently installed a motorized damper on my combustion air intake vent and knew that the control/thermostat transformer wasn't rated for that, so I tied the damper into the humidifier transformer.  To prevent over humidification, I simply turn off the water supply at the saddle tap until later in the season when I need humidification with every heat cycle.


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## sgw1064 (Oct 27, 2010)

Thanks guys. Yes it does have rotating wheel. I understand how to wire in the transformer and humidistat but the furnace is a 25 year old with nothing marked and does not have an electronic board. I am unsure where to wire in this rotating wheel motor so it turns when the furnace is on.


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## paul52446m (Oct 27, 2010)

sgw1064 said:


> Thanks guys. Yes it does have rotating wheel. I understand how to wire in the transformer and humidistat but the furnace is a 25 year old with nothing marked and does not have an electronic board. I am unsure where to wire in this rotating wheel motor so it turns when the furnace is on.



On the old units we used a sail switch So when the blower came on it made the sail switch for your 24 volt power and we would just wire the transformer into the line voltage. Are you using just one speed on your blower? If so you can hot up your transformer by wiring it up to the blower hot line, after the fan switch.
  Later Paul


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## sgw1064 (Oct 27, 2010)

Thanks Paul. I will try to find the motor hot line and wire in there


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## paul52446m (Oct 27, 2010)

Just find your fan switch you have a hot line going to it and one wire going
 to the blower, that the one you tie into.  Later paul


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## sgw1064 (Oct 28, 2010)

Thanks Paul


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