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Recently had a Aprilaire 700 humidifier installed by service technician that burned out after less than 1 year. New service technician informed me that the unit burned out because of being incorrectly wired. was told that the 24 volts from the humidifiers should not have been wired to 24 volts to the furnace. And should have only been wired to the humidistat As I have no background experience here I am Not sure if this was the case or not please comment
 

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The 110V side of the 24V transformer gets wired to the Neutral and the HUM connection on the furnace. One side of the 24V transformer goes to the humidistat, the return from the humidistat and the other side of the 24V transformer connect to the 2 wires on the humidifier. It does not connect to the 24V from the furnace at all.
 

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unless your furnace has a pc board with hum. terminals for a humidifer ,.....if not then it should be wired to a separate transfer circut
 

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yep carmon,hvac dude..see this all the time even when pc board has terminials they wire it through w-c not good to do lazyness.....but they are working..when we see this we change them add a transformer wire it through board... the right way...ben sr
 

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seen hundreds wired to w - c ... they work not saying its right way to do it...:eek:
Just out of curiousity, why is it bad to do this? I've read of people using this method but have never come across one. They're just using that terminal to run a 24 solenoid, correct?
 

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Just out of curiousity, why is it bad to do this? I've read of people using this method but have never come across one. They're just using that terminal to run a 24 solenoid, correct?
It will cause the thermostat to overshoot set point and overheat the conditioned space.
 

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Ive never had an inicdent where doing it this method was causing a problem , as long as the transformer on the pc board can handle the . v/a of it its ok ,,, thats right from the mfg of furnaces... but the correct way is to use its own power supply to the humidifer ,,,
 

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Ive never had an inicdent where doing it this method was causing a problem , as long as the transformer on the pc board can handle the . v/a of it its ok ,,, thats right from the mfg of furnaces... but the correct way is to use its own power supply to the humidifer ,,,
I suggest you do a little more in depth study on connecting to C and W.

No matter where you set the anticipator, the amp draw will be wrong for the setting and the length of the furnace run cycle will be affected.

All furnace install instructions dictate only dedicated terminals be used for humid hook up.
 

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sorry i shuda clarified .. this type of install is only usually done with electronic thermostats sry
Point taken....if you are using a s'tat that is battery powered only.

We like to use stats powered off the furnace power supply. And the last time I checked the furnace install instructions said "No external loads should be connected to terminal strip" because the solenoid of the humid causes a voltage drop that will cause erratic furnace operation.
 
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