Easy humidifier wiring question


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Old 11-12-10, 07:34 AM
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Easy humidifier wiring question

Hello!

I have an Aprilaire 700 humidifier wired to a Carrier furnace with a hk42fz009 control board. Currently the humidifier is connected to the control board at Common and W, and works fine when heat is on. My question is this: Is there any way to wire it so it comes on with both heat and the fan? I know if I move it to Com and G, it will come on with the fan only (and not with heat). Can I just hook it up to the "hum" terminal (as shown in picture) and COM and have it work the way I want?

Thanks for the help.

JP

 
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Old 11-12-10, 11:29 AM
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why would you want the humidifier to run without heat. it wont do much good. but if your house is just so dry you could get a different humidifier, one the injects steam into the air instead of relying on the heat to evaporate the water that you currently have. but if u like what u have you can put it to common and g because the circuit board will power g once the fan starts in heat/cool/or just fan.
 
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Old 11-12-10, 12:39 PM
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Hi,

Thanks for the response.

I live in Colorado where it's super dry. I have hot water going into the humidifier which works fine with the fan. I have a thermostat that runs the fan intermittently to circulate the air, and I want the humidifier to run with that fan.

When I use it with COM and G, the humidifier then only runs with the fan and not with heat. Everything I've read has said that this is correct- G works with Cool and Fan only, W is heat only.

Thanks,
JP
 
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Old 11-12-10, 05:10 PM
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The G terminal is powered from the thermostat by placing the Auto-Fan-On switch in the On position or by having the thermostat activate when in the cooling mode. What this does is energize the fan relay which runs the fan at the cooling speed.

I assume that your humidifier runs on 24 volts AC since you have it connected to Com and W. Generally the HUM terminal will be 120 volts compared to the NEUT terminal (line voltage) and would be used with a line-voltage humidifier. This is NOT always true so testing with an AC voltmeter is in order. The HUM terminal may be energized with fan operation or it may be energized with only heat operation.

If you have a EAC (electronic air cleaner) terminal it will operate anytime the fan is running and will be 120 volts compared to NEUT.
 
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Old 11-12-10, 08:03 PM
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What model is your humidistat?
 
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Old 11-15-10, 10:29 AM
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Thanks for the help. Wired the EAC terminal to a 24v transformer and it works perfectly.

Thank you all again.
 
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Old 11-16-10, 08:49 AM
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Hooking up to the HUM terminal should give you what you are looking for. (Provided that the HUM terminal is 24v) The HUM terminals are energized when the HVAC unit is called on for action. Thus, allowing the humidifier to operate with a "G" and "W" call.

Make sure you are using hot water in the application. This will supplement as the heat source when running the fan.

Corey Brabender
 

Last edited by Gunguy45; 11-18-10 at 09:51 AM. Reason: Remove commercial link
 

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