Aprilaire 600 to Luxaire Furnace - Wiring Questions

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Old 01-09-19, 07:11 PM
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Question Aprilaire 600 to Luxaire Furnace - Wiring Questions

Hi there

I'm in the middle of installing an Aprilaire 600 (automatic version), but the only part of it I'm having trouble understanding is the wiring instructions.

Based on the following wiring diagram, and the following labeled picture of my furnace's control board, can someone please tell me exactly how to wire this thing up?

My furnace has a "HUM" terminal on the board, so does that mean I can wire the G wire between the furnace HUM to the humidistat G and skip wiring my [Nest] thermostat G to the furnace G as it shows in the wiring diagram? If so, could low voltage wiring be used here, or a thicker gauge wire like some of the other terminals near the HUM terminal on the furnace?

Would also appreciate if someone can clue me in, where on each of the wires in the wiring diagram one should use low voltage wire versus thicker gauge wire.

Much appreciated!



 
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  #2  
Old 01-09-19, 07:51 PM
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Ignore that HUM terminal as it is 120vac which would fry the humidifier, controls, and thermostat. Follow the wiring diagram you have.
All of those wires on the diagram are low voltage (24vac). The only exception is the other side of the transformer where you hook to 120vac.
 
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Old 01-09-19, 11:25 PM
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Are you wanting the nest to control the humidifier ?

If no..... follow my easier to follow diagram. It takes power from the furnace. It does not allow the humidistat to turn the blower on. The humidifier only runs when the heat is running.

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Old 01-10-19, 11:29 AM
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Originally Posted by PJmax View Post
Are you wanting the nest to control the humidifier ?

If no..... follow my easier to follow diagram. It takes power from the furnace. It does not allow the humidistat to turn the blower on. The humidifier only runs when the heat is running.

Attachment 100324
No, don't necessarily want/need the Nest to control the humidifier (one less wire to fish down the wall), but is there a benefit to doing so? I assume not as long as the humidifier is only turning on when the fan/blower is on, but let me know. FYI my furnace runs the fan/blower for a few minutes longer once the gas flames turn off, since there's residual heat to pump out.

Thanks for sharing your diagram!

Astuff, what's the point of the "HUM" terminal on the furnace if it's going to fry the humidifier? Or is it only meant for certain old school humidifiers that run on 120vac?
 
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Old 01-10-19, 11:53 AM
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Some control boards have a 120v HUM output, some have a 24vAC and some have both. That is an output switched on during heating. That was designed to work with manual humidifiers. You could attach a small 120v -> 24v transformer to the 120v HUM output. In your case... it's not needed.
 
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Old 01-10-19, 12:03 PM
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A 120v HUM terminal can be used to drive a dedicated 24vac transformer. Normally only powered up when furnace is running in heat mode with fan running. Can be helpful when you have a simple 2 wire humidistat.
 
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Old 01-11-19, 03:29 PM
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PjMax, thanks! Did you see my response to your question about the Nest?

Also thank you to Astuff.
 
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