HE360A to Trane XL80 - HUM terminal already occupied??

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Old 01-30-11, 12:09 AM
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HE360A to Trane XL80 - HUM terminal already occupied??

OK kids, just bought an HE360A and want to avoid using the sail switch. I have the proper terminals on the hot and neutral side of the board of my furnace (Trane XL80) but the hot HUM terminal is already occupied.


The Neutral side of the board has the HUM terminal empty...


The black wire from the hot HUM terminal goes to a box on the left side of the furnace...


I also have a one outlet box with switch on the right side of the furnace below where I plan to mount the humidifier. Power is being supplied to this outlet from the main breaker box in the home.


My questions for the experts...
Why is there a wire occupying the HUM terminal already and can I use this terminal to wire my new humidifier?

Can I use the existing outlet and do I need a transformer to plug into the outlet?

How accurate will the humidistat be if I mounted it on the return duct if everything is in a tiny closet or would I be better off installing that on the wall outside of the closet?

Can someone please explain how I am to wire this all up with this existing setup? I can provide a wiring diagram for the furnace if needed.

Thanks in advance for any help you can provide!
 
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Old 01-30-11, 05:07 PM
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Did you open the junction box to see if the wire was used? If it is use, what is it tied to??

The humidistat is going to read the air inside the return, not the area around it if yo mount it on the return. You could place it outside of the closet if that is your main hall way next to the stat?
 
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Old 01-30-11, 08:24 PM
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I didn't open the box up, but I believe it is where the furnace is getting it's power from. Here are the schematics if that helps.

This one shows the connections on the control board. You can see that wire BK/3 is connected to the HUM terminal.


This image is the schematic of the box. If I'm reading that right BK/3 is connected in series to "115 volt power supply."


I hope this helps solve the mystery. I'd rather not go digging around opening up that box if I can avoid it. Thanks!
 
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Old 01-30-11, 08:31 PM
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on a trane, the wire is sent to the power junction box to wire an outlet from there. you don't have to use that wire and can just add a new wire and new outlet if you wish. Just tape off the removed wire on the HUM terminal
 
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Old 01-30-11, 09:17 PM
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OK, great! So does that mean I can't I use the existing outlet on the side of my furnace? Or can I wire the humidifier directly to the furnance HUM connections? I could use a little guidance on what connections need to be made. Thanks!
 
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Old 01-30-11, 09:22 PM
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you'll have to decide which way you want to install the unit. New outlet or you'll need a sensing relay
 
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Old 01-30-11, 09:43 PM
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OK, where does the sensing relay fit in to all of this? Does this ensure that the humidifier only runs while there is a call for heat? I thought that was the whole purpose of connecting the humidifier to the HUM terminal. Can you spell out the connections that need to be made with this relay/humidistat/humidifier? Thanks so much for your help so far.
 
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Old 01-30-11, 10:09 PM
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yes, relay would take place of the sail switch and only active with a call for heat when attached to inducer neutral wire. The relay is only needed if you don't use a new 120v power outlet.

HE360A USED WITH SWITCHED OUTLET


HE360A USED WITH SENSING RELAY

 
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Old 01-30-11, 10:34 PM
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hvactechfw, you are a HUGE help. Thanks so much. One last question, I hope. I think I will go with just installing a new outlet next to the current one already mounted on the furnace. If I do that I don't need to actually hook up that outlet to the house electrical, correct? Just wire the HUM and neutral to the outlet and plug in the humidifier? Sorry for such simple questions. I really appreciate the help so far.
 
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Old 01-30-11, 10:37 PM
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yes, you are correct. hum to Hot side of outlet and neutral to neutral. outlet will be grounded through screws into cabinet of furnace of metal 2X4 box for outlet
 
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Old 01-30-11, 10:50 PM
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Perfect. Seems to be the easier way to go. Thanks again for everything.
 
 

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