# Aprilaire 700 humidifier wiring installation



## seanbie (Dec 13, 2010)

I have everything ready to go for my humidifier but the wiring. The unit plugs into an outlet for power. There are 2 brown wires that come down from the humidifier. The Control unit is on the intake and has no wires connected. First I need to know what type of wire to use and second where everything goes. The transformer "load" side it has a place to connect a "10VA" and "24Vac". A black and white wire are coming out the back. One of the brown wires goes to the transformer but where and what do I do with the wires out the back? The transformer has 120v input/ 24v output. what does the broken line between the C from furnace to thermostat? Do I have to run a wire the whole way to my thermostat for "G" (fan) Inputs?


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## richiemoe (Mar 17, 2010)

First you need to know if that hum tab is 120 volts or 24 volts. I cant see the diagram very good on my computer. The 2 brown wires coming out of the humidifier are the solenoid coil to open and let water into the unit. One of the brown wires need to go to a 24 volt common and the other brown wire will need 24volts that is ran through a humidstat. You can use thermostat wire as long as all your voltage is 24 volts. If the hum tab is 120 volts you will need another transformer or you can have a current sensing relay. That keeps the humidfier from running when the blower is not on.


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## richiemoe (Mar 17, 2010)

The broken c wire is only showing that you might or might not have that wire installed in your instance. If you have a/c installed on this furnace you should have a g wire at your t-stat.


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## richiemoe (Mar 17, 2010)

Looks like a pretty straight forward wiring diagram. You will need to hook that transformer to the 120 volt power coming into the furnace. Then use 18 gauge stat wire uo to your controller. Having it wired like that is to ensure that the humidfier only runs when it is in heating mode or the fan is running. Looking at your picture of your board you have a "g" wire at the furnace. So you would take that green wire off your board and hook it to the controler, then take a wire from the Gf out on the controller back to the furnace board.


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## richiemoe (Mar 17, 2010)

On your diagram that says furnace. That is the terminals on your circuit board of your furnace labeled r,c,w,y,and g that you show in the top picture. The black and white wires of your transformer are the 120 volt side of the transformer. Black goes to hot and white goes to neutral. I am talking about the transformer in the lower right hand of the wiring diagram for the humidifier. Your furnace is powered with 120 volts so you can power that transformer with the power that comes to the furnace.


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## seanbie (Dec 13, 2010)

I got everything hooked up and it is all working the way it should. the wiring had no problems. had to tighten the valve where i tapped into the water because to much was coming through and over flowing out the bottom of the humidifier. Thank you for the help and breaking it all down so it made sense to me.


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## beenthere (Oct 11, 2008)

seanbie said:


> I got everything hooked up and it is all working the way it should. the wiring had no problems. had to tighten the valve where i tapped into the water because to much was coming through and over flowing out the bottom of the humidifier. Thank you for the help and breaking it all down so it made sense to me.


Its suppose to have water coming out the bottom.


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## Maack (Dec 27, 2010)

I'm doing the same installation with an Aprilaire 700 automatic , except that my furnace control strip is a little bit different.
This furnace is a brand new (December 2010) Carrier 58 cva gas fired hot air unit.
My terminal strip doesnt have the *C* terminal,
it has a *Com24* terminal.
Vertically , from the top the terminals are:

W2
Y1
DHUM
G
Com 24
W/W1
Y/Y2
R

The top 3 terminals, the W2, Y1, and DHUM terminals are empty.
The 5 existing thermostat wires connected to the terminal strip are:
Green to G
Blue to Com24
White to W
Yellow to Y/Y2
Red to R

Also, instead of using an independant 24 V transformer like Seanbie is using, my furnace has a separate 24 V quick-connect hum tab that Carrier says is to connect up the humidifier to and then run it from there to the controller and then back to the Com 24 terminal.

Can I/ should I , use the 24 volt quick-connect tab rather than the separate transformer ?

Aprilaire's instructions on power going up to the humidistat are to use the 24 volt R terminal and the C terminal , however my terminal strip doesn't have a *C* terminal. It shows the *Com24* terminal.
I'm also asking if this *Com24* terminal is the same as Seanbie's *C* terminal?
thanks:
Maack


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## beenthere (Oct 11, 2008)

Yep, the comm24 is the same as the C terminal.

You can use the furnaces tabs for the humidifier.


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## Maack (Dec 27, 2010)

Thank you:

Its good to just double check once in a while and get confirmation on questions!


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## emptyjacket (Dec 17, 2011)

Just wondering if either of you could help...
We have a blue wire running from the thermostat to the furnace, but it's not connected to anything. Does this wire play a role in the wiring of the humidifier at all?
Thanks in advance!


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