Aprilaire 700 Wiring Questions

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Old 01-04-11, 09:43 PM
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Aprilaire 700 Wiring Questions

Okay, so I'm new to HVAC wiring and really don't know where to go from here. I have an Aprilaire 700 humidifier and an American Standard model TWG025A140B1. I can handle the installation up to the point of the wiring. I've been trying to figure out what I have in the furnace from this wiring diagram:


From that, I see that I already have a 240V to 24V transformer (technically 230V to 21V; I don't know if that matters), which is on the left in this picture:


What I'm thinking is that I could use the low voltage red and blue lines coming out of that transformer for the R and C humidistat terminals. Is this correct?

The other mystery is what to wire the W/G and Cf terminals to. The diagram shows a "low voltage field connection" with lots of low-voltage wires available, and two of them (white) seem to be unused, terminating into a wire nut in this picture:


Perhaps these would be useful in some way, maybe for the W/G and Cf terminals?

Please help; I'm really at a loss and (obviously) in over my head here, but would love to be able to do this myself.
 
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Old 01-05-11, 05:44 AM
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I will have to get back to you on this tonight when I have a chance. Please bear with me.
 
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Old 01-05-11, 05:56 AM
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No problem. I'm grateful for any help you can give me.
 
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Old 01-05-11, 07:14 PM
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What model # of humidisat did you get? There are a few that are getting a newer model.
 
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Old 01-05-11, 07:57 PM
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It's model #60.

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Old 01-05-11, 08:10 PM
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Ok, are you sure it's 60, not 58? You sad Cf in your earlier post, and 58 has that, 60 don't.
 
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Old 01-05-11, 08:33 PM
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You're right, of course. It's the 60, and the wiring instructions that came with the humidifier must be for the 58. The wiring instructions in the little booklet with the humidistat are completely different, and this is the first time I'm seeing them. So, I'm even more lost than I was before.

So, now the R and C humdistat terminals get wired to R and C "on the furnace terminal strip." Problem is, I don't see where my furnace terminal strip might be. What you see in the pics above is all I got. Along with this monstrosity:


If I could find this terminal strip, I'd be golden. But I don't see one, and I don't know what the R, C, G, Y, and W terminals might correspond to.

And I don't know where to wire up the transformer to connect it to the two H terminals on the humidistat, or if I even need the transformer, given that I seem to already have one (in the pics from my first post).

Whew, this is confusing.
 
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Old 01-05-11, 08:46 PM
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Ok, The wires will be the wires are wire nut up together since air handler don't ahve a board like a furnace.

so, this where you join the wire nut.

Humidistat--------wire from air handler itself.
R-------------------red
C-------------------blue
W------------------green

Are you going to hook up the hard wired transformer for the humidifer/H side?
 
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Old 01-05-11, 09:21 PM
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Originally Posted by Jay11J View Post
Ok, The wires will be the wires are wire nut up together since air handler don't ahve a board like a furnace.

R-------------------red
C-------------------blue
W------------------green
I'm assuming you mean the three groups of wires highlighted in this picture:


Originally Posted by Jay11J View Post
Humidistat--------wire from air handler itself.
Not sure which wire you mean here.

Originally Posted by Jay11J View Post
Are you going to hook up the hard wired transformer for the humidifer/H side?
Well, that's the thing. I'm not sure if I need to hook up the transformer that came with the humidifier (120V to 24V), since I already have the 240V to 24V transformer in the air handler. Should I find a nearby 120V source and use the transformer that came with it, or can I somehow branch off from the 24V wires from the transformer already in the air handler?

And where would the Gf terminal get wired to? It's supposed to go to the G terminal on a furnace terminal strip, but since I don't have a strip....
 
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Old 01-06-11, 09:43 PM
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Just a thought... due to the limited space available on the supply, my plan is to put this thing on the return. Would I be better off with a bypass like the Aprilaire 600 in this situation? I'd rather know the hard truth now while I could still do something about it than after I cut the hole for the 700.

You can see what I'm dealing with in this pic:
 
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Old 01-07-11, 05:21 AM
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Looks it may be tight between the air handler, and the main trunk. IF the 700 don't fit there, then you'll have to go to the bypass unit.
 
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Old 01-07-11, 05:23 AM
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you could use a 600, or the 700 on the return. The 700 on the return would most likely need a trap to keep the water from being pulled back in to the humidifier and that in turn usually causes leaks.

Well, that's the thing. I'm not sure if I need to hook up the transformer that came with the humidifier (120V to 24V), since I already have the 240V to 24V transformer in the air handler. Should I find a nearby 120V source and use the transformer that came with it, or can I somehow branch off from the 24V wires from the transformer already in the air handler?
you can use the transformer in the AH, however, I don't recommend it. A better solution would be to find a nearby 120v power source to power the X-fmr.
And where would the Gf terminal get wired to? It's supposed to go to the G terminal on a furnace terminal strip, but since I don't have a strip....
GF will connect with the green wire that will be wired with W
 
 

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