Aprilaire 700 and Lennox EL296UHV

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Old 03-07-15, 01:02 PM
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Aprilaire 700 and Lennox EL296UHV

Hello all, I am having some issues getting my Aprilaire 700 wired up. Plumbing and everything else is good, but electrical is where I need some help. Normally electrical is my strong suit, but has be a bit confused.

First, in recommended installation method allows the humidifier to turn on without a call for heat correct? It looks like Thermostat G goes so the humidistat G and then the humidistat G output goes to the furnace G. That is what accomplishes that correct? I assume it is since it looks like it calls for me to disconnect the G between the thermostat and the furnace. What if I want the humidifier to only come on when there is a call for heat?

Second, I assume I want to connect to W1 and not W2 correct? I assume that W1 stays active even when W2 is turned on for the second stage.

Lastly I am having trouble figuring out how to hook up the 110v/24v transformer. There isn't a nice box on the outside of the furnace. The armored cable just goes directly into the furnace so there isn't anyway to get to the 110 that I can find and still protect the terminals. Any thoughts on this? I've attached a picture below to show the problem. The location where the power comes in is circled in red.
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Old 03-07-15, 01:17 PM
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In case anyone wants the link to the furnace install manual, here it is.
http://tech.lennoxintl.com/C03e7o14l...bC/507264d.pdf
 
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Old 03-07-15, 07:21 PM
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Looks like a short cut install. There should be an electrical box on the side of the furnace where the power comes in and then goes to the furnace. This box would contain the service switch usually on a red plate. Should be easy enough to add.


Page 42 of the manual talks about the Icomfort system. Is that what you have ? It would appear that that thermostat can control the humidity and has a HUM control relay on board.

Don't connect anything without checking with me. I'll help you get it right.

Also.... if you end up using the #62 automatic thermostat..... I wire them so that the humidifier only runs when the furnace is heating. It is not cost effective to humidify cool air.
 
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Old 03-07-15, 08:02 PM
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Yeah, a shortcut doesn't surprise me.... Any recommendation on how to remedy it? I took a picture from the outside of where the cable goes in. I don't have an Icomfort so I'll be using a humidistat. I have the model 60 unit.
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Old 03-07-15, 08:38 PM
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So is it really a shortcut? I was thinking that since there is clearly a Junction box inside the furnace it seems that maybe it isn't?
 
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Old 03-07-15, 08:51 PM
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Do you have a safety service switch at the furnace ? By code you should have.

I would turn power off. Remove the wiring from the furnace and install a 4" box. Use a trim ring or look for a 4" red plate. You can mount your transformer to that box. A chase nipple will help hold the box to the furnace and transfer the wiring into the furnace safely.

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As far as the humidifier...... you'll follow this diagram.

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Old 03-08-15, 08:00 AM
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There is no switch by the furnace. It is in the same area as the electrical panel and is on its own breaker so maybe it wasn't required by code? The house is new so I know things were all inspected, but I don't know if a the inspector missed it or not.

Also, could I put an outlet in with the switch? Would be more convenient than moving an existing box that is used by the hot water heater exhaust fan for the fan on the 700.

In the wiring schematic you showed, I should use W1 for W correct? Also, is that schematic such that it only calls for humidity when there is also a call for heat?
 
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Old 03-08-15, 08:29 AM
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If you have an existing box with receptacle for the WH..... you could put the transformer on that box.

Yes.... you would use W1 and the humidifier will only run whit a heat call.
 
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Old 03-08-15, 08:46 AM
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That box is in the ceiling and probably 10' from the furnace. I was going to move it to plug the humidifier in to the same outlet. It would be easier to just install a single outlet and toggle switch attached to the furnace if that is allowed.
 
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Old 03-08-15, 09:58 AM
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On the side of the furnace it is.
 
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Old 03-09-15, 08:10 AM
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Just talked to my local electric inspector and since the breaker box is within eyesight of the furnace, a switch is not required. Thus the reason they didn't install one. I will likely have to install my own.
 
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Old 03-09-15, 08:20 PM
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Just install a box with a receptacle. Leave the switch out if not required.

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Old 03-11-15, 11:15 AM
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Well if I end up installing a wall around the furnace, to facilitate a workshop, I may need the switch. :-)

If you notice in my original picture, there is already one hole in the casing that feeds into that box that is circled. Do I just remove that box and drill and extra hole for the transformer and move the wires out to the external box?
 
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Old 03-11-15, 11:20 AM
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You would open the box you circled and disconnect the wires. Now pull that cable completely out of the furnace. Install the new junction box. Pick a knockout in the back of the new box that lines up well with the knockout in the furnace. Use a chase nipple to connect the two boxes together.

Reinstall the supply wire into the new box. You'll make splices in the new box and bring two short pieces of wire back into the furnace thru the nipple. Pick a knockout in the box for the transformer.

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Old 03-11-15, 11:52 AM
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The one knockout is needed for the transformer though right? I'll need a second knockout for the normal power wires.
 
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Old 03-11-15, 06:01 PM
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Yes... you'll need another knockout for the transformer.
 
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Old 03-11-15, 06:24 PM
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That'll mean drilling a hole :-)
 
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Old 03-11-15, 06:31 PM
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If you used a 4" square box live I've shown..... you have 9 knockout holes around the box. Putting the feed into one leaves 8. Just pick one of the 8 that is in a good position.

Probably bottom left.

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(best picture I could find)
 
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Old 03-11-15, 06:59 PM
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Ah. So that one has the transformer on the outside of the box rather than internal to the furnace. I was thinking it needed to be internal. That way it would all be protected.
 
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Old 03-11-15, 07:04 PM
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Very rarely is a second transformer mounted inside the furnace..... usually no room or place to put it.
 
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Old 03-11-15, 08:06 PM
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So it just dawned on me, can I use the HUM or ACC connections on the furnace control unit instead of the transformer?
Thanks.
 
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Old 03-12-15, 01:09 AM
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The HUM function is performed in the automatic humidistat. You could pull power from the furnace but I don't recommend it.
 
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Old 03-28-15, 07:12 AM
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Is there anything to prevent me from drilling a small hole between the top and bottom compartments? It would make wiring a lot easier as the humidistat wires could come in from the side of the furnace where the air filter is.
 
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Old 03-28-15, 09:55 AM
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You can drill a hole. Watch where the metal chips go. Metals chips and control boards don't mix.

I carry snap in grommets for just that purpose. You need to make sure the sharp edge won't cut the wire.

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This is a larger one. They come in all sizes.
 
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Old 03-28-15, 12:40 PM
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Any idea where to score the small ones? Looks like the smallest on HD carries is 1/2". Don't need one that big for such a small wire.
 
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Old 10-25-15, 12:54 PM
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So this may seem like a dumb question, but does the little bracket on the outdoor temp sensor mount to the outside or of the house or in the basement?
 
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Old 10-25-15, 01:08 PM
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Good to see you back.

The outdoor temperature sensor needs to be mounted outside of the house.

I usually sneak the wire out with the A/C lines and mount the sensor near the A/C disconnect.
Otherwise... just about anywhere outside will work.

The sensor monitors the outside air temperature and as it gets colder it reduces the amount of humidification added to the air.
 
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Old 10-25-15, 02:22 PM
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Yeah I wanted to snake it out there but that is the southeast side of the house so I need to go to a different area. I'll drill a nice tiny hoke.
 
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Old 10-28-15, 05:11 AM
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BTW, should I seal up that grommet after I run the wire? I noticed that that the current penetration as all sealed up (it appears at the factory). It's all low temp area so I would think regular silicon caulk would do it.
 
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Old 10-28-15, 09:10 PM
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Typically if it's not in the direct sun it can go anywhere. Even directly under the A/C disconnect.

Wherever you bring it out... you want to make sure the hole is sealed. Silicone is fine.
 
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Old 10-29-15, 06:55 PM
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Sorry, I meant the wire from the top half of the furnace to the bottom half. I did seal the hole to the outside of the house.

And thanks for all your help. With the exception of tacking the wires, everything is installed and working!
 
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