Bypass Humidifier to Nest


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Old 09-10-17, 02:16 PM
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Bypass Humidifier to Nest

I have a bypass humidifier with 2 wires coming from the furnace, through a transformer, connected to the water solenoid, and then wired to the humidistat. I'm wonder how to wire to a nest thermostat and whether I need a relay to use the new thermostat. I'd like the humidifier to only come on with heat. I've done up a simple wiring diagram of what is install right now:
 
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Old 09-10-17, 02:27 PM
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Welcome to the forums.

A fairly easy installation job. You will need one extra wire in the cable from the thermostat to the furnace. One of the solenoid wires goes directly to C where the furnace low voltage connections where the thermostat wiring connects. The other wire goes to the * on the nest. Configure the nest for humidity with heat.
 
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Old 09-10-17, 02:48 PM
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Thanks for the reply. I'm a little confused on the wiring still. Where does the transformer come into the wiring? Right now there is no C (common) wire from the thermostat to the furnace, just red, green and white.
 
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Old 09-10-17, 04:16 PM
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The wiring is just as I've shown. You don't need the transformer. BUT you need an extra wire from the furnace to the stat. One wire goes from the solenoid DIRECTLY to C on the furnace.... not the nest. The other solenoid wire goes DIRECTLY to the * terminal.

Red, green and white. What is this.... just a furnace... no A/C ?
 
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Old 01-07-19, 07:16 AM
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I hate to piggy back on this thread but I have a similar setup. My humidifier is a wait 6000 and i've removed (destroyed) it while trying to wire it up directly to my furnace. So my last attempt was to wire the Nest directly to the 2 wires of the solenoid. Which seemed fairly straightforward from what i read in the nest pro setup. I have a carrier furnace with a 24Vac HUM terminal on it, but i chose to just use the COM terminal to keep w the nest pro instructions. I wired the nest's * to one end of the solenoid and the furnace boards C to the other. When i did that and ran the test i could see that the solenoid was being opened and it was running water down to the evaporator pad. I thought i was victorious...

Shortly after that my nest was climbing in temperature to values that were not correct and then my furnace fuse blew. and it looks as if my solenoid is melted.

I have an HRV system setup as well, not sure it that might have been an issue? And i also have a common going to the nest as the first season with it it kept losing charge.

My question is, do i need a relay?

This is the solenoid that comes w the wait 6000:
https://www.airkinghq.ca/enlarge/2185160/11355410

Thanks in advance
 
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Old 01-07-19, 10:39 AM
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Welcome to the forums.

That Wait unit is a complete standalone humidifier. It's not designed for external connections.
If you connect to the solenoid..... you must disconnect the solenoid wires from the internal wires of the unit.
 
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Old 01-07-19, 10:51 AM
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Yes, i did disconnect them from the unit. I've disconnected everything, even removed the electric humistat that was originally there. I'm trying to let the nest act as the humistat and open the solenoid when it decides humidity is needed.

At the moment, I'm only using the 2 wires from the solenoid: one to the nest's * and the other to the common on the furnace control board.

I'm at the point now where i've fried the entire unit, i was hoping that i would be able to salvage something just handling humidity by having the nest control the solenoid. I'm assuming that this solenoid isn't designed to do what i was trying to do?

Thanks again for the response. I've been pouring over these forums all weekend. Great stuff in here.
 
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Old 01-07-19, 11:01 AM
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Connecting that solenoid you linked to should not have caused any problems.
It's labeled as 24vAC which is correct.
 
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Old 01-07-19, 12:12 PM
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Maybe it was fried when i originally fried the humidifier. The solenoid is all bubbled out. I'm not sure if that was from when i wired it last night or if it was from before when i was trying to hook up the furnace control board to the wait 6000. I think i'll quit while i' ahead and get someone in to look at it. I'm out of my element and i've already destroyed a humidifier.

Thanks again for the help.
 
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Old 01-07-19, 12:18 PM
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Nah..... replacement solenoids are available and aren't that expensive.
 
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Old 01-07-19, 02:26 PM
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Thanks Pete, I'm gonna pick this back up when it gets a little warmer and i don't have to stress out about my wife screaming at me for messing with it.
 
 

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