Nest 3 and bypass humidifier wiring

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  #1  
Old 06-11-18, 03:29 PM
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Question Nest 3 and bypass humidifier wiring

Hi - I know this is an older thread but I have the same humidifier and have been reading through dozens of threads without a clear answer and figured i'd save a new thread. I was hoping you could just clarify a few things for me. I have also attached a few pictures to show my setup.

I am looking at setting up my Nest 3 to both my thermostat and stand-alone humidistat beside it. I have a Lennox ML193UH070P36B. Unlike the OP I do not have a humi terminal on the board and it appears the humidifier is connected to the W terminal (which I believe is heat?). I do have AC. Terminals are WCRGY. For reference the larger white cable bundle coming from the left of the picture is from the humidifier solenoid.




This is my thermostat

This is my humidistat

With that said, I dont believe I need a relay? I want to confirm if I need to change the wiring to the furnace to have a common wire (C). Which humidistat wire would I connect to the * and to the C (i know thats optional).

Thanks in advance for the help.
 
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  #2  
Old 06-11-18, 06:30 PM
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Welcome to the forums.

Always best to start a new thread. Keeps the confusion to a minimum.

You have at least six wires to your thermostat location.
When you switch to the nest you will be using a C connection for best operation.
Your nest wiring will be.....
Green - G
Orange - Y1
Red - Rh
Black - W1
Brown - C
Blue - *

At the furnace...... you will leave the humidifier solenoid white wire attached to the blue stat wire.
Remove the solenoid red wire from W and move it to C. That's it. You're done.
 
  #3  
Old 06-11-18, 09:21 PM
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That's great! Thanks for that. You saved me a boatload of time and money.

Since I will be rewiring some of the furnace terminals, should I switch the brown to the white and the blue to the C? I know they are non polarized but would it save issues in the future?
 
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Old 06-11-18, 09:47 PM
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Sure.... that works too..............
 
  #5  
Old 06-11-18, 11:38 PM
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Awesome. Really appreciate the quick and informative responses! Wish I could buy you a beer haha
 
  #6  
Old 06-12-18, 03:24 PM
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Alright so its installed but I am now getting an e74 no power from RH wire detected. Tried to switch to Rc with no luck. Did i trip a fuse?
 
  #7  
Old 06-12-18, 05:11 PM
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Cancel that! its working perfectly. Turns out my furnace has a pressure killswitch for the access door that kills power. For future reference for anyone else has E74 or E73 power issues.
 
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Old 06-12-18, 05:17 PM
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I usually tell the member to turn power off to the furnace/air handler.
By having the blower door open...all power was cut to your furnace.
 
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