Nest Gen 4 Thermostat keeps Humidifier running after furnace fan has stopped

[BobbyTwoDogs]

I have just upgraded my furnace to a Heat Pump.  I had the new Heat Pump installed professionally.  I noticed today that the humidity was low enough in the house that Nest turned on the humidifier.  However after the furnace turned off I noticed the humidifier water was still running.

The wiring is correct - please DO NOT suggest having a Nest Expert come to my house to look at the wiring.

The humidifier turns on if I go to the Nest Home app and turn up the humidity value.  It turns off when I go to the Nest Home app and turn down the humidity value.

There is a bug in the Nest Thermostat that needs to be resolved - there are thousands of people with this same issue online - so I'm not alone here.

When the furnace fan turns off the Nest Thermostat should turn of the Humidifier.  

In the Application there was a feature "Turn on humidifer only when heating" - this caused the humidifier to turn off when the fan stopped.  I don't see this feature on the Android Nest Home App.

Thanks,

Robert

[GabrielaG]

Hi BobbyTwoDogs,

Thanks for reaching out to the community. I'm sorry to hear that your Nest Learning Thermostat 4th gen keeps the humidifier running after the furnace fan has stopped, but no need to worry; I'm happy to assist you right now. 

To get a better understanding of the situation, please help me out by answering the following questions:

• When did the issue start?
• What other strange symptoms have you experienced since the problem started?
• Where did you install your thermostat? (in a room and on a wall or stand) 
• Do you see error codes on the thermostat screen?
• Have you tried any troubleshooting steps?
• Can you please send me a picture of the thermostat wiring?

Any additional details you can provide will be helpful.

Regards,

Gabriela

[BobbyTwoDogs]

Gabriella,

After doing research I discovered the * wire is no longer used for automatic humidifiers but the AQ wires will work.

I reset the wire from * to AQ+, reset the thermostat, chose the fan/heat options for the humidifier and now everything works.

Regards, 

Robert 

[GabrielaG]

Hi BobbyTwoDogs,

Thank you so much for your effort and keeping me updated. I'm glad to hear that your Nest Learning Thermostat 4th gen is working properly with the humidifiers.

Feel free to keep us posted if you have more questions.

Regards,

Gabriela

[NonnieA]

Hi, I think I am going to need to get my HVAC guy to fix this issue. Not all of them are super familiar with Nest- so if show him your post, I assume he will understand? Thanks for posting this!

[BobbyTwoDogs]

It was simpler than I thought. I have a humidifier that is attached to the air return of the furnace. It has a simple selinoid to turn the water on and off. The old nest thermostat used the * wire to regulate humidity. The nest Gen 4 uses either the AQ+ or AQ- to regulate the humidifier.  The only caveat is that you need to reset the nest thermostat and reconfigure it to recognize the AQ wire. The Google Home app won't let you reconfigure these wires without a reset and reconfigure.