SmartThings Community

Using to Nest humidity reading to trigger humidifier?


(kevin mckenzie) #1

I received a Nest over the holiday and noticed it had the ability to read humidity and turn on a whole home humidifier. My hvac system in my house does not allow me to install a whole home system, so I have made a stand alone unit using ultrasonic misters. (here is a link to a video with a system similar to what I have assembled: )

I think there are two ways of triggering this:

  1. I have installed nest-manager, however I cant tell how to build an automation off the humidification readings.

2 I noticed that the nest sends 24vac down the connector label “*” when the system is calling for the humidifier to turn on. If there was a zigbee or zwave device that could trigger on 24vac, and turn on smart outlet that would work.

Any suggestions? Thanks in advance for any help or suggestions!

(Eric) #2

You can use CoRE to create an automation that reads the Nest Humidity, and sends on/off to a switch/outlet to turn on/off your humidifier(s)

(Emerson Vier) #3

@bookup do you need Outlet Z-wave or Zigbee

On Android APP -> Marketplace ->SmartApps ->Climate Control ->Smart Humidifer than setup

I hope is help you.

(Robin) #4

There are several binary sensors on the market that can take an external (dry contact i.e. 0v switch) input but nothing that can translate 24v. (As far as I’m aware)

Here are some UK examples:

The closest thing would be the MIMOlite but that has a max input of 16v

However if you take the 24v output from your Nest Thermostat and use it to toggle a dirt cheap 24v (dumb) relay, you could use the relay output to drive any dry contact sensor.

Personally I like the Fibaro Contact sensor (gen5) but you have a lot of choice… Just search or ask this forum about sensor compatability before purchasing!

Of course, the dumb relay (triggered by the Nest output) could also switch power to the humidifier directly! This setup would be very easy and very cheap, for example a dumb relay costs just £3 in the UK.

(Robin) #5

Cheap relays:

A better option for a safe and ‘proper’ install would be to use something like this. It can be installed in a compatable fuse box keeping things neat:

(Emerson Vier) #6

I use Smart Humidifier

But they only turn on when the humidity was 35, my set up is 45

(kevin mckenzie) #7

I attempted to implement this with core but found the results to be inconsistent. I was unable to determine root cause. I have since installed smart humidifier and will post if this is sucessful with the nest. I suspect there might be an issue with “nest manager” since its humidity readings differ from the native nest app.

Thanks for everyone’s help

(Eric) #8

as an fyi, humidifier control is now a builtin automation in nest manager. It works with humidifiers controlled by your nest, or standalone units attached to a smart switch.

(Kevin) #9

Hi! Where do I access that humidifier control in NST Manager? Can’t seem to find on Mobile App, or IDE?

(Eric) #10

(Kevin) #11

thank you so much for that- I see there are supposed to be a number of pre-available automations, but when I go into Automations in the Mobile App, I go into NST Manager and I don’t see any. So, for example, all those automations in the link you provided do not show. I am wondering if somehow my SmartApp NST Automations is not configured right? Or NST Manager is somehow not set up to receive the automation code? I have everything published, followed instructions I think fairly well. I have nest dev account and activated all the device settings and such. Still not sure what could be missing?

(Eric) #12

make sure you are using the classic smartthings app.

Then make sure in the page shared above that the instructions were followed to install NST manager, the automations, and the device handlers.

The automations work with thermostats mostly, so you should be able to see automations from the NST manager app (in smartthings classic)

(Kevin) #13

Appreciated. I think I may reinstall. Make sure my token and client ID / secret is working perfectly. I wonder, now that I am thinking about, should I add the client ID and such to NST automations in my SmartApps as I did the Manager?

Thank you,

Kevin Reid

(Eric) #14

The built in automations are children of the parent, so you don’t enter the tokens for them

(Kevin) #15

Roger that! Going to tackle tonight. I’ll let you know how it goes!

Thank you,

Kevin Reid

(Kevin) #16

so I found the automations. Had to reinstall NST Manager. Probably didn’t do correctly first time. Have learned a lot in last two days. Now, trying to get through the Humidifier to come on if outside temp = “x” and inside humidity (from nest thermo) = “Y”. Issue right now is, the way the automation is designed, it relied on a controllable switch (thing), not the thermo to turn the Humidifier on / off. I need to use the Nest. Thoughts?

(Eric) #17

Read it closely, it has links to a driver that let’s you use the thermostat humidity on/off if you have one wired to your nest.

(Kevin) #18

Thanks so much Eric, really appreciate all this time. So, I have been trying to work my way through this for the last couple of days. I got everything installed now as stated - NST Manager and all automations - I see them. As I work through the Humidifier Automation, it states it needs a switch (as descried in the link you sent me as well), but it seems I can’t use the Thermostat as a switch. It wants an external Smartthings enabled switch. It’s really too bad the Nets itself can’t be the switch, since that’s all a thermo is: a sensor and switch. Do you know anything about that? Possible to actually use the Nest as THE switch? And if not, I see the link as I move through the documentation that gets me to a GitHub source code ( This supposedly, possibly along with another sister code, allows you to control the API to the Nest Thermo as a switch? I just seem to be missing something here? I try to install the source code, from code as a Smartapp, but maybe that’s not what I am supposed to do with it? So I really have two questions, after all that - 1) Is there any sure fire, direct way to use the Nest Thermo as a Switch in the Automations app, and if not, 2) how do leverage / install that code from that link if that’s even what I’m supposed to be doing?

(Eric) #19

The github you reference above is a device handler, so it is installed in the IDE under “My Device Handlers”

then in the smartthings classic app, you need to add a new device, selecting that device handler you installed, then configure that new created device.

Then you should find it in the NST Manager automations when looking to select the control for the humidifier.

You should make sure the device handler works before configuring the automation to use it.

(Kevin) #20

Ah! Interesting. I will do tonight. So, last question would be if I do this setup successfully - does that technically make my nest thermostat as a switch so I can use the Thermo in the NST automation as designed? I just would hate to have to add an external switch to this system. For many reasons.

Thank you,

Kevin Reid