Using ecobee3 humidity sensor to trigger my humidifier?

Anyone know if this is possible? I have smarthings and i have the ecobee3. i know the main unit (not the remote sensor) has a humidity sensor in it. Is there a way to access this in order to trigger the smart outlet that my humidifier is connected to?


See if this app does it (long read)

If not you could just connect a humidity sensor with the switch, independently of the Ecobee.

The Ecobee 3 has a built an auxiliary relay which can be used for a humidifier. Are you trying to switch on and off a humidifier that’s built onto the furnace or something separate? Either way I can think of a couple ways you can do this…

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Please share your thoughts as I too am interested.

Well, the auxiliary output on the EcoBee 3 can be used for a ventilator, a humidifier, or a dehumidifier. However it’s only rated for like 24 votes and relatively low amperage . It will work fine for a humidifier that is built on to your furnace, clicking the water relay on and off. You need to tap 24 V off of your furnace run it through the relay and then to the humidifier than the other side of that relay goes to ground. It works great and it’s how mine is currently set up. In fact I was having trouble and I called them and their tech support walked me through doing it and explaining that is just a dry contact.

With that said if you had a external humidifier that you want to click on and off based on the EcoBee telling it when to do it you can use a RIB relay rated for 24 V on the pilot side and 120 on the voltage side (RIBU1C ?) to turn on and off a full size machine.

@storageanarchy - can you see the value of the aux output through your DTH? I.e. If someone set it up as a humidifier can you see it turn on and off and maybe they can just use that to turn a standard zwave/zigbee outlet on and off?

Thanks for the replies. I don’t have a device connected to my furnace and while it sounds like a great idea @vseven it might be a little too complicated for me to setup. I was think more along the lines of using the standard zwave/zigbee outlet and using SmartThings to read the humidity sensor in the ecobee3 to trigger the outlet. Is that possible?

Otherwise, I could always just get a humidity sensor and do it that way. Was hoping to avoid having to get another device since the ecobee has one built in…

While the configuration of the Aux is visible, and whether it is on or Aft is derivable from the API, it cannot be controlled independently, other than indirectly by setting absurdly high humidity target.


I don’t think it needs to be commanded. I think as long as it is visible the @op can use its status to control a standard Z wave outlet. The nice thing about the EcoBee is for humidity it can be set for frost control, it will automatically raise and lower the humidity based on the outside air temperature to prevent frost from building up on the windows. If he can see that the EcoBee is trying to turn the humidifier on he can then turn on his actual humidifier and vice versa using a simple SHM custom rule.

@drew571 - You wont need to wire up anything… Just telling the EcoBee that it has a humidifier should be enough for it to try to command the output on and off and, if I’m understanding Barrys reply, that point should be readable.

I do this in webCoRE using a plug in 120V dehumidifier.

Yup - just monitor equipmentStatus and when that string contains the string ‘,humidifier’ then turn on the humidifier (or when equipmentOperatinState contains ’ hum’). Note, however, that the Ecobee 3 & 4 will only humidify when the heat is on, and the heat will turn off when the temp is reached (which is likely to be before the humidity is reached).

Better approach is that shown by @Michael_D - just use the humidity sensor in the thermostat. If you want to take advantage of the humidity setpoint that the Ecobee calculates (based on you window efficiency and the outside temperature), you can used the current value of thermostat.humiditySetpoint as the target instead of hard-coding it.

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You can select the humidity sensor in the Ecobee thermostat as you can for any other device, so you won’t need a separate device.

excellent. so i think i still need a little help. i’m assuming i have to “add a thing” in the smartThings app. how do i select just the humidity sensor as a thing?

No, you don’t need a new Thing other than the Ecobee Thermostat. Just select the thermostat as your humidity device within whatever app you use to turn on your humidifier.

There is a Smart Humidifier SmartApp in the SmartApp Marketplace (in the Climate Control section) that should do what you want to do.

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That worked great. Thanks Barry! Exactly what i was looking for…


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I want to do the same thing with my ecobee4. However, I want to use one of the ecobee sensors I have in my basement to gauge it off of. The only thing that shows up in that smartapp is the ecobee thermostat itself. Anyway around this?


The sensors are temperature only AFAIK, they wouldn’t have humidity so they shouldn’t show up in something looking for humidity.

Nope, like Allan said the Ecobee remote sensors are Temperature and Motion/Presence only.

You’ll need a humidity sensor of some sort (I use Aeon or ZooZ multi-sensors).

Yea… I just pulled up my Ecobee app after I posted and realized the sensors don’t have humidity… Damnit…

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@drew571 Can you please post what EXACTLY what you ended up doing to control your dehumidifier? I am confused. I am not sure if you purchased additional smart apps from the guy selling them earlier in this thread or if you used the smart app that is in the ST classic app (if so, what is the name of the app?). The app I saw in ST marketplace did not seem to offer the option to switch a plug on or off after sensing humidity, but I do not have a sensor yet, so maybe that is why it does not show a way to control a smartplug in the smart app??? Additionally, did you end up using the ecobee3 built in humidity sensor or an external one or both? Also, how were you able to link it to control your dehumidifier? Did you do it with a smart plug or what? Please summarize the solution you used BUT IN DETAIL with any links to code etc., so that I and others can actually benefit from your knowledge the same way you did (from other peoples knowledge) with this solution.


I actually just used the Smartthings app, probably on my iPad to set it up. It’s all there, i just didn’t realize it. I just told the app to turn on a leviton smart plug that i have whenever the humidity in the room fell below the level that i specified in the smartthings app, and then turn it off when it went above the desired humidity. The humidity sensor I used was the one in my ecobee 3 thermostat. It was available in the smartthings app as well as long as you’ve connected the two devices.