How to Use HVAC Thermostat FAN MODE as Trigger in Automations?

[NOTE: I will eventually migrate to CORE, but currently still using RuleMachine. I assume which rule system I’m using is irrelevant]

My thermostat (as all others, I assume) has two modes that the FAN can be in; one is ON, and the other is AUTO.

I want to build a rule that monitors for the state of that FAN switch (so that I can make other things either turn on or off, or open or close, etc).

trigger: HVAC Thermostat Fan Mode turns ON/OFF
action: Whatever I want (I got this part down already).

I’m not trying to monitor for the HEATING/COOLING state, or SETPOINT, or anything else.

Is there a way that anybody knows of to monitor for this particular state change?

It’s actually very relevant. Rule Machine, CoRE, or any other SmartApp references certain capabilities for devices, and in your use case they must be coded to look for “capability.thermostatFanMode”. If that is not in Rule Machine or CoRE, you won’t be able to trigger any action.

You’re in luck because CoRE does allow you to select that capability. You’ll see it as “Thermostat Fan Mode”. Now you just have to make sure that the device handler you’re using for your thermostat specifies that capability and sends the right event to trigger your actions.

I tested that with CoRE, and it does work; but I found a bug in my DH while testing that I’m in process of fixing.


Hi @sgnihttrams,

I think I may have found an issue with CoRE that I thought was a problem with my DH (and ST’s default DH). I’ve PM’d the developer asking him to check on what I’ve found and got it to work. Once I made that change, CoRE worked perfectly to turn on a light when I set my thermostat to circulate (my trigger and action).

If you decide to try CoRE, there’s just a simple change that needs done that you can easily do if the developer can’t get to it right away. Just let me know.


This is very cool. I guess perhaps I have a little more incentive to make the switch sooner now. :slight_smile:

Which DH do you use?

Some week ago I tried to trigger the HVAC status using CoRE. But it didn’t work. I can control the HVAC and the setpoint. That’s all working fine but I couldn’t trigger the HVAC mode (if cooling, heating or off). Have to say I didn’t try to set it up again since then.

Maybe I have to check my DH for an update?

I think you need help from the guys over in the CoRE threads…

Getting User Help with CoRE

Main Thread (and for reporting ‘bugs’)