Turning on Nest Fan?

I must be missing something simple and I feel like an idiot but after googling for hours, searching here and reading the wiki, I just cannot figure it out.

I have NST 5.0 up and working. I can go to the SmartThings App and see all the statuses and control stuff. I want to do something pretty simple. I want to turn on a switch and whenever that switch is on, it turns on the central fan connected to my Nest on and whenever it is off, it turns the central fan connected to my nest back to auto.

I am familiar with virtual switches. I’ve looked at the nest automations, but those seem to be the opposite, (ie. nest does something and that triggers another device). I’ve look at the SmartThings automations and that only seems to give me the options to set a thermostat temperature.

Arrrrrrgh. Someone please tell me the simple thing that I am missing.

For thermostats, the fan can be set on or auto. This is done with the thermostat capability

On means on, and auto returns the fan to hvac control

On Nest, when you set the fan on, Nest has a count down timer, so it will turn it back to auto on the countdown runout

You can write your own smartapp to use this capability, or use WebCore

I’m sure in the webcore forum, there are some examples of using a thermostat fan.

Nest manager has a built-in automation for fan circulation. I’m not sure it does exactly what you want in tracking another switch.

Thanks for the information, Eric.

I’m still a little shocked that there is no way to do this. It seems like it is supported in Stringify, so, i will probably just write a flow there.

This is all fairly new to me. So, I while I probably could figure out how to write a smart app using that capability, I’m not sure that I would have the time to figure it out and do it.

Can you point me to a good primer on writing smart apps?

I would think webcore is you easiest option

For smartapps, see smartthings documentation http://docs.smartthings.com/en/latest/

So forget that you have NST Manager installed for a minute.

If you were to define a Piston in WebCoRE (I will provide sample), you can turn the fan on. However, this is automatically going to use the timer built into Nest for what the Fan was last set to.

An example. Goto your Nest App and select fan and select 30 minutes. Let the fan start. Then select stop.

So now let’s say you create a Piston that triggers off Switch A turning on. You simply have the Nest Fan turn on as shown in the following Piston.

This will default to the timer last set when the Fan was initiated (you can go from 15 min to 12 hours). That’s built into Nest and no way you can get around this.

So if you were to set it to 12 hours, you should never run into any issues (from an automation standpoint). You can set whatever your default timer is directly in Nest based on how long you think a switch will be on for. Personally I wouldn’t exceed 1 hour on your Nest. Just remember that if someone manually turns the fan on for let’s say 15 minutes at anytime, that becomes the new default value for the countdown timer the next time the fan is turned on.

When your Switch is turned off (Else Statement) then you set Fan back to Auto (can’t turn it off), the fan will stop.

This should get you by your limitations.

As for NST Manager and it using the Nest API, these have been built using Nests functionality and fail safes so that things don’t break.

If you go with webCoRE, you run the risk that when SmartThings has an outage and your switch was on and it initiated the fan to turn on and then it has no way if communicating to turn it off again, your fan will run and run and run… Take that for what it’s worth because it could present other unknown issues down the road.

Here’s the simple Piston to do what you want that you can restore to your WebCoRE:

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