Thanks for all of this info, I even contacted Nest and got a reply saying that there thermostat would not do what I wanted. Im still looking
With the clever use of a relay or two and maybe an aqua stat it should work, Nest meant most likely directly out of the box it won’t do what you want.
I’m not overly impressed with who I spoke to at Nest or her supervisor about troubleshooting why I had an intermittent use of my humidifier. No matter how many times I explained normally my Orange wire which is connected to a relay to close the for the humidifier to kick on is hooked to the * on the Nest and it won’t do nothing now and hasn’t for a week, but if I disconnect the White wire going to the W connection and hook my humidifier wire to the W connection and turn the thermostat up, then the humidifier would kick on.
Took 15 minutes to get em to send me a new back plate.