How does Nest Learning Thermostat control a humidfier? (NOT a wiring question)

[dan_kle]

I just installed a Nest 3rd gen Learning Thermostat and attached it to my humidifier. The wiring is all figured out.    I was expecting the thermostat to act just like my analog humidistat,  but alas, that's not how it works.  When I try to set RH % setpoint,  it just shows some water droplet icon that ranges from 0 to 3 drops with some steps in between.    At the same time, the thermostat shows current humidity level as RH %, and it matches well with two other hygrometers in my house.   My use case is that I want to maintain a minimum steady humidity level in the winter.  In other words,  I want to set a number, for example 40%,  and have the Nest turn on the humidifier any time it drops below 40%.   Very simple.    Why does it not work that way?    At the very least,  I would like to know what is the meaning of those water droplet icons.   How do those relate to RH?  How does the thermostat decide when to enable the humidifier?    I've seen youtube videos that show older Nest thermostats with a numerical RH setpoint,  but mine doesn't have it.  So I'm in a position where I arbitrarily set some number of water droplets and pray that I get the humidity that I want.     If someone knowledgeable inside Google is listening,  can you please explain how this works?   Thanks in advance.

[dan_kle]

I think I finally found the answer.  Note that contacting Google support is useless.  They don't know this stuff.   Here's a Reddit thread that explains it:  https://www.reddit.com/r/Nest/comments/sncd2z/nest_will_show_rh_only_if_activation_is_hum_only/

In a nutshell,  the "default" setting is 35% RH.  Each step goes up or down by 5%.  The number will show up as long as "Activate" is set to "Hum. only".  Note that if it's set to "Hum. + heat", you will not see a number  (which is infuriating!),  but under the hood, the humidistat setting is still behaving (or at least appears to be behaving) the same way,  Why Google can't document this properly, so at least their own support people are aware of it is beyond comprehension.