I'm a bit surprised and disappointed that this doesn't already exist as a Nest thermostat feature. I have my Learning thermostat set to control my whole home humidifier, but it seems there is no way to adjust the setting automatically based on outside temperature. This causes condensation to form on windows when the outside temperature drops and can lead to mold/damage to wood, etc. A simple programmable thermostat has this feature, as do most of the Nest competitors. The fact that a Nest thermostat can accomplish this without an external temp sensor could be a major selling point, since it can use local weather data!
Also, the fact that the humidity setting doesn't show up as a number is annoying as well, since you only have the ability to guess how many "droplet" symbols will feel right? This just causes you to adjust it by trial and error...
My feature request is twofold:
1) give users the option to see the actual number that the humidifier is set to instead of droplet symbols
2) Generate a curve of max humidity setting vs outdoor temperature, then allow users to offset it +/- to suit their needs (better insulated homes would be able to tolerate more humidity without condensation). When the outdoor temperature drops, the RH% setting should decrease automatically without user input. You could let advanced users generate their own curve if they wanted to, but that may be overkill. Aprilaire published a recommended curve here which could be used as a default setting: https://www.aprilaire.com/benefits/preservation/relative-humidity-chart
