HomeKit - Add Fan Control entity for Honeywell T10 thermostat

[LoftGolf (Pete)]

Currently the HomeKit integration only allows for hvac_modes and not fan_modes to allow the ability to automate the fan setting to either: ON, CIRCULATE, or OFF.

This is a common and primary function that seemingly was overlooked but would be of great value.

[vic4news]

I believe that this is a limitation in the HomeKit api and not in the HA integration.
I created my own fan control with a Shelly relay.

Honeywell Thermostat integration without going to the cloud

At the furnace, if you connect the R and G terminals with a wire the fan will run. I used a Shelly 1 for this because the relay is separate from the voltage used to power the Shelly. The Shelly 1 is connected to 120v power, and one wire for the relay is connected to the R terminal and the other wire is connected to the G terminal. On my furnace these wires carry 24v ac power and turning on the Shelly closes the circuit and the fan runs. I created a thermostat card that has 3 fan settings. Auto…