I have a Honeywell Lyric Thermostat and a batch of Multipurpose Sensors. Many of the light switches in my home are GE, Z-Wave Switches. I would like to have my ceiling fan (GE Fan Controller) turn on when the Multipurpose Sensor upstairs shows a temperature 5 or so degrees higher than the Thermostat (the heater tends to warm the upper floor faster than the lower and I want to push the hot air down to better distribute heat and reduce heating cycles).
I have not yet found a SmartApp that uses temperature differential as a trigger. I tried IFTTT, but you can’t use SmartThings as a Trigger and an Action.