have a fan in the lounge that has 4 setting on\off 1 fast 2 medium 3 slow
put arduino nano into place of the switch
but when it 4 deg above set point fan on fast
but when it 3 deg above set point fan on medium
but when it 1-2 deg above set point fan on slow
at set point fan off
other rule as im a kiwi 240 volts is my power
mark two version could have a little lcd display