Been working on this app for awhile. If anyone would like to look through the code to see if I missed something. Been testing it not connected to the fan so far and everything seems to stage properly. I already cleaned and tested my system and have been running the fan at MedLow speed for both heat and cool for almost 2 years. The purpose of the app is 3 fold.
1 when using smart vents the fan can run at a slower speed to reduce static pressure when some of the vents are closed and keep the system efficient
2 when the fan is turned to the ON mode the fan will change to high speed to circulate air better through the house and can slow after a set time to a slower speed for all day circulation
3 when the system is trying to make a large temp change in the house the fan can speed up to high. This is for when you set a different temp when away then when home. All the smart vents should be open so the fan can run at high without raising static pressure. As the vents close and pressure raises the fan will start slowing down.
It is on my GitHub under HVAC Fan Speed Control 3. After finalizing it I will delete the other 2 versions and get reed of the 3 from its name.