Originally Posted by Missouri Bound
You have some interesting points:
If you want/need dehumidification, you need to purchase a stat which will try to dehumidify. It does this at the expense of exact temperature control. Lowering humidity is best accomplished by lowering fan speed. Hvac1000, I believe has posted a schematic where a humidistat controls the fan speed. High/low. It makes sense.
Em heat usually can be turned off and/or tied to outside temperature. The temperature set in the stat and a corresponding outdoor sensor will lockout the compressor below a certain temperature. The actual algorithm seems to be guraded among manufacturers as to when emg heat kicks in. Two ways seem plausable:
1) compressor is locked out
2) It took to long to raise the temperature
3) Difference between Setpoint and Measured Value is Large.
The adpative control algorithms in some tstats try to make the SP = to some value by the time you set, rather than change the temp at that time.
Those should not invoke emergency heat.
It is true that a very steep abrupt setback. Just changing the temperature as part of a setpoint schedule might make the energy meter spin.
One or two of the Honeywell Vision Pro stats have a dehumidification option.