Nice!! so do the heat and a/c run in parallel with each other to keep temp right at 78*? did you have to adjust the swing on each one by a couple degrees?
There is a refrigerant solenoid that turns on a reheat coil, basically another condenser right behind the evaporator. This reheats the cold air.
The cooling thermostat and heating thermostat are both set to open a solenoid prior to the TXV which lets the refrigerant flow. This raises the pressure activating a pressure switch turning on the compressor.
The temps are set 2* apart for a dead band or no run condition. At first start it is in cooling but if it drops below set point of the heat setting then the reheat coil solenoid turns on. This runs until it is between the two thermostats set points. If the humidity is above the set point then it keeps the compressor running in cooling mode. This causes the unit to keep switching back and forth between heat and cool to bring the humidity down.
When all are satisfied then the compressor shuts off.
If the temp drops too far then the aux heating thermostat turns on the electric heater to bring it back up. This is really only used in the winter as the fresh intake air can be 40* or colder. In the summer it will likely be running in cooling mode most of the time with maybe 10% heating
It took a while to figure out what all the valves, solenoids, coils and pressure reducers did on this unit. This thing has three condensers. One in line with the evaporator for reheating the air, one outdoor condenser and one refrigerant to water loop to heat the pool water.
I have it set up to dump as much heat into the pool as it can then the rest out doors. When in heating I turn off the outside condenser and only use the pool and reheat coil.
So far its holding temp within a few degrees of the set point. And keeping humidity in check. Before it would swing about 10* with factory controls and humidity was all over the place with no way to change it unless I had them reprogram it. But with as many sensors and electronics that failed it was not an option. It still needs more run time to see but so far I like it.