Thermostat wiring for separate PTAC cooling and hydronic boiler heat

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

1. 1
   Jumping Y to O at the PTAC terminals to force the reversing valve to engage whenever the compressor runs for cooling.
2. 2
   Using a Honeywell wire saver adapter to work around having only a 3-wire cable.
3. 3
   Manually moving wires around between slots depending on whether heating or cooling is needed
4. 4
   Turning the boiler switch off manually at the unit to cut power
5. 5
   Considering returning the smart thermostat and reinstalling the old one
6. 6
   Asking AI or online forums for wiring advice
7. 7
   Calling a professional installer

In their words

Unedited, most upvoted first, each linked to the thread it came from.