Can I control a heat pump and boiler heat with one thermostat?
I'm currently running such a setup with an Aprilaire 8620W thermostat.  AC from the heat pump, Heat from the heat pump when outside temp is &gt;=40F, Emergency Heat from the boiler kicks in when outside temp is &lt;40F.
The thermostat initially installed was a Honeywell model, and that could be configured to support AC, or could be configured to support Heat, but could not be configured to support both.  It took about 18 months for the contractor to figure that out (because it only became an issue at season cutovers, e.g. spring and fall; they'd fix it to whatever season was appropriate and leave without realizing the other season had been broken).  I believe the model was VisionPRO 8000 Wifi.