Have HVAC Questions? Ask an HVAC Expert for Answers
If you have a heat pump, you are going to need a two stage heat,one stage cool thermostat with COOL/HEAT/and EMER HEAT as system selector.
The Honeywell RTH6350 is an excellent choice.
The RTH6350 I mentioned is a great choice. If you can provide model on both air handler and outdoor unit I will be happy to guide you in wiring the thermostat