I'm installing a new 5 wire progammable Hunter Thermostat. I have all but one of my wires accounted for. I RH and RC jumped together with R, W2 to W, Y to Y, and G to G. I do not need the "C" common blue wire as the new unit is battery operated, so I have this wire taped off. I have an orange wire labeled as "O" and not sure what to do with this. I know that "O" is used for reversing from heating to cooling, but not sure how to hook it up on new thermostat or if I need it. Thanks.

Is this a heat pump??

You have the wrong thermostat, you need a heat pump thermostat with two stage heat. Good luck, Mike