i have a 2 stage furnace propane and a 13 seer 3 ton heatpump.live in ohio.thinking of going to a climatemaster geo. the heat pump is good down to 30. can i heat the house when it is colder in 0 to 10 deg outside.is this a good idea to go geo over what i have. my heating system is 4 years old.considering adding a zone for up and down if i do will i still need a 3 ton geo .i do plan on keeping the gas furnace and adding a desuperheater