Just bought a twenty year old house in Loveland, CO with an under house (crawlspace) heat pump. Original unit. Has a Lux heat pump digital thermostat. I know this unit has reached its service life. In considering replacement, I'm leaning toward a 15 SEER natural gas furnace. Can this new unit be installed in the garage? Whatever I choose to replace the old unit, I don't want it under the house! Far too difficult for me to change filter and keep unit clean. Any suggestions or tips would be greatly appreciated.

Well... it's a question that is asked often... and I say "maybe". If your existing duct work can be altered you certainly can move the furnace. You will need a heating guy to come and price it out for you. Is it feasible to move it straight up... perhaps into a closet above it's current location? Moving the furnace location will certainly make it easier to clean and service. And you certainly have gotten the life from it.