My house came with ceiling radiant heat and no air ducts for air conditioning. We want to have a unit that can cool and heat the entire second floor. Any suggestions? I heard about systems that can be installed in an attic space. Any problems with those systems? I can't find much information on them. We were able to install a system for the 1st floor and addition, but my HVAC guy could not find an easy route for the ducts to go from the 1st floor to second floor. Thank you for any advice.