I absolutely love my Pioneer 115v 12,000 BTU unit. It keeps the whole bus cool, even at 100 degrees out and no window coverings (not yet anyway). We finally had a cool morning on Sunday, so I tried the heat feature. I didn't run it very long, but it really put out the heat. It is so quiet that I literally have to walk over and feel the air to see if it's running. I still plan to install a 9000 BTU unit in the rear, but may not have to. Maybe actual use in driving, parking and using the bus will be different than it being in my driveway and working on it, but for now it's great.