I have no trouble Heating or cooling my caves.......they're in an area where it never freezes....never hits 80..........it's called "living in paradise???" ggg Matt Nall / Patiomatt / WCUH / Mr. DeckRug 69 Monza Cpe., 66 Monza vert, 65 Crown v8 Cpe. Somewhere between Reno, NV and Coos Bay, Or.