Just inherited the above trailer. It is in excellent condition inside and out with one exception. Heating does not come on. Two thermostats, Duo-Therm and Hydro Flame. Dutchmen web site no help when I contacted them. Is heating propane only? If so, how do I get it up and running? Cooling works very well. I am new to trailers and the systems but I am pretty handy and am looking for advice before I start opening up stuff or changing out.