I've read online that they are not that efficient. Some of them use electric heating for heat. I'm in NYC. I once used a little electric heater for a month, the electric bill was very high. I'm used to using ductless mini split, (they work great). With PTAC units, I'm kind of afraid of having an expensive bill, lackluster performance, and noise. Anyone have experience with them? This is for NYC, so heat and AC are equally as important. I wonder if they would allow me to install ductless? I haven't seen the place yet.