Mini Split Air Conditioner / Heat pump

pnichols wrote:

time2roll wrote:
They are inherently more efficient than RV air conditioners is the biggest difference.

Huh???

Please explain.

For example ... why would a split 13.5K RV A/C be more efficient than a single package (on the roof or otherwise) 13.5K RV A/C .... especially with regards to a single package on the roof RV A/C with interior ducts distributed shooting down from the ceiling throughout the coach area?

The mini splits generally use more modern motor and compressor designs, with variable speed compressors and fans. (I think these are multiphase induction motors with variable frequency drives, usually...but that's rather immaterial). I think a good part of their better efficiency comes from being able to modulate the amount of cooling, rather than being always full-on or full-off, which I suspect lets the condenser work more efficiently--a lower coolant flow means greater cooling in the condenser, and hence more cooling for the energy input. There's no inherent reason why a traditional RV air conditioner could not incorporate many of these features, but at present they do not do so.

The fancy motors also mean that the startup current requirements are a good bit lower out of the box (i.e. without a separate soft start device). That's not an efficiency question, per se, but it is a very nice feature when running off a generator or inverter.

It also wouldn't hurt that you don't have a big hole in the ceiling with not much more than a sheet metal plate separating the evaporator and cold air from the hot outside air and motor and compressor and condenser.

RV air conditioners are among the least energy efficient ones available these days, I believe. Many window air conditioners do at least a little better. Probably most of the portable units with a hose going out a window would be even less efficient, I suspect, but that's about it.