characterised by the arrangement of refrigerant piping outside the heat exchanger within the unit casing

Full Title

Room units for air-conditioning, e.g. separate or self-contained units or units receiving primary air from a central station > Self-contained room units for air-conditioning, i.e. with all apparatus for treatment installed in a common casing > characterised by the arrangement of refrigerant piping outside the heat exchanger within the unit casing