Abstract: A throttling valve that has an outer ring unit having a plurality of superimposed cylindrical shaped outer throttling rings that define a series of annular passages between the rings. An inner ring unit also having a plurality of superimposed cylindrical shaped inner throttling rings is adapted to movably support the inner rings within the annular passages to establish elongated flow orifices between the adjacent surfaces of the rings. The geometry of each orifice is arranged so that the fluid in transit remains attached to the control surfaces of each orifice and to insure that the static pressure along the length of the orifice remains above the dynamic pressure. The tip region of each orifice is provided with a diverging flow section to further insure quiet performance along the entire length of the orifice.

Abstract: In a multizone heat pump system, individual expansion devices are provided in each of the individual refrigerant flow lines coming from the fan coils such that during the heat cycle, expansion of the refrigerant occurs in the individual expansion devices placed in the individual refrigerant flow lines rather than in a common line leading to the outdoor coil, thus preventing backup of refrigerant in any lower elevational coil(s). The expansion devices are individually sized in proportion to the relative sizes of the associated fan coils to prevent refrigerant backup in any larger fan coil(s).

Abstract: A method and apparatus for effecting capacity control of a compressor are described. A compressor having multiple capacity steps is utilized. A control valve being connected to both the compressor discharge pressure and the compressor suction pressure as well as heating and cooling pressure sensors is utilized. The control valve acts to connect appropriate pressure to the pressure sensors such that a variation in pressure level beyond a predetermined range effects a pressure sensor change indicating a need to change the capacity level of the compressor. Upon the capacity level of the compressor being changed the control valve is cycled to apply an opposite pressure level to the pressure sensor to reset the pressure sensor such that the pressure sensor may again detect a change in the pressure level to indicate a further need for a capacity change in the compressor.