Refrigeration or heat pump installation

A refrigeration or heat pump installation that utilizes a fluid refrigerant, comprising a liquid separator having an intermediate chamber and a liquid chamber, the liquid chamber having an upper portion and a lower portion above the intermediate chamber, a compressor, a suction conduit fluidly connecting the compressor to the upper portion of the liquid chamber, a condenser, a pressure conduit connecting the condenser to the compressor, an evaporator, a third circuit for conducting fluid from the intermediate chamber to the evaporator, a fourth conduit for conducting fluid from the evaporator to the liquid chamber and control means for controlling fluid flow from the condenser to the intermediate chamber and liquid flow from the lower portion of the liquid chamber to the intermediate chamber, the control means including first switching valve means operable between an opened and a closed position for controlling the flow of fluid from the condenser to the liquid separator, second switching valve means operable between an opened and a closed position for controlling the liquid flow to the intermediate chamber and being operated in the opposite sense from the first switching valve means, the first switching valve means including an expansion valve.