Abstract: In a motor driven centrifugal compressor having a diffuser containing a movable wall for varying the width of the diffuser passage, control equipment is provided for continually changing the wall position in response to changes in motor current.

Abstract: A fluid temperature measuring device, which includes a resistance temperature detector (RTD), is disclosed for measuring the temperature of a fluid flowing through one of several heat exchange conduits which empty into a channel of a heat exchanger of a refrigeration system. The device is simple, inexpensive, reliable, easy to replace, and may be used with a microprocessor control system for the refrigeration system.

Abstract: Apparatus for satisfying heating and cooling demands including a cooling circuit having a high pressure side and a low pressure side, and a heating circuit including a booster compressor for drawing and compressing refrigerant from the high pressure side of the cooling circuit. Also disclosed is a sensor for sensing the temperature of vapor discharged from the booster compressor, and a control responsive to the sensor for terminating the heating action of the heating circuit when the temperature of vapor discharged from the booster compressor exceeds a preset value.

Abstract: A purge system for use in a refrigeration system utilizing more than one condenser, each of which operates at different pressures. The purge system includes a purge chamber having a cooling coil connected to the evaporator and adapted to condense refrigerant vapor. The purge chamber is connected to a main purge refrigerant line which includes a pressure reducing device. Either condenser in the refrigeration system is provided with a secondary purge refrigerant line connected to the main purge refrigerant line and having a one-way valve to prevent refrigerant flow from one condenser to another condenser. A pump is mounted in the system to remove the non-condensibles from the purge system. The pump is operatively connected to a pressure switch arranged between two sampling pressure lines, one of which is extending to the purge chamber and another one is extending to the main purge refrigerant line at a point ahead of the pressure reducing device.

Abstract: Apparatus for satisfying heating and cooling demands including a cooling circuit including a mechanical refrigeration unit having a low pressure side and a high pressure side, a heating circuit including a booster compressor for drawing and further compressing refrigerant from the high pressure side of the refrigeration unit, and a heat reclaiming condenser for passing the further compressed refrigerant vapor in heat transfer relation with a heat transfer fluid to heat the fluid and condense the refrigerant vapor. Also disclosed is a control for reducing the vapor flow rate through the booster compressor when the pressure in the high pressure side of the refrigeration unit falls below a predetermined value.

Abstract: Apparatus for satisfying heating and cooling demands including a cooling circuit including a mechanical refrigeration unit having a low pressure side and a high pressure side, a heating circuit including a booster compressor for drawing and further compressing refrigerant from the high pressure side of the refrigeration unit, and a heat reclaiming condenser for passing the further compressed refrigerant vapor in heat transfer relation with a heat transfer fluid to heat the fluid and condense the refrigerant vapor. Also disclosed is a control for stabilizing the vapor flow rate through the booster compressor when the pressure in the high pressure side of the refrigeration unit falls below a first predetermined value and for reducing the vapor flow rate through the booster compressor when the pressure in the high pressure side of the refrigeration unit falls below a second predetermined value less than the first predetermined value.