Abstract: A method for dehumidification and controlling system pressure in a refrigeration system includes providing a refrigeration system having a compressor, a condenser and an evaporator connected in a closed refrigerant loop. Each of the condenser and evaporator have a plurality of refrigerant circuits. A first heat transfer fluid is flowed over the condenser and a second heat transfer fluid is flowed over the evaporator. At least one of the refrigerant circuits of the condenser is isolated to provide a decreased amount of heat transfer area within the condenser and to increase the refrigerant pressure within the refrigeration system when the refrigerant pressure within the refrigeration system is at or below a predetermined pressure. At least one of the refrigerant circuits of the evaporator is isolated to dehumidify and maintain the temperature of the second heat transfer fluid at or above a predetermined temperature when dehumidification is required.

Abstract: An HVAC system including a compressor, a condenser and an evaporator arrangement connected in a closed refrigerant loop. The evaporator arrangement includes a plurality of refrigerant circuits. The evaporator arrangement also includes at least one distributor configured to distribute and deliver refrigerant to each circuit of the plurality of circuits. The plurality of circuits are arranged into a first and second set of circuits. The evaporator arrangement also includes a valve configured and disposed to isolate the first set of circuits from refrigerant flow from the condenser and provide flow of refrigerant from the compressor in a dehumidification operation of the HVAC system.

Abstract: An HVAC system including a compressor, a condenser and an evaporator connected in a closed refrigerant loop. The evaporator includes a plurality of refrigerant circuits. The evaporator also includes at least one distributor configured to distribute and deliver refrigerant to each circuit of the plurality of circuits. The plurality of circuits are arranged into a first and second set of circuits. The evaporator also includes a valve configured and disposed to isolate the first set of circuits from refrigerant flow from the condenser and provide flow of refrigerant from the compressor in a dehumidification operation of the HVAC system.

Abstract: A method and system for controlling refrigerant pressure in an HVAC system. The method includes providing a compressor, a condenser and an evaporator connected in a closed refrigerant loop. The condenser has a header arrangement capable of distributing refrigerant to a plurality of refrigerant circuits within the condenser. The header arrangement also is capable of selectively isolating at least one of the circuits from refrigerant flow. Refrigerant pressure is sensed at a predetermined location in the refrigeration system. At least one of the circuits is isolated when the refrigerant pressure is less than or equal to a predetermined pressure.

Abstract: A system for defrosting an air-to-air heat pump system is disclosed. A bypass loop transfers refrigerant at a higher temperature and pressure than is normally cycled through the outdoor unit to an outdoor coil to defrost ice on the outdoor coil. The bypass loop includes a valve movable between closed and open positions. A sensor monitors a preselected condition indicative of outdoor coil performance. A controller communicates with the valve and the sensor. Once the controller determines that a preselected set point of a preselected condition indicative of deteriorating performance has been reached, the controller sends a signal to open the valve, allowing warm refrigerant to bypass expansion valves and flow to the outdoor unit to defrost the outdoor unit. Once defrosting is accomplished, the valve can be moved to a closed position to resume normal operation of the heat pump unit.