Abstract: An air source or water sourced packaged self-contained heat pump unit comprises indoor and outdoor sections. Heat exchangers present in these sections transfer heat between the indoor building space and the outdoor ambient. The heat exchangers are connected to form a closed loop and a compressor present in the loop pressurizes the refrigerant. A refrigerant charge control system present controls the charge of refrigerant in the main refrigerant system during heating and cooling modes. A hot-gas heat exchanger is added to the indoor section of the unit downstream of the indoor heat exchanger with respect to the airflow. Valves are used to bypass the flow of refrigerant from the compressor to the hot-gas heat exchanger during regular heating and cooling modes. In the hot-gas reheat mode, the compressed refrigerant is first directed to the hot gas heat exchanger which reheats the air to decrease the relative humidity.

Abstract: Air sourced or water sourced packaged self-contained heat pump units having indoor and outdoor sections are provided. The heat pump unit distributes its total charge of refrigerant between a main refrigerant system and a refrigerant charge control system while keeping the total charge of refrigerant in the heat pump unit constant. The refrigerant charge control system has a refrigerant reservoir, an inlet conduit, and an outlet conduit that extends into the reservoir such that its lowest point is close to the bottom of the reservoir.

Abstract: An air source or water sourced packaged self-contained heat pump unit comprises indoor and outdoor sections. Heat exchangers present in these sections transfer heat between the indoor building space and the outdoor ambient. The heat exchangers are connected to form a closed loop and a compressor present in the loop pressurizes the refrigerant. A refrigerant charge control system present controls the charge of refrigerant in the main refrigerant system during heating and cooling modes. A hot-gas heat exchanger is added to the indoor section of the unit downstream of the indoor heat exchanger with respect to the airflow. Valves are used to bypass the flow of refrigerant from the compressor to the hot-gas heat exchanger during regular heating and cooling modes. In the hot-gas reheat mode, the compressed refrigerant is first directed to the hot gas heat exchanger which reheats the air to decrease the relative humidity.