System and Method for Evacuating a Refrigerant Leak in an HVAC System

A method of operating a heating, ventilation, and air conditioning (HVAC) system, the method comprising:

• receiving, from a first loss of charge sensor in a first refrigerant circuit, at least a first loss of charge parameter;
• determining, using a controller, that the first refrigerant circuit includes a refrigerant leak based at least upon a comparison of the first loss of charge parameter to a loss of charge threshold;
• determining, using the controller, that the HVAC system should operate in a pump down mode to evacuate the refrigerant from the first refrigerant circuit in response to determining that the first refrigerant circuit includes the refrigerant leak, wherein during the pump down mode, the method further comprises:
• operating a first compressor to increase a pressure of the refrigerant between the first compressor and a first controllable valve;
• and
• closing the first controllable valve in the first refrigerant circuit, and wherein closing the first controllable valve while operating the first compressor increases a pressure of the refrigerant between the first compressor and the first controllable valve until a predetermined pressure threshold is exceeded, and wherein the first pressure relief valve is configured upstream of the first controllable valve and downstream of the first compressor in the first refrigerant circuit.

A controller of a heating, ventilation, and air conditioning (HVAC) system, the controller comprising:

• a memory operable to store a loss of charge threshold;
• a processor operatively coupled to the memory and configured to:
• receive, from a first loss of charge sensor, at least a first loss of charge parameter;
• determine that a first refrigerant circuit includes a refrigerant leak based at least upon a comparison of the loss of charge threshold to at least the first loss of charge parameter;
• determine that the HVAC system should operate in a pump down mode to evacuate the refrigerant from the first refrigerant circuit in response to determining that the first refrigerant circuit includes the refrigerant leak, wherein during the pump down mode, the processor is further configured to:
• operate a first compressor to increase a pressure of the refrigerant between the first compressor and a first controllable valve;
• and
• close the first controllable valve in the first refrigerant circuit, and wherein closing the first controllable valve while operating the first compressor increases a pressure of the refrigerant between the first compressor and the first controllable valve until a predetermined pressure threshold is exceeded, and wherein the first pressure relief valve is configured upstream of the first controllable valve and downstream of the first compressor in the first refrigerant circuit.