Refrigerant leak mitigation using isolation valves

Patent metadata

Field	Value
Publication number	US-2025035356-A1
Application number	US-202418768607-A
Country	US
Kind code	A1
Filing date	Jul 10, 2024
Priority date	Jul 24, 2023
Publication date	Jan 30, 2025
Grant date	—

Abstract

A method for performing a pump down cycle to isolate an indoor section of a heating, ventilation, and air conditioning (HVAC) from an indoor section of the HVAC system is disclosed. The method includes transmitting a first control signal to a compressor of the HVAC system. The first control signal causes the compressor to turn on or stay turned on. The method further includes transmitting a second control signal to a vapor line isolation valve. The second control signal causes the vapor line isolation valve to open. The method further includes transmitting a third control signal to a liquid line isolation valve. The third control signal causes the liquid line isolation valve to close. The method further comprises determining that a refrigerant charge in the indoor section has become less than a threshold value. In response, the compressor is turned off and the vapor line isolation valve is closed.

First claim

What is claimed is:

1 . A heating, ventilation, and air conditioning (HVAC) system, the HVAC system comprising:
a vapor line isolation valve located in a vapor line of the HVAC system; a liquid line isolation valve located in a liquid line of the HVAC system; a compressor configured to move refrigerant between an indoor heat exchanger and an outdoor heat exchanger; and a controller communicatively coupled to the vapor line isolation valve, the liquid line isolation valve, and the compressor, comprising a processor configured to perform a pump down cycle comprising:
transmit, to the compressor, a first signal that causes the compressor to be turned on or stay turned on to transfer at least a portion of the refrigerant from the indoor heat exchanger to the outdoor heat exchanger to reduce a refrigerant charge in an indoor section of the HVAC system;
transmit, to the vapor line isolation valve, a second signal that causes the vapor line isolation valve to open;
transmit, to the liquid line isolation valve, a third signal that causes the liquid line isolation valve to close;
determine that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than a threshold value; and
in response to determining that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than the threshold value:
turn off the compressor; and
close the vapor line isolation valve.

2 . The HVAC system of claim 1 , wherein:
the pump down cycle is performed after a conditioning demand; and the conditioning demand is a cooling demand or a heating demand.

3 . The HVAC system of claim 1 , wherein the pump down cycle is performed during an off-cycle period when no conditioning demand is present.

4 . The HVAC system of claim 1 , wherein:
the processor is further configured to determine the refrigerant charge inside an indoor coil associated with the HVAC system; and the pump down cycle is performed when the refrigerant charge inside the indoor coil is determined to be more than the threshold value.

5 . The HVAC system of claim 4 , wherein determining the refrigerant charge inside the indoor coil comprises at least one of:
implementing a low-pressure sensor to monitor a pressure of the refrigerant inside the indoor coil; implementing a time-based control algorithm to estimate the refrigerant charge inside the indoor coil based at least in part upon an amount of time that the compressor has been turned on; or implementing an electromechanical pressure switch that is preset to a specific pressure value associated with the threshold value for the refrigerant charge.

6 . The HVAC system of claim 1 , wherein the vapor line isolation valve is positioned within the indoor section of the HVAC system.

7 . The HVAC system of claim 1 , wherein the vapor line isolation valve is positioned within an outdoor section of the HVAC system.

8 . A method of operating heating, ventilation, and air conditioning (HVAC) system, the HVAC system comprising:
performing a pump down cycle comprising:
transmitting, to a compressor, a first signal that causes the compressor to be turned on or stay turned on to transfer at least a portion of a refrigerant from an indoor heat exchanger to an outdoor heat exchanger to reduce a refrigerant charge in an indoor section of the HVAC system;
transmitting, to a vapor line isolation valve, a second signal that causes the vapor line isolation valve to open;
transmitting, to a liquid line isolation valve, a third signal that causes the liquid line isolation valve to close;
determining that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than a threshold value; and
in response to determining that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than the threshold value:
turning off the compressor; and
closing the vapor line isolation valve.

9 . The method of claim 8 , wherein:
the pump down cycle is performed after a conditioning demand; and the conditioning demand is a cooling demand or a heating demand.

10 . The method of claim 8 , wherein the pump down cycle is performed during an off-cycle period when no conditioning demand is present.

11 . The method of claim 8 , wherein:
the method further comprises determining the refrigerant charge inside an indoor coil associated with the HVAC system; and the pump down cycle is performed when the refrigerant charge inside the indoor coil is determined to be more than the threshold value.

12 . The method of claim 11 , wherein determining the refrigerant charge inside the indoor coil comprises at least one of:
implementing a low-pressure sensor to monitor a pressure of the refrigerant inside the indoor coil; implementing a time-based control algorithm to estimate the refrigerant charge inside the indoor coil based at least in part upon an amount of time that the compressor has been turned on; or implementing an electromechanical pressure switch that is preset to a specific pressure value associated with the threshold value for the refrigerant charge.

13 . The method of claim 8 , wherein the vapor line isolation valve is positioned within the indoor section of the HVAC system.

14 . The method of claim 8 , wherein the vapor line isolation valve is positioned within an outdoor section of the HVAC system.

15 . A controller of a heating, ventilation, and air conditioning (HVAC) system, the controller comprising:
a memory configured to store pump down instruction for performing a pump down cycle; and a processor communicatively coupled with the memory, and configured to:
transmit, to a compressor, a first signal that causes the compressor to be turned on or stay turned on to transfer at least a portion of a refrigerant from an indoor heat exchanger to an outdoor heat exchanger to reduce a refrigerant charge in an indoor section of the HVAC system;
transmit, to a vapor line isolation valve, a second signal that causes the vapor line isolation valve to open;
transmit, to a liquid line isolation valve, a third signal that causes the liquid line isolation valve to close;
determine that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than a threshold value; and
in response to determining that the refrigerant charge in the indoor section of the HVAC system has decreased to be less than the threshold value:
turn off the compressor; and
close the vapor line isolation valve.

16 . The controller of claim 15 , wherein:
the pump down cycle is performed after a conditioning demand; and the conditioning demand is a cooling demand or a heating demand.

17 . The controller of claim 15 , wherein the pump down cycle is performed during an off-cycle period when no conditioning demand is present.

18 . The controller of claim 15 , wherein the HVAC system is configured to operate in a cooling mode, and the vapor line isolation valve comprises a solenoid valve or a check valve.

19 . The controller of claim 15 , wherein the HVAC system is configured to operate in both a cooling mode and a heating mode, and the vapor line isolation valve comprises a solenoid valve arranged in parallel with a pressure relief valve.

20 . The controller of claim 15 , wherein:
the pump down cycle is performed after a heating cycle; and the processor is further configured to switch from a heating mode to a cooling mode before the pump down cycle is initiated.

Assignees

• Lennox Ind Inc

Inventors

• Manohar Shailesh
• Berg Eric
• Gokhale Umesh
• Sathyamurthi Vijay
• Diaz Daniel

Classifications

• F25B2600/0251

  with on-off operation · CPC title

• F25B2313/0312

  Pressure sensors near the indoor heat exchanger · CPC title

• F25B49/022 Primary

  Compressor control arrangements · CPC title

• F25B2400/19

  Pumping down refrigerant from one part of the cycle to another part of the cycle, e.g. when the cycle is changed from cooling to heating, or before a defrost cycle is started · CPC title

• F25B2600/2519

  On-off valves · CPC title