Methods to Eliminate High Pressure Surges in HVAC Systems

Abstract

A system and method are disclosed for relieving high pressure within an HVAC system. A bypass line is provided that can direct refrigerant away from an expansion device within the HVAC system. The bypass line then returns the refrigerant to the HVAC system. Other locations of bypass lines can be used as well. A controller for the HVAC system can control access to the bypass line and measure pressure within the system.

What is claimed is: 
     
         1 . An HVAC system comprising:
 an evaporator operable to receive refrigerant in a liquid or two-phase state and evaporate the refrigerant into a gaseous state;   a pressure sensor, the pressure sensor located within a liquid line of the HVAC system and operable to measure the pressure within the liquid line;   a compressor operable to receive refrigerant from the evaporator;   a condenser operable to receive refrigerant from the compressor in a gaseous state and condense the refrigerant into a liquid state;   an expansion device operable to receive refrigerant from the condenser and direct the refrigerant toward the evaporator;   a bypass line, the bypass line operable to direct refrigerant away from the expansion device and return the refrigerant to the HVAC system; and   a controller, the controller coupled to at least the pressure sensor and the bypass line, the controller operable to direct refrigerant to the bypass line when the pressure reaches a predetermined value.   
     
     
         2 . The HVAC system of  claim 1  wherein the condenser comprises a microchannel condenser. 
     
     
         3 . The HVAC system of  claim 1  further comprising a second bypass line, the second bypass line operable to direct refrigerant away from the microchannel condenser and return the refrigerant to the HVAC system. 
     
     
         4 . The HVAC system of  claim 1  further comprising a solenoid valve, the solenoid valve operable to be opened by the controller and to allow refrigerant to enter the bypass line. 
     
     
         5 . The HVAC system of  claim 1  further comprising a second pressure sensor. 
     
     
         6 . The HVAC system of  claim 1  further comprising a distributor. 
     
     
         7 . The HVAC system of  claim 1  wherein the pressure sensor is located proximate the outlet of the condenser. 
     
     
         8 . The HVAC system of  claim 3  wherein the second bypass line comprises a solenoid valve. 
     
     
         9 . A method of relieving pressure within an HVAC system comprising:
 receiving a signal to start the HVAC system;   opening a bypass line, the bypass line capable of diverting refrigerant away from an expansion valve and returning the refrigerant to the HVAC system;   starting the HVAC system; and   closing the bypass line when a predetermined event has occurred.   
     
     
         10 . The method of  claim 9  wherein the predetermined event is a period of time. 
     
     
         11 . The method of  claim 9  wherein the predetermined event is a predetermined pressure threshold. 
     
     
         12 . The method of  claim 9  wherein the HVAC system comprises a microchannel condenser. 
     
     
         13 . The method of  claim 9  wherein the bypass line comprises a pressure regulating valve. 
     
     
         14 . The method of  claim 9  wherein the bypass line comprises a solenoid valve. 
     
     
         15 . The method of  claim 9  wherein the HVAC system comprises a distributor. 
     
     
         16 . The method of  claim 9  further comprising providing a second bypass line that directs refrigerant away from the condenser and returns the refrigerant to the HVAC system. 
     
     
         17 . A method of operating an HVAC system comprising a controller, a condenser, a compressor, an evaporator, and an expansion device, the method comprising:
 receiving, at the controller, a pressure reading for the HVAC system;   opening, by the controller, a valve to a bypass line when the pressure reading exceeds a predetermined value;   wherein the bypass line directs refrigerant away from an expansion device and returns the refrigerant to the HVAC system.   
     
     
         18 . The method of  claim 17  further comprising closing the valve to the bypass line when an event has occurred. 
     
     
         19 . The method of  claim 17  the HVAC system comprises a microchannel condenser. 
     
     
         20 . The method of  claim 17  wherein the HVAC system comprises a fin tube evaporator.