Lennox Industries Inc.

Lennox Manufacturing, Inc.

Lennox International Inc.

Rakesh Goel

Siddarth Rajan

Eric Berg

Mark W Olsen

Patric Ananda Balan Thobias

Eric M Perez

Vijaykumar Sathyamurthi

Shiliang Wang

Anuradha Sundararajan

Vijay Sathyamurthi

Derek Phillips

Abdul Rehman

Ian Burmania

Pete Hrejsa

Eric Quinton Giles

John Nhu Tran

Edward Robinson

Juan Antonio Contreras Lafaire

Robert B Uselton

Umesh Gokhale

Harold Gene Havard, Jr

Rosa Maria Leal

Wenqian Liu

H Gene Havard

Hermon Alan Boyd

Thomas Edward Pate, Jr

Thomas Pate

Clay Toombs

Randall Lee Lisbona

Glenn William Kowald

Jon Douglas

Peter Hrejsa

Ammar Kailani

Patric Ananda Balan

Randy Lisbona

John Tran, N

Patrie Ananda Balan

Vickey Bhardwaj

Patric Ananda Thobias

Thomas Edward Pate

A method of operating an HVAC system includes receiving a first loss of charge parameter of refrigerant from a loss of charge sensor. The method includes determining that refrigerant leak diagnostics should be performed for the HVAC system based on a comparison of the first loss of charge parameter to a loss of charge threshold. The method includes turning off a compressor in a control panel unit and a blower in an indoor unit for a predetermined wait time. The method includes receiving a measurement after the predetermined wait time that is indicative of a concentration of the refrigerant in the indoor unit from a first leak detection sensor, and receiving a measurement that is indicative of a concentration of the refrigerant in the control panel unit from a second leak detection sensor. The method includes determining a leak location of the refrigerant using a controller.

HVAC system with leak detection and method of use

A controller is configured to operate a heating, ventilation, and air conditioning (HVAC) system based on a plurality of concentration measurements received from a refrigerant detection sensor. The controller is configured to receive the plurality of concentration measurements from the refrigerant detection sensor disposed upstream of an evaporator coil. The controller is further configured to determine if a concentration of a refrigerant in a volume exceeds a stored threshold value based at least in part on the received plurality of concentration measurements. In response to determining that the concentration of refrigerant in the volume does exceed the stored threshold value, the controller is configured to operate the HVAC system in a second mode of operation, wherein the second mode of operation includes turning off a compressor and actuating a blower disposed downstream of the evaporator coil to discharge an airflow.

Refrigerant detection for a cooling system

An HVAC system includes a blower, a variable-speed compressor, an indoor air temperature sensor that measures an indoor air temperature (IAT) of an enclosed space, and a controller. The controller stores an indoor temperature setpoint and a default discharge air temperature setpoint. The controller receives the IAT. The controller determines that the IAT is not within a threshold range of the indoor temperature setpoint. The controller then determines an adaptive discharge air temperature setpoint. The controller determines a compressor speed at which to operate the variable-speed compressor based on the adaptive discharge air temperature setpoint. The controller causes the variable-speed compressor to operate at the determined compressor speed.

HVAC system operated with adaptive discharge air temperature setpoint

A refrigeration system detects a refrigerant leak by detecting that a refrigerant concentration is more than a threshold concentration. In response, the system accesses subcool, superheat, and saturation suction temperature values associated with the compressor circuits. The system determines that the subcool value is less than a subcool threshold and whether the superheat value is more than a superheat threshold. In response, the system may determine that the compressor circuit associated with the subcool and superheat values is associated with the loss of charge. In response, the system isolates the compressor circuit from other components of the system and operates a blower. The system may continue cooling operation using non-leaking compressors.

System and method for identifying a refrigerant leak in multiple refrigeration circuits with one or more compressors

An HVAC system includes a variable-speed compressor which compresses refrigerant flowing through the HVAC system, a blower which provides a flow of air through the HVAC system at a controllable flow rate, and a controller communicatively coupled to the variable-speed compressor and the blower. The controller receives a demand request, which includes a command to operate the HVAC system at a predefined setpoint temperature. In response to receiving the demand request, a setpoint temperature associated with the HVAC system can be adjusted to the predefined setpoint temperature. A speed of the variable-speed compressor is decreased to a low-speed setting. Based on the decreased speed of the variable-speed compressor, an air-flow rate can be determined to provide by the blower. The controllable flow rate of the flow of air provided by the blower can be adjusted based on the determined air-flow rate.

Peak demand response operation of HVAC systems

A method includes measuring a saturated suction temperature, receiving actual temperature value reflective of the measured saturated suction temperature, and determining whether the actual temperature value is less than a first pre-determined minimum threshold temperature value. If the actual temperature value is less than the first pre-determined minimum threshold temperature value, initiating a timer to operate for a pre-determined time interval. Determining whether the actual temperature value is less than a second pre-determined minimum threshold temperature value and if the actual temperature value is less the second pre-determined minimum threshold temperature value, initiating the timer to operate for a modified time interval. If the timer has expired, the operation of the compressor is modified.

Method and a system for preventing a freeze event using refrigerant temperature

A method of preventing evaporator coil freeze in a heating, ventilation and air conditioning (HVAC) system is performed by a controller in the HVAC system. The method includes determining a reference saturated suction temperature (SST) via a sensor disposed in relation to an evaporator coil in the HVAC system. The method also includes determining whether the reference SST is below a minimum SST threshold. The method also includes, responsive to a determination that the reference SST is below the minimum SST threshold, increasing a discharge air temperature (DAT) setpoint.

Control systems and methods for preventing evaporator coil freeze

An HVAC system includes a blower, a motor drive, and a controller. A benchmark rate of the flow of air provided by the blower and a corresponding benchmark power output of the motor drive associated with operation of the blower at a test condition are received. The controller determines a first motor drive frequency at which the motor drive is operating. Based on the benchmark rate and a comparison of the first motor drive frequency to the predefined motor drive frequency, a first rate of the flow of air provided by the blower is determined. At a later time, a current power output of the motor drive is determined during operation of the blower at the test condition. Based on a comparison of the current benchmark power output to the benchmark power output, an updated benchmark rate of the flow of air provided by the blower is determined.

Determination of blower flow rate

An HVAC system includes a compressor, condenser, and evaporator. A sensor measures a value associated with the refrigerant in the condenser or the evaporator, and a controller is communicatively coupled to the compressor and the sensor. The controller determines, based on an operational history the compressor, that pre-requisite criteria are satisfied for entering a sensor validation mode. After determining the pre-requisite criteria are satisfied, an initial sensor measurement value is determined. Following determining the initial sensor measurement value, the compressor is operated according to a sensor-validation mode. Following operating the compressor according to the sensor-validation mode for at least a minimum time, a current sensor measurement value is determined. The controller determines whether validation criteria are satisfied for the current sensor value. In response to determining that the validation criteria are satisfied, the controller determines that the sensor is validated.

Sensor validation

An HVAC system includes an evaporator. The evaporator includes a sensor configured to measure a property value (i.e., a saturated suction temperature or a saturated suction pressure) associated with saturated refrigerant flowing through the evaporator. The system includes a variable-speed compressor configured to receive the refrigerant and compress the received refrigerant. The system includes a controller communicatively coupled to the sensor and the variable-speed compressor. The controller monitors the property value measured by the sensor and detects a system fault, based on the monitored property value. In response to detecting the system fault, the controller operates the compressor in a freeze-prevention mode, which is configured to maintain the property value above a setpoint value by adjusting a speed of the variable-speed compressor.

Avoiding coil freeze in HVAC systems

A condenser coil of a system includes a subcool sensor. The subcool sensor includes a first thermistor positioned to sense a saturated liquid temperature of refrigerant flowing in a first portion of the condenser coil. The subcool sensor includes a second thermistor positioned to sense a liquid temperature of the refrigerant flowing in a second portion of the condenser coil. The second thermistor is coupled electronically in series with the first thermistor. The subcool sensor includes a signal output for transmitting a subcool signal from the subcool sensor. The signal output is coupled electronically to a first terminal of the first thermistor and a second terminal of the second thermistor. A controller of the system includes an input/output interface which receives the subcool signal from the subcool sensor and determines a temperature difference between the saturated liquid temperature and the liquid temperature based on the subcool signal.

Temperature difference sensor for HVAC systems

In an embodiment, a method of preventing evaporator coil freeze in a heating, ventilation and air conditioning (HVAC) system includes determining a reference saturated suction temperate (SST) via a sensor disposed in relation to an evaporator coil in the HVAC system, where the HVAC system is operating in reheat dehumidification mode. The method also includes determining whether the reference SST is below a minimum SST threshold. The method also includes, responsive to a determination that the reference SST is below the minimum SST threshold, determining a decreased compressor speed. The method also includes modulating a variable-speed compressor in the HVAC system in correspondence to the decreased compressor speed.

Preventing evaporator coil freeze during re-heat dehumidification

An HVAC system includes an indoor heat-exchange coil disposed between a supply air duct and a return air duct. A damper is disposed in a re-circulation duct and is moveable between an open position and a closed position. A controller is configured to determine if the HVAC system is operating in a heating mode or an air-conditioning mode. Responsive to a determination that the HVAC system is operating in the air-conditioning mode, the controller is configured to determine if the variable-speed indoor circulation fan is operating at a minimum speed and if the relative humidity measured by the humidity sensor is above a pre-determined threshold. Responsive to a determination that the variable-speed indoor circulation fan is operating at the minimum speed and the relative humidity of the enclosed space is above the pre-determined threshold, the controller signals the damper to move to the open position.

Method and system for utilizing a bypass humidifier for dehumidification during cooling

An HVAC system includes an evaporator coil disposed between a return air duct and a supply air duct. The system includes a compressor fluidically connected to the evaporator coil, and a blower for providing a flow of air through the HVAC system. A controller determines an operating mode of the HVAC system.

HVAC systems with evaporator bypass and supply air recirculation and methods of using same

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Irving, TX, United States of America

Rakesh Goel