Bryant R-22 System Function and Sequence of Operation, Compressor Operation, Defrost Speedup

Page 68

SYSTEM FUNCTION AND SEQUENCE OF OPERATION

NOTE: Defrost control board is equipped with 5 minute lockout timer that is initiated upon any interruption of power.

Turn on power to indoor and outdoor units. Transformer is energized.

Cooling

On a call for cooling, thermostat makes circuits R-O, R-Y, and R-G. Circuit R-O energizes reversing valve, switching it to cooling position. Circuit R-Y sends low voltage through the safeties and energizes the T1 terminal on the circuit board. If the compressor has been off for 5 minutes, or power has not been cycled for 5 minutes, the OF2 relay and T2 terminal will energize. This will close the contactor, and start the outdoor fan motor and compressor.

When the cycle is complete, R-Y is turned off, stopping the compressor and outdoor fan. The 5 minute time guard begins counting. Compressor will not come on again until this delay expires. In the event of a power interruption, the time guard will not allow another cycle for 5 minutes.

NOTE: If the indoor blower off delay is enabled, it will run up to an additional 90 seconds to increase system efficiency.

Heating

On a call for heating, thermostat makes circuits R-Y and R-G. Circuit R-Y sends low voltage through the safeties and energizes the T1 terminal on the circuit board. T1 energizes the defrost logic circuit. If the compressor has been off for 5 minutes, or power has not been cycled for 5 minutes, the OF2 relay and T2 terminal will energize. This will close the contactor, start the outdoor fan motor and compressor.

When the cycle is complete, R-Y is turned off , stopping the compressor and outdoor fan. The 5 minute time guard begins counting. Compressor will not come on again until this time delay expires. In the event of a power interruption, the time guard will not allow another cycle for 5 minutes.

Compressor Operation

The basic scroll design has been modified with the addition of an internal unloading mechanism that opens a by-pass port in the first compression pocket, effectively reducing the displacement of the scroll. The opening and closing of the by-pass port is controlled by an internal electrically operated solenoid. The modulated scroll uses a single step of unloading to go from full capacity to approximately 67% capacity.

A single speed, high efficiency motor continues to run while the scroll modulates between the two capacity steps. Modulation is achieved by venting a portion of the gas in the first suction pocket back to the low side of the compressor, thereby reducing the effective displacement of the compressor.

Full capacity is achieved by blocking these vents, thus increasing the displacement to 100%. A DC solenoid in the compressor controlled by a rectified 24 volt AC signal in the external solenoid plug moves the slider ring that covers and uncovers these vents.

The vent covers are arranged in such a manner that the compressor operates at approximately 67% capacity when the solenoid is not energized and 100% capacity when the solenoid is energized. The loading and unloading of the two step scroll is done ”on the fly” without shutting off the motor between steps.

NOTE: 67% compressor capacity translates to approximately 75% cooling or heating capacity at the indoor coil.

The compressor will always start unloaded and stay unloaded for five seconds even when the thermostat is calling for high stage capacity.

Quiet Shift

Quiet shift is a field selectable defrost mode (factory set to OFF), which will eliminate occasional noise that could be heard at the start of defrost cycle and restarting of heating cycle. It is selected by placing DIP switch 3 on defrost board (see Fig. 53) in the ON position.

When Quiet Shift switch is placed in ON position, and a defrost is initiated, the following sequence of operation will occur. Reversing valve will energize, compressor will turn off for 30 seconds, and then turn back on to complete defrost. At the start of heating after conclusion of defrost, reversing valve will de-energize, compressor will turn off for another 30 seconds, and the fan will turn off for 40 seconds, before starting in the heating mode.

Defrost

The defrost control is a time/temperature control which has field selectable settings of 30, 60, 90, or 120 minutes, factory set to 90 minutes. These settings represent the amount of time that must pass after closure of the defrost thermostat before the defrost sequence begins.

The defrost thermostat senses coil temperature throughout the heating cycle. When the coil temperature reaches the defrost thermostat setting of approximately 32 _F (0 _C), it will close, which energizes the DFT terminal and begins the defrost timing sequence. When the DFT has been energized for the selected time, the defrost cycle begins. Defrost cycle is terminated when defrost thermostat opens, or automatically after 10 minutes.

Defrost Speedup

To initiate a forced defrost, speedup pins (J1) must be shorted with a flat head screwdriver for 5 seconds and RELEASED. If the defrost thermostat is open, a short defrost cycle will be observed (actual length depends on Quiet Shift switch position). When Quiet Shift is off, only a short 30 second defrost cycle is observed. With Quiet Shift ON, the speedup sequence is one minute; 30 second compressor off period followed by 30 seconds of defrost with compressor operation. When returning to heating mode, the compressor will turn off for an additional 30 seconds and the fan for 40 seconds.

If the defrost thermostat is closed, a complete defrost cycle is initiated. If the Quiet Shift switch is turned on, the compressor will be turned off for two 30 second intervals as explained previously.

 

T2 C

 

 

 

 

 

 

 

OF1

O

C O

DFT

 

 

 

 

 

OF2

R

T1

 

 

 

 

 

 

 

 

W

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

Y

 

 

 

 

 

 

 

 

 

C

Y

 

 

 

 

 

 

 

 

SPEEDUP

P1

 

 

 

 

 

 

 

 

J1

P3

INTERVALTIMER

90

60 30

30 60

120

 

 

 

DFT

 

OFF

 

QUIET SHIFT

ON

HK32EA003

 

 

 

 

 

 

 

 

 

 

 

Speedup

 

 

 

 

Quiet

Defrost interval

 

 

Pins

 

 

 

 

Shift

DIP switches

 

 

 

 

 

 

 

 

 

 

A05378

Fig. 53 – Defrost Control

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Contents Table of Contents Application GuidelineTable of Contents TWO Stage NON-COMMUNICATING TWO Stage CommunicatingAIR Conditioner and Heat Pump Model Number Nomenclature Serial Number NomenclatureIntroduction Safety ConsiderationsInstallation Guideline Required Field-Installed Accessories for Heat Pumps AccessoriesRequired Field-Installed Accessories for Air Conditioners Accessory Descriptions Base / Mid-Tier / Deluxe 4-sided Baffle Assembly LOW-AMBIENT Cooling GuidelineDeluxe 3-sided Baffle Assembly and Dimensions Basic Cabinet Designs Cabinet AssemblyLong Line Guideline Access Compressor Or Other Internal Cabinet Components Legacy RNC and Legacy Line Control Box Identification Labeling Figure LabelsAluminum Wire ElectricalContactor CapacitorCycle Protector Time-Delay RelayCrankcase Heater Pressure Switches Personal Injury HazardDefrost Thermostat Defrost Control BoardTroubleshooting HK32EA001 If outdoor unit will not run Defrost SpeedupIf defrost thermostat is stuck closed If defrost thermostat is stuck openFive-Minute Compressor Delay Quiet ShiftCooling HeatingTroubleshooting HK32EA003 Fan MotorCompressor Plug Low-Voltage TerminalsCompressor Failures Mechanical FailuresLocked Rotor Runs, Does Not PumpNoisy Compressor Split Post Grommet part number KA75UG100Unit Personal Injury Hazard Single-Phase MotorsElectrical Failures Compressor Oil Refrigeration SystemRefrigerant Synthetic Roof Precautionary Procedure Servicing Systems on Roofs With Synthetic MaterialsBrazing Oil ChargingPersonal Injury and Unit Damage Hazard Service Valves and PumpdownPumpdown Procedure Heating Piston AccuRaterr Heat Pumps Only AccuRaterr Components Used in R-22 Heat PumpsReversing Valve Reversing Valve Heating Mode, Solenoid De-EnergizedSuction Line Filter Drier Install Liquid-line Filter Drier Indoor ACLiquid Line Filter Drier Accumulator AccumulatorInstall TXV Thermostatic Expansion Valve TXVTXV Operation Unit Operation HazardMake Piping Connections Replacing TXV on an Indoor Coil pre-2006Replacing TXV on Indoor Coil post-2006 Personal Injury and Environmental HazardRefrigeration System Repair Leak DetectionCoil Removal Fire HazardCompressor Removal and Replacement System Clean-Up After BurnoutDeep Vacuum Method Check ChargeEvacuation Troubleshooting with Superheat Basic DiagnosticsLow Superheat with Normal or Low Suction Pressure Low Superheat with High Suction PressurePseudo Evaporator Superheat Instructions High Superheat with Normal or High Suction PressureHunting Superheat Puron System Suction Pressure Drop Example22 System Suction Pressure Drop PuronrRefrigerant Pressure Temperature Chart Psig22 Refrigerant Pressure Temperature Relationship PsigPuron Subcooling Chart Liquid Line Temperature F Liq Press Subcooling F PsigPuron Superheat Chart Superheat F Psig22 Subcooling Chart Liquid Line Temperature F PT F Subcooling F Pres Psig22 Superheat Chart TWO-STAGE Application GuidelinesModel Plug Model Plug InformationGeneral Information Low Ambient CoolingDefrost Airflow Selection for 315AAV/355AAV FurnacesLiquid-Line Solenoid Accessory Defrost HoldForced Defrost All 286A units must be charged in high stage onlyOne Minute Stage Change Time Delay on 286ANA/187ANA Models Cooling and Heating OperationUtility Interface With Evolution Control Compressor Operation on 286ANA/187ANA ModelsECM Fan Motor Troubleshooting Outdoor Fan Motor OperationThermistors Time DelaysMuffler, Accumulator, Reversing Valve RVS Control BOX Troubleshooting 230V Line Power Disconnect Detection 230v Brown-Out Protection DefeatedCompressor Voltage Sensing Contactor Shorted DetectionUnloader Test Procedure Temperature ThermistorsFailed Thermistor Default Operation Thermistor Sensor ComparisonTroubleshooting Status CodesEdge Thermidistat Models T6-PRH-01 or T6-NRH-01 TWO-STAGE 286B/289B/180B/187B General Information Heating Check Chart Procedure All 286B units must be charged in high stage onlyCompressor Operation on 289B/180B Models Low Stage High Stage Low & High Model Incoming Power Troubleshooting 187B & 286B Start CircuitControl Box Contactor And CapacitorTroubleshooting HK38EA015 circuit board 286B Models Compressor Thermal Cutout 289B Compressor Thermal CutoutOutdoor Coil Thermistor OCT Attachment Status Codes Single Stage Furnace with 2-Stage Air Conditioner TWO Stage NON-COMMUNICATING 127A/226A Operating AmbientAirflow Selections ECM Furnaces Airflow Selection for FV4C Fan Coils non-communicatingDefrost Speedup System Function and Sequence of OperationCompressor Operation Check Charge Indoor Thermostat Control Options TWO Stage Communicating 167A/266AAirflow Selections for ECM Furnaces non communicating Evolution Controlled Low Ambient Cooling Defrost HoldMajor Components For Evolution Control only, Green communications Comm Light Communication and Status Function LightsOutdoor Fan Motor Operation 2230V Brown-Out Protection Defeated No 230V at Compressor Contactor Thermistor CurveOutdoor Coil Thermistor OCT Attachment 167A / 266A Troubleshooting Status CodesCare and Maintenance Final Check-Out Puronr R-410A Refrigerant Quick Reference GuideAIR Conditioner Troubleshooting Chart Heat Pump Troubleshooting Heating Cycle Heat Pump Troubleshooting Cooling Cycle Index of Tables Description Table #TWO-STAGE 286A/288A 180A/187A TWO-STAGE 286B/288B 180B/187BCatalog No. SM01---6
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R-22 specifications

The Bryant R-22 stands out in the landscape of residential heating and cooling systems with its combination of efficiency, durability, and modern technology. Designed primarily for homeowners seeking comfortable climate control solutions, the R-22 model delivers consistent performance throughout varying seasonal extremes.

One of the main features of the Bryant R-22 is its high energy efficiency. Rated with a SEER (Seasonal Energy Efficiency Ratio) that meets or exceeds industry standards, this air conditioning unit is designed to reduce energy consumption while providing optimal cooling. This not only helps in lowering monthly utility bills but also promotes environmentally responsible usage.

Another notable characteristic is the unit's durability. Constructed with a robust cabinet and high-quality components, the R-22 is built to withstand the rigors of daily use, with protective features that enhance its longevity. The cabinet comes with a powder-coated finish that resists corrosion and harsh weather conditions, ensuring that the unit stays functional and aesthetically pleasing for years.

The Bryant R-22 also incorporates advanced technology to improve user experience. One such innovation is the SmartSet technology, which allows homeowners to program their unit to optimize comfort levels according to their specific needs. This programmable capability enhances energy savings and ensures that the home remains at the desired temperature when residents are present.

Moreover, the unit features a Quiet Operating System that significantly reduces noise levels, making it suitable for residential areas where noise might be a concern. The design minimizes vibrations and optimizes airflow, creating a comfortable environment without disruptive sounds.

For added convenience, the Bryant R-22 is compatible with various thermostat options, including Wi-Fi-enabled models. This allows users to control their home's climate from anywhere using a smartphone app, facilitating effortless adjustments and monitoring of energy usage.

Finally, the Bryant R-22 is backed by a solid warranty, providing peace of mind for homeowners. This commitment to quality and customer satisfaction is a testament to Bryant’s dedication to producing reliable and efficient HVAC solutions. Overall, the Bryant R-22 is an exemplary choice for those looking to enhance their home comfort with the latest in HVAC technology.
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