Bryant 574B manual Controls, Operating Sequence

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CONTROLS

OPERATING SEQUENCE

Heating — On a call for heating, terminal “W” of the thermostat is energized, starting the induced-draft motor. When the hall- effect sensor on the induced-draft motor senses that it has reached the required speed, the burner sequence begins. This function is performed by the integrated gas control (IGC). The evaporator fan motor is energized 45 seconds after flame is es- tablished. When the thermostat is satisfied and “W” is de- energized, the burners stop firing and the evaporator fan motor shuts off after a 45-second time-off delay.

Cooling — When the room temperature rises to a point that is slightly above the cooling control setting of the thermostat, the thermostat completes the circuit between thermostat terminal R to terminals Y and G. These completed circuits through the ther- mostat connect contactor coil (C) (through unit wire Y) and blow- er relay coil (BR) (through unit wire G) across the 24-v secondary of transformer (TRAN).

The normally open contacts of energized contactor (C) close and complete the circuit through compressor motor (COMP) to con- denser (outdoor) fan motor (OFM). Both motors start instantly.

The indoor blower will cycle on and off with a call for cooling per the on/off delay profile selected on the easy select™ circuit board.

NOTE: Once the compressor has started and then has stopped, it should not be started again until 5 minutes have elapsed.

The cooling cycle remains “on” until the room temperature drops to a point that is slightly below the cooling control setting of the room thermostat. At this point, the thermostat “breaks” the circuit between thermostat terminal R to terminals Y and G. These open circuits de-energize contactor coil C and relay coil BR. The condenser and compressor motors stop. After a 30-second de- lay, the blower motor stops. The unit is in a “standby” condition, waiting for the next “call for cooling” from the room thermostat.

The indoor blower operation with a call for fan operation (G) in cooling mode will perform by the on/off delay profile selected on the Easy Select™ circuit board.

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Contents FEATURES/BENEFITS Unit 574BEfficient Operation DURABLE, Dependable ComponentsHigh and LOW Pressure Switches provide added reli Model Number NomenclatureTable of Contents ARI* Capacities Cooling Capacities and EfficienciesARI* Capacities Heating Capacities and EfficienciesOutdoor Sound Octave Band Data Decibels LwA Range FPhysical Data Unit Size 574BPhysical Data Options and Accessories Factory-installed optionsFilter Rack Manual Outside Air Damper Base Unit Dimensions 574B024-036 Electrical Unit Weight Unit Height Center of GravityCharacteristics Base Unit Dimensions 574B042-060 Required Clearance for Operation and ServicingRequired Clearance to Combustible Matl NEC. Required ClearancesAccessory Dimensions Roof Curb DimensionsSide View Unit Size ODS Order Number574B Corner Weights Selection Procedure with ExampleSelect Unit That Corresponds to Power Source Available II Select Unit Based on Required Cooling Capacity574B024 Cooling Performance Table SHC574B030 Cooling Performance Table Performance Data Cooling Capacities574B036 Cooling Performance Table 574B042 Cooling Performance Table574B048 Cooling Performance Table 574B060 Cooling Performance TableSHC ECMFilter Pressure Drop In. wg Filter Size CFM574B Cooling DRY Coil ECM AIRFLOW-SMALL Cabinet 574B Cooling DRY Coil ECM AIRFLOW-LARGE Cabinet574B Heating ECM AIRFLOW-SMALL Cabinet 574B Heating ECM AIRFLOW-LARGE Cabinet574B ECM AIR Flow VS. Temperature Rise Chart Performance DataHigh Altitude Compensation 574B ECM WET Coil Pressure DropTypical Piping and Wiring Application Data Electrical Data 574B Standard Electrical Data Typical Wiring SCHEMATIC-208/230-1-60 Shown Typical Wiring SCHEMATIC-208/230-3-60 Shown Controls Operating SequencePage Page Guide Specifications Part 1 GeneralPart 2 Products Guide Specifications
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