WIRING

TYPICAL SYSTEM WIRING TABLE

50A55

TERMINAL

SYSTEM COMPONENT

TERMINAL

TYPE

CONNECTION

W

 

low voltage thermostat W terminal (or equivalent)

G

Terminal

low voltage thermostat G terminal (or equivalent)

R

block with

low voltage thermostat R terminal (or equivalent)

Y

captive

low voltage thermostat Y terminal (or equivalent)

 

screws

(2nd wire from Y terminal goes to 24 VAC HOT side of

 

 

compressor contactor coil)

C

 

24 VAC COMMON side of compressor contactor coil

TWIN*

 

one wire twinning terminal

 

 

 

MV (2 terminals)

 

gas valve (both gas solenoids are connected in parallel)

TR

 

24 VAC transformer (low voltage COMMON side)

TH

 

24 VAC transformer (low voltage HIGH side)

RO1

 

rollout switch OUTPUT

RO2

12-pin

rollout switch INPUT

FP

connector

flame sensor probe

PS

& harness

pressure switch INPUT

PSO

 

pressure switch OUTPUT

HLI

 

high limit INPUT

HLO

 

high limit OUTPUT

GND

 

MUST BE RELIABLY GROUNDED TO CHASSIS

 

 

 

IND

2-pin

inducer HOT side

connector

IGN

ignitor HOT side

& harness

 

 

 

COOL

spade terminal

circulator blower COOL SPEED terminal

 

 

 

HEAT

spade terminal

circulator blower HEAT SPEED terminal

 

 

 

PARK (2 terminals)

spade terminal

unused circulator blower terminals

 

 

 

LINE

spade terminal

input voltage (120 VAC) HOT side

 

 

 

XFMR

spade terminal

24 VAC transformer line voltage HOT side

 

 

 

EAC (optional)

spade terminal

electronic air cleaner HOT side

 

 

 

HUM (optional)

spade terminal

humidifier HOT side

 

 

 

CIR N

spade terminal

circulator blower NEUTRAL terminal

 

 

 

LINE N

spade terminal

input voltage (120 VAC) NEUTRAL side

 

 

 

XFMR N

spade terminal

24 VAC transformer line voltage NEUTRAL side

 

 

 

EAC N (optional)

spade terminal

electronic air cleaner NEUTRAL side

 

 

 

HUM N (optional)

spade terminal

humidifier NEUTRAL side

 

 

 

IND-N

spade terminal

inducer NEUTRAL side

 

 

 

IGN-N

spade terminal

ignitor NEUTRAL side

* The twinning feature is available only on models with six screw terminals; one of these terminals will be designated “TWIN”. All 50A55 controls used in twinning applications must have the “TWIN” terminal.

Maximum recommended flame probe wire length is 36 inches.

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White Rodgers 50A55-743 installation instructions Connection, Typical System Wiring Table

50A55-743 specifications

The White Rodgers 50A55-743 is a versatile and highly efficient universal gas furnace control board widely recognized for its reliability and advanced features. Designed to enhance the performance and safety of heating systems, it caters to both residential and commercial applications, making it a preferred choice for HVAC professionals and homeowners alike.

One of the standout features of the 50A55-743 is its universal compatibility. It is designed to work with a variety of gas furnaces from different manufacturers, significantly simplifying the installation and replacement process. This feature saves time and reduces overhead costs for technicians, as they no longer have to stock multiple control boards for various furnace models.

The control board operates using advanced microprocessor technology, which ensures precise control over the heating cycle. This precision translates into optimal comfort for the occupants and can lead to significant energy savings. The board is capable of monitoring and adjusting the heating process in real-time, adapting to the specific demands of the environment.

Another important characteristic of the White Rodgers 50A55-743 is its built-in diagnostics. The board features LED indicators that provide real-time feedback on the furnace's operational status. These diagnostic lights help technicians quickly identify issues, minimizing downtime and improving service efficiency. Together with its user-friendly design, these features make troubleshooting a more straightforward process.

Safety is a paramount consideration in HVAC systems, and the 50A55-743 excels in this aspect as well. It includes multiple safety features such as flame proving, limit control, and lockout capabilities, which enhance the operational integrity of the furnace. These features help to prevent unsafe operating conditions, providing peace of mind for users.

The control board can also work with variable speed blower motors, allowing it to effectively manage airflow and heating output, leading to improved efficiency and comfort levels. Its adaptability to different configurations makes it a powerful component in modern HVAC systems.

In conclusion, the White Rodgers 50A55-743 stands out as a leading control board in the HVAC industry. With its universal compatibility, advanced microprocessor technology, built-in diagnostics, and robust safety features, it represents a significant advancement in furnace control, enhancing reliability, efficiency, and overall user satisfaction. This makes it an excellent choice for anyone looking to upgrade their heating system.