White Rodgers 50A55-143 installation instructions Connection, Typical System Wiring Table

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)
TWIN		one wire twinning terminal
C		24 VAC COMMON side of compressor contactor coil
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
HLI		high limit INPUT
HLO		high limit OUTPUT
GND		MUST BE RELIABLY GROUNDED TO CHASSIS
(unused terminal)
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

* maximum recommended flame probe wire length is 36 inches.

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