Emerson 50M56D-751 User Manual

50M56D-751

!

Carrier Integrated Single Stage

120V Hot Surface Ignition Control Kit

INSTALLATION INSTRUCTIONS

FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY
BEFORE INSTALLING OR OPERATING THIS CONTROL COULD CAUSE
PERSONAL INJURY AND/OR PROPERTY DAMAGE.

PARTS INCLUDED

• 50M56D-751 Integrated Furnace Control

• 2 – 1/2" Sheet Metal Screws

DESCRIPTION

• Installation Instructions

50M56D-751 is an aftermarket direct replacement
control kit for Carrier single stage furnace products with
PSC blower motors.

TWINNING: 50M56D-751 can be twinned. The other
control must also be a 50M56D-751 to ensure
proper functionality.

SPECIFICATIONS & TIMINGS

ELECTRICAL RATINGS:

Input Low Voltage: 24 VAC, 60 Hz
Input Line Voltage: 120 VAC, 60 Hz, 1φ
Max Input Current: 0.45 A @ 24 VAC
Relay Contact Ratings:

Gas Valve: 1.5 A, 0.6 PF @ 24 VAC
Ignitor Relay: 1.2 A @ 120 VAC
Inducer Relay: 2.8 A @ 120 VAC
Circulator Relay: 10 FLA, 25 LRA @ 120 VAC
Humidifier Load: 1.0 A @ 24 or 120 VAC
Electronic Air Cleaner: 1.0 A @ 120 VAC

Flame Current Requirements:

Minimum current to ensure flame detection:

0.25 μA DC*
Maximum current for non-detection: 0.1 μA DC
Maximum allowable leakage resistance:

100 M ohms
* Measured with a DC ammeter
Flame Establishing Time: 0.8 seconds maximum
Flame Failure Response Time: 2.0 seconds

maximum

OPERATING TEMPERATURE RANGE:

-40° to 176°F (-40° to 80°C)

HUMIDITY RANGE:

5 to 95% relative humidity (non-condensing)

AGENCY APPROVALS: UL USA / Canada
GASES APPROVED: Natural, Manufactured, Mixed,

Liquid Petroleum, and LP Gas Air Mixtures.

CAUTION

Risk of Electric Shock.
Disconnect electric power
to system until installation
is complete. Do not use on
circuit exceeding specified
voltage. Higher voltage will
damage control and could
cause shock or fire hazard.

This control is not
intended for use in
locations where it may
come in contact with
water.

May cause flame rollout.
Shut off main gas to
heating system until
installation is complete.

PART NO. 37-7757001

emerson.com/white-rodgers

2035

WIRING

NOTE: All wiring should be installed according to local

and national electrical codes and ordinances.

1. Disconnect electrical power and shut off gas supply
to unit, then remove unit access panels.

2. Mark and disconnect all wires from the existing
control, then remove existing control.

3. Mount 50M56D-751 in the unit following the
instructions in the Mounting section. Be certain
not to damage any components such as wire
harnesses or blower wheels when drilling or
installing screws.

4. Connect all the wires back onto the 50M56D-751
control board referencing the Wiring Diagram
section as needed.

MOUNTING

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5. Ensure all wires are secure to the control board
and unused blower speed wires are attached to
the PARK terminals. Apply wire ties as needed to
secure wiring.

6. Verify Inducer OFF / Heat ON delay, Constant Fan
Speed, and Heat OFF Delay settings, as described
in the Configuration section.

7. Reinstall unit access panels and reconnect electric
power. Restore gas supply to the unit.

8. Verify unit operation in heating, cooling, and fan
only mode.

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1

1

2

1. Slide tabs into slots in sheet metal mounting bracket.

2. Align corner holes with sheet metal holes and secure with 2 ½” screws.

NOTE: Ensure a proper ground connection is made between the control and the chassis
of the furnace. The bottom of the control board underneath screw locations should
make solid contact with clean metal on the mounting bracket and be secured firmly with
screws to ensure proper grounding and control operation.

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CONFIGURATION

Dipswitch Settings

Inducer OFF / Heat ON

(Blower) Delay (sec)

SW1-1 SW1-2 SW1- 3 & 4

5 / 45*

15 / 66

1

2

3

4

OFF

1

2

3

4

OFF OFF OFF OFF

ON ON ON ON

Constant Fan Speed Heat OFF (Blower) Delay (sec.)

LO/HEAT*

OFF OFF OFFON

FAN

1

2

3

4

ON ON ON

1

2

3

OFF

4

1

2

3

225 180

4

1

2

3

135*

4

180225

90

1

2

3

4

1

2

3

4

*Default

NOTE:

SW 1-1 selects both the inducer OFF delay and heat ON delay simultaneously. For example, the default setting
(switch ON) sets the inducer OFF delay to 5 seconds and the Heat ON delay for the blower to 45 seconds.

SELF TEST

Enter Self-Test immediately after control
power up by:

• Double pressing the “FAULT RECALL” button while
LED rapid flashes green.

NOTE: Control will terminate Self-Test mode if any
system fault occurs. Control will ignore any active
thermostat calls during Self-Test.

• Sequence is as follows:

• LED will flash all stored fault codes five times. If there
are no faults, the LED will be off for 2 seconds.

• Afterward, the LED will slowly flash code 11 in alternate

colors (green, amber, red) to indicate Self-Test is
active. This will continue until Self-Test is complete.

• Inducer motor will turn ON and continue running until
Self-Test is complete.

• After 15 seconds, the ignitor will turn ON for 15 seconds,
then OFF.

• Blower motor runs at the Fan (SW1-2), Heat, and Cool
speeds respectively for 10 seconds each.

• Blower and Inducer motors turn OFF.

• Self-Test is complete, LED will display solid green to
indicate Standby mode.

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WIRING DIAGRAM

LEGEND

LEGEND

120VAC

11 PIN FUNCTIONS

# DESCRIPTION

1

INDUCER NEUTRAL

2

IGNITOR NEUTRAL

3

IGNITOR HOT

4

INDUCER HOT

5

LIMIT OUT

6

PRESSURE IN

7

GAS VALVE COM

8

GAS VALVE OUT

9

FLAME SENSOR OUT

10

LIMIT IN

11

PRESSURE OUT

CIRCULATOR

LEGEND

LEGEND

ALS #1 Auxiliary Limit Switch - Manual Reset
ALS #2 

DSS 

LOT #1 Limit Overtemperature - Manual Reset
LOT #2 Limit Overtemperature - Manual Reset­LS Limit Switch, Overtemperature- - Auto Reset
PRS Pressure Switch

ELECTRONIC

AIR CLEANER

TRA NSFORME RTRANSFORMER

INDUCER

IGNITOR

GAS VALVE

FLAME

SENSOR

WHT

WHT

BLK

BLK

RED

ORG

BLU

BRN

WHT

RED

10

10

YEL

11

11

SEC-2 (TR)

SEC-1 (TH)

(MED LO)

(HI)

(LO)

RED

BLK

BLU

1

1

2

2

3

3

4

4

5

5

6

6

7

7

8

8

9

9

FAN

HEAT COOL

(COM)

(MED HI)

LINE 120VAC

YEL

PARK

BLK

EAC-H

(EAC-1)

PARK

PARK

BLK

LINE-H

(L1)

BLK

XFMR-H

(PR-1)

BLK

HUM-H

(120V-HUM)

HUMIDIFIER

120VAC

NEUTRAL 120VAC

WHT

L2

WHT

PR-2

EAC-2

WHT

WHT

WHT

COM PSC

NEUTRAL

NEUTRAL
NEUTRAL

TWINNING
TERMINAL

BLK

CONNECT TO

ANOTHER

(TWIN)

50M56D-751

TWINNING

HUMIDIFIER

GRY

(HUM-1)

24V HUM

24VAC

DSS

(WHEN USED)

LOT #2

(WHEN USED)

ALS #2

LOT #1

(WHEN USED)

ALS #1

LS

PRS

 FAULT RECALL PUSH BUTTON

 DIPSWITCHES

SW1-1 HEAT ON DELAY
SW1-2 FAN SPEED
SW1-3&4 HEAT OFF DELAY

 STATUS LED

YEL

RED

WHT

Y

R

W

THERMOSTAT

BLK

GRN

C

G

NOTE: The factory installed wiring harness on the 4, 12, and 16 pin connectors must remain in place for
the control to function.

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