White-Rodgers 21V51U-843 Installation Manual
21V51U-843
WARNING
Failure to comply with the following
warnings could result in personal injury
or property damage.
CAUTION
Integrated Two-Stage/Variable Speed Motor
Hot Surface Ignition Control Kit
INSTALLATION INSTRUCTIONS
Operator: Save these instructions for future use!
FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE
INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL
INJURY AND/OR PROPERTY DAMAGE.
DESCRIPTION
The kit Includes:
• 50V51-843 Ignition Control Module
• 21D64-2 Ignitor Kit
• Set of Interconnect Harnesses (for Goodman)
The 50V51-843 is a two-stage automatic gas interrupted ignition
control employing a microprocessor to continually monitor,
analyze, and control the proper operation of the gas burner and
inducer. The 50V51-843 provides signals for proper operation
of a variable fan speed circulator blower.
PRECAUTIONS
Installation should be done by a qualified heating and air
conditioning contractor or licensed electrician.
If in doubt about whether your wiring is millivolt, line, or low voltage,
have it inspected by a qualified heating and air conditioning
contractor or licensed electrician.
Do not exceed the specification ratings.
All wiring must conform to local and national electrical codes
and ordinances.
This control is a precision instrument, and should be handled
carefully. Rough handling or distorting components could cause
the control to malfunction.
Following installation or replacement, follow manufacturer’s
recommended installation/service instructions to ensure proper
operation.
Do not short out terminals on gas valve or primary
control. Short or incorrect wiring may damage the
thermostat.
CONTENTS
Description ....................................................................... 1
Precautions ...................................................................... 1
Specifications ................................................................... 2
Timing Table & Definitions ................................................ 2
Installation ........................................................................ 3
Mounting & Wiring
Option Switch Settings ..................................................... 4
Mounting Hole Template ..................................................5
Wiring ..............................................................................6
Operation .........................................................................8
Troubleshooting ................................................................ 8
Signals interpreted during continual surveillance of the twostage thermostat and flame sensing element initiate automatic
ignition of the burner, sensing of the flame, and system shutoff
during normal operation.
The control incorporates system fault analysis for quick gas
flow shutoff, coupled with automatic ignition retry upon sensing
a fault correction.
FIRE HAZARD
• Do not exceed the specified voltage.
• Protect the control from direct contact with water
(dripping, spraying, rain, etc.).
• If the control has been in direct contact with water,
replace the control.
• Label all wires before disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation.
• Route and secure wiring away from flame.
SHOCK HAZARD
• Disconnect electric power before servicing.
• Ensure proper earth grounding of appliance.
• Ensure proper connection of line neutral and line
hot wires.
EXPLOSION HAZARD
• Shut off main gas to appliance until installation is
complete.
emerson.com/white-rodgers
PART NO. 37-7115001
Replaces 37-7115D
2005
SPECIFICATIONS
ELECTRICAL RATINGS [@ 77°F (25°C)]:
Input Voltage: 25 VAC, 60 Hz (Class II transformer required)
Max. Input Current @ 25 VAC: 500mA + MV
Relay Load Ratings:
Gas Valve Relays: 1.5 amps @ 25 VAC, 60 Hz
Inducer Relays: 2.2 FLA - 3.5 LRA @120 VAC
Ignitor Relay: 4.0 amps @ 120 VAC (Resistive)
Humidifier/EAC: 120 VAC/1 Amp
Flame Current Requirements:
Minimum current to insure flame detection: 0.3 µa DC*
Maximum current for non-detection: 0.1 µa DC*
Maximum allowable leakage resistance: 100 M ohms
*Measured with a DC microammeter in the flame probe lead
OPERATING TEMPERATURE RANGE:
-40° to 175°F (-40° to 80°C)
HUMIDITY RANGE:
5% to 93% relative humidity (non-condensing)
Timing Specs: (@ 60 Hz)
maximum
Flame Establishing Time: 0.8 sec
Flame Failure Response Time: 2.0 secs
Gases Approved: Natural, Manufactured, Mixed, Liquefied
Petroleum, and LP Gas Air Mixtures are all approved for use.
21V51U-843 TIMING TABLE
(All times are in seconds, unless noted otherwise)
Event Definition 50M51-843
Pre-purge Time The period of time intended to allow for the dissipation of any unburned
gas or residual products of combustion at the beginning of a furnace
operating cycle prior to initiating ignition
Igniter Warm-up Time The length of time allowed for the igniter to heat up prior to the initiation
of gas flow.
Trial for Ignition Period (TFI) The period of time between initiation of gas flow and the action to
shut off the gas flow in the event of failure to establish proof of the
supervised ignition source or the supervised main burner flame.
Ignition Activation Period (IAP) The period of time between energizing the main gas valve and
deactivation of the ignition means prior to the end of TFI
Retries The additional attempts within the same thermostat cycle for ignition
when the supervised main burner flame is not proven within the first
trial for ignition period.
Valve Sequence period Valve sequence period equals 4 seconds trial for ignition period x
(1 initial try + 2 retries) + 12 seconds.
Inter-purge The period of time intended to allow for the dissipation of any unburned
gas or residual products of combustion between the failed trial for
ignition and the retry period.
Post-purge Time The period of time intended to allow for the dissipation of any unburned
gas or residual products of combustion at the end of a furnace burner
operating cycle. Post-purge begins at the loss of flame sense.
Lock-Out Time ANSI standard rated module timing. 300
Heat Delay-To-Fan-On The period of time between proof of the supervised main burner flame
and the activation of the blower motor at Heat speed.
Heat Delay-To-Fan-Off* The period of time between the loss of a call for heat and the
deactivation of the blower motor at Heat speed.
Cool Delay-To-Fan-On The period of time after a thermostat demand for cool before
energizing the circulator blower motor at Cool speed.
Cool Delay-To-Fan-Off The period of time between the loss of a call for cool and the
deactivation of the blower motor at Cool speed.
Automatic Reset Time After one (1) hour of internal or external lockout, the control will
automatically reset itself and go into an auto restart purge for 60
seconds.
2 times
90/120/150/180
60 minutes
15
17
4
3
12
60
15
45
5
60
*These times will vary depending on option switch position.
2
INSTALLATION
DELAY
COOL
HEAT ADJ
1 2 3 4
OF
1 2 3 4
F
5 6 7 8
F
1 2 3 4
OF
GOODMAN NOTE
MOUNTING AND WIRING
All wiring should be installed according to local and national
electrical codes and ordinances.
The control must be secured to an area that will experience a
minimum of vibration and remain below the maximum ambient
temperature rating of 175°F. The control is approved for minimum
ambient temperatures of -40°F.
Any orientation is acceptable.
Refer to the wiring diagram and wiring table when connecting
the 50V51 control to other components of the system.
UL approved, 105°C rated 18 gauge min., stranded, 2/64” thick
insulation wire is recommended for all low voltage safety circuit
connections. Refer to 50V51 specification sheet for recommended
terminals to mate with those on the control.
UL approved, 105°C rated 16 gauge min., stranded, 4/64” thick
insulation wire is recommended for all line voltage connections.
Refer to 50V51 specification sheet for recommended terminals
to mate with those on the control.
LENNOX NOTE
CERTAIN CONTROLS SUCH AS P/N 100870-01 HAVE A
SPLIT IN THE OEM LIMIT CIRCUIT AND REQUIRE A MINOR
WIRING CHANGE OR THEY WILL PRODUCE A FLAME
SENSE ERROR.
CUT THE FACTORY WIRE CONNECTING TO 12-PIN MAIN
CONNECTOR PIN 3 (FLAME PROBE). SEE WIRING TABLE
ON PAGE 7.
ALL LIMITS WILL BE PROPERLY MONITORED THROUGH
PIN 11. FLAME PROBE IS CONNECTED TO ¼” SPADE FP
/ E34, UPPER LEFT OF PCB.
The 50V51-843 has only one serviceable part –an automotive
type fuse, which protects the low voltage transformer from damage if the output is short-circuited. If the fuse has opened up,
remove whatever caused the short circuit and replace the fuse
with only a 3 Amp automotive type fuse. If the fuse does not
correct the condition, replace the entire 50V51 control. There
are not other user serviceable parts.
Following installation or replacement, follow appliance manufacturer’s recommended installation or service instructions to
insure proper operation.
INSTALLER MUST READ FOR PROPER
INSTALLATION
• Wiring harnesses are included in this package to complete
the installation of the “UNIVERSAL 50V51-843” for certain
Goodman applications.
• Installer must read Option Switch Settings section and set
switches for proper control operation.
• For replacing the ignitor, a UNIVERSAL 21D64-2 is included.
For proper installation, refer to the instructions included in
the 21D64-2 kit.
• IMPORTANT: The installer may have to enlarge existing igni-
tor hole to accommodate 21D64-2 larger (.394”) diameter.
HARNESSES A & B ARE PIN TO SOCKET CONVERTERS
AND ARE ONLY USED IF THE BOARD BEING REPLACED
HAS SOCKETS.
THIS ALLOWS THE ORIGINAL FACTORY FURNACE WIRING
TO WORK WITH THE NEW 50V51-843 (21V51U-843 KIT)
WHICH HAS PINS.
OPTION SWITCH SETTINGS
MOTOR OPTIMIZATION
Amana/Goodman/Trane/Lennox/Thermo Pride – The motor
configuration DIP switches S3 and S4 must be set to match
IMPORTANT: Be sure to use proper switches for new board
settings. Switch locations on old board may not be the same
location as on the new board.
ON
SW3
F
SW4 SW3
ON
F
SW4
ON
Existing 50V51
or 50V61
OF
Switch Position
ON
50V51-843
OF
(New Board)
York – The existing board has four shunt jumper banks to set
motor function configuration. The four jumper banks are designated DELAY (E45), COOL (E43), HEAT (E46), ADJ. (E44).
Each jumper bank has four pair of pins to have jumper installed
to determine the type of voltage to the motor. These pin pairs
are A (no signal) B (positive Half-wave rectified), C (negative
Half-wave rectified), D (Full-wave unrectified).
On the new board, the motor functions must be duplicated on
DIP switched S3 and S4 per the following table.
A
B
C
D
E45
E43
A
B
C
D
E46
A
B
C
D
Jumper Banks
(Existing Board
Example Settings)
E44
3
OPTION SWITCH SETTINGS
OFF ON
OFF ON
OFF ON
1 2 3 4
ON
OF
1 2 3 4
ON
F
On the new board, the motor functions must be duplicated on
DIP switched S3 and S4 per the following table.
Motor Configuration Settings
A B C D
No Signal Positive
S4-1
OFF ON OFF ON
Half Wave
Negative
Half Wave
Full
Wave
Delay
S4-2
S3-1
OFF OFF ON ON
OFF ON OFF ON
Cool
S3-2
S4-3
OFF OFF ON ON
OFF ON OFF ON
Heat
S4-4
S3-3
OFF ON ON ON
OFF ON OFF ON
Adjust
S3-4
SW4 SW3
F
OFF OFF ON ON
Switch Position
50V51-843
(New Board
OF
Example Settings)
Multi-stage Thermostat Set-up,
Factory Default
DIP switches S7-1 and S7-2 (see table above) are set to the
“Off” position from the factory for use with a multi-stage thermostat. This allows the thermostat to control staging between
low and high fire.
Single Stage Thermostat Set-up,
Module Controls Staging
DIP switches, S7-1 and S7-2 (see table above) configure for a
single stage thermostat. Options include a 10 minute delay on
second stage, 20 minute delay on second stage or an Auto setting allowing the module to calculate the time delay for second
stage based on average demand. The “Average Calculated
Duty Cycle” table shows how the module calculates staging
based on demand.
Average
Calculated
Duty Cycle
% Equals
0 38 12 minutes Light
38 50 10 minutes Light to Average
50 62 7 minutes Average
62 75 5 minutes Average to Heavy
75 88 3 minutes Heavy Light
88 100 1 minute Heavy
or is less
than
Low to High
Stage Delay Demand
FURNACE MANUFACTURER
DIP Switch Selection for OEM Applications
S2
1 2
OFF OFF Trane
OFF ON
ON OFF Lennox
OEM
Thermo Pride/
Goodman
1
2
3
S2
ON ON Yo r k
IMPORTANT: Switch selection must match furnace manufacturer for proper motor operation.
Set DIP switches S2-1 and S2-2 to match the equipment using
the table above. NOTE: DIP switch S2-3 is not used.
THERMOSTAT TYPE AND HEAT-FAN-OFF-DELAY
DIP Switches
Switch Settings Options
Thermostat
Type and W2
Delay S7-1,
S7-2
Heat Fan Off
Delay
S7-3, S7-4
*Factory Settings
4
S7-1 S7-2 Time
Off Off Off*
On Off 10 Minutes
Off On Auto
On On 20 Minutes
S7-3 S7-4 Time
Off Off 90 Secs*
Off On 120 Secs
On Off 150 Secs
On On 180 Secs
1
2
3
4
S7
Heat Fan Off Delay Timing
DIP switches S7-3 and S7-4 (see table above) configure the
number of seconds the blower will run after the call for heat
ends. Factory default is 90 seconds.
HEAT PUMP AND DE-HUMIDIFICATION
DIP Switches
Heat Pump
S5-1
De-humidifier
S5-2
Switch
Settings
S5-1
Off Installed
On Not Installed*
S5-2
Off Installed
On Not Installed*
Options
1
2
S5
*Factory Settings
Heat Pump Systems
DIP switch S5-1 (see table above) is set to “On” from the factory
for use with conventional (non-Heat Pump systems). For heat
pump systems move the S5-1 DIP switch to the “Off” position.
This will continuously output an O signal to the motor whenever
there is Y signal and run the circulator blower at a constant speed
when the pump is operating.
De-Humidification Connection
DIP switch S5-2 (see table above) is set to “On” from the factory
for systems that do not have a dehumidification terminal connection from the thermostat. For systems using a thermostat
that provides a De-Humidification option move DIP switch S5-2
to “Off”.
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