White Rodgers 50T35-743 User manual

50T35-743
Integrated Furnace Control
FAILURETO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE
INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL
INJURY AND/OR PROPERTY DAMAGE.
DESCRIPTION
INSTALLATION INSTRUCTIONS
The 50T35-743 is an automatic gas interrupted ignition control that employs a microprocessor to continually monitor,
analyze, and control the proper operation of the gas burner, inducer, and fan. Signals interpreted during continual
surveillance of the thermostat and flame sensing element initiate automatic ignition of the burner, sensing of the
flame, and system shut-off during normal operation. This control incorporates system fault analysis for quick gas
flow shut-off, coupled with automatic ignition retry upon sensing a fault correction. It is designed as a replacement
for the following controls:
PRECAUTIONS
WARNING
Failure to comply with the following
warnings could result in personal injury
or property damage.
FIRE HAZARD
• Donotexceedthespecied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ame.
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.
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.
CAUTION
Donotshortoutterminalsongasvalveorprimary
control. Short or incorrect wiring may damage
the thermostat.
Model Replaces
White-Rodgers 50T35-730 Goodman B18099-06 Goodman B18099-13S
White-Rodgers 50T35-743 Goodman B18099-08 Goodman 1012-933D
Goodman B18099-10 Goodman 41F-5
Goodman B18099-13
www.white-rodgers.com
www.emersonclimate.com
PART NO. 37-6533C
Replaces 37-6533B
1421

2
SPECIFICATIONS
ELECTRICAL RATINGS [@ 77°F (25°C)]:
Input Voltage: 25 VAC 60 Hz
 Max.InputCurrent@25VAC:0.5 amp + MV Load
Relay Load Ratings:
Valve Relay: 1.5 amp @ 24 VAC 60 Hz 0.6 pf
Ignitor Relay: 5.0 amp @ 120 VAC 60 Hz
(resistive)
Circulator Relay: 11 FLA–26.0 LRA @ 120 VAC
Flame Current Requirements:
Minimum current to insure flame detection: 1 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)
MOUNTING:
Surface mount multipoise
Timing Specs:
maximum
Flame Establishing Time: 0.8 sec
Flame Failure Response Time: 2.0 sec
GasesApproved:Natural, Manufactured, Mixed, Liquified
Petroleum, and LP Gas Air Mixtures are all approved for use.
TimingSpecications
(All times are in seconds, unless noted otherwise)
TimingSpecication Description 50T35-743
Pre-Purge Initial delay between thermostat contact closure and trial for ignition. 15
Initial Ignitor Warm-Up Duration of ignitor warm-up time on the first 64 attempts. 15
Retry Ignitor Warm-Up Duration of ignitor warm-up time if the control retries. 20
Ignition Activation
Period
The period of time between energizing the main gas valve and
deactivation of the ignition means prior to the lockout time.
5
Trial for Ignition Period during which the valve and ignition source is activated, attempting
to ignite gas at the burner.
7
Retries Additional ignition attempts if the original ignition attempt is unsuccessful. 2 times
Valve Sequence
Period
Valve sequence period is the cumulative total amount of time that the gas
valve is energized before entering lockout.
12
Inter-Purge Period between trials for ignition when both the gas valve and ignition
source are deactivated to allow unburned gas to escape before the next
trial
30
Post-Purge After all ignition cycles are complete, the control will enter post-purge.
The combustion fan will remain on to allow unburned gas to escape. After
post-purge is complete, the combustion fan will turn off.
25/29
(90+ option)
Lockout Time 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. Reinitiating the
lighting sequence requires a manual operation if ignition is required
before Auto reset.
300
Heat Delay to Fan On Timing to allow the heat to build up in the plenum before turning on the fan. 30
Heat Delay to Fan Off Timing to allow the fan to run after the call for heat ends. This allows
residual heat to be removed from the heat exchanger and distributed to
the conditioned space.
90/120/150
Cool Delay to Fan On Timing to allow the cooling coil to cool off before turning on the fan. 5
Cool Delay to Fan Off Timing to allow the fan to run after the call for cool ends. This allows
residual cooling capacity to be removed from the cooling coils and
distributed to the conditioned space.
60
Auto Reset If shutoff occurs, the control delays for a specific recycle delay period
before beginning another trial for ignition (models with retries only).
60 minutes
*These times will vary depending on option switch position. See INSTALLATION section for further information.

3
WARNING
FIRE HAZARD
• Donotexceedthespeciedvoltage.
• Protectthecontrolfromdirectcontactwithwater
(dripping, spraying, rain, etc.).
• Labelallwiresbeforedisconnectionwhenservicing
controls. Wiring errors can cause improper and
dangerous operation.
• Routeandsecurewiringawayfromame.
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.
Donotshortoutterminalsongasvalveorprimary
control. Short or incorrect wiring may damage
the thermostat.
CAUTION
Donotshortoutterminalsongasvalveorprimary
control. Short of incorrect wiring may damage
the thermostat.
The 50T35 has only one serviceable part–an automotive
type fuse, which protects the low voltage transformer
from damage if its 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 is not the cause of the control’s problem,
replace the entire 50T35 control.There are no other user
serviceable parts.
Remove both access panels.
For GMP & GMPV series units, cut the white jumper wire
between pins 4 & 7 of the 9-pin connector.
For GMPN & GMN series units, DO NOT cut the white
jumper wire.
Remove the edgecard connector and other wires from
the existing module. Discard the thermostat wires
removed from the board (R, W & G).
Remove the existing HSI module.Care should be exercised
as not to damage the nylon standoffs.
Install the 50T35-743 module.
Reconnect the edgecard connector making sure of good
contact.
Push the 9-pin connector into the HSI module. It can go
in only one way. DO NOT force.
Reconnect the supplied thermostat wires.
Remove the red wire from the 24 volt side of the secondary
side of the transformer and discard.
Remove the blue ground wire from the transformer. DO
NOT discard.
Remove the blue wire from the transformer and discard.
Connect the red wire from the 9 pin connector on to “24
volt” of the secondary side of the transformer.
Connect the blue wire from the 9-pin connector to
“Common” terminal of the secondary side of the
transformer. This wire has a piggy back terminal.
Connect the blue ground wire, which was previously
removed, also to the “Common” terminal of the
transformer.
Replace the access panels.
Restore gas and electrical power to the furnace.
Verify the sequence of operation as noted in the furnace
manufacturer’s Installation & Operating Instructions.
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 50T35 control to other components of
the system.
UL approved, 105°C rated 18 gauge, stranded, 2/64” thick
insulation wire is recommended for all low voltage safety
circuit connections.
UL approved 105°C rated 16 gauge min., stranded, 4/64”
thick insulation wire is recommended for all line voltage
connections.
Follow the appliance manufacturer’s recommended
installation or service instructions.
INSTALLATION
Black
White
24 v. Red
Com. Blue
GND. Blue
TRANSFORMER
115v. Supply

4
INSTALLATION
SELECTING THE BLOWER OFF DELAY
In the heating mode, the blower off delay can be selected
to obtain a 90, 120 or 150 seconds period. This can be
accomplished by changing the position of the plastic
jumper located on the ignition control. See the drawing
below for the location of this jumper.
The control is factory set to give a (150) second blower
off delay. See drawing below for the jumper position for
all available settings:
Notes:
• Ifthejumperisremoved,thecontrolwilldefaulttoa
(150) second blower off delay in the heating mode.
• Theblowerontimeintheheatingmodeis(30)seconds
and is non-adjustable.
• Theblowerontimeinthecoolingmodeis(7)seconds
and is non-adjustable.
• The blower off delay in the cooling mode is (60)
seconds and is non-adjustable.
• Cautionistobeexercisednottobendthemetalpins
when changing the time delay from the factory setting.
STATUS
90
120
150
P3
JUMPER SET
STATUS
90
120
150
P3
JUMPER SET
STATUS
90
120
150
P3
JUMPER SET
FOR 90 SEC. FOR 120 SEC. FOR 150 SEC.
BLOWER
TIME OFF
JUMPER
90 120 150
STATUS
TWIN
W
G
R
DIAGNOSTIC FEATURES
The 50T35-743 control continuously monitors its own
operation and the operation of the system. If a failure
occurs, the LED will indicate a failure code as shown
below. If the failure is internal to the control, the light
willstayoff.Inthiscase,theentirecontrolshouldbe
replaced,asthecontrolisnoteld-repairable.
If the sensed failure is in the system (external to the
control), the LED will flash in the following flash-pause
sequences to indicate failure status (each flash will last
approximately 0.25 seconds, and each pause will last
approximately 2 seconds).
LED Condition
Monitored
During Action
Solid On Normal All Times None required
1 Flash Ignition
retries
exceeded
Heating
Demand
Gas Valve “Off”
Circulator
“Delay Off”
Inducer “Off”
2 Flashes PSW Stuck
Closed
Heating
Demand
Only
All Outputs
“Off” except circ
cool speed in
response to a
call for fan/cool
3 Flashes PSW Stuck
Open
Heating
Demand
Only
All Outputs
“Off” except circ
cool speed in
response to a
call for fan/cool
4 Flashes Limit
Switch
Open
Heating
Demand
Only
Gas Valve “Off”
Circulator “On”
Inducer “On”
5 Flashes Improper
Flame
All Times Gas Valve “Off”
Circulator “On”
Inducer “On”
Rapid
Flashing
Improper
Polarity
Power-up Gas Valve “Off”
Circulator “Off”
Inducer “Off”
Twinning
Fault
All other
times
Gas Valve “Off”
Circulator “Off”
Inducer “Off”
Off Internal
error
detected
All Times Gas Valve “Off”
Circulator “Off”
Inducer “Off”

5
HUM
IND
EAC
HSI
W
G
R
COOL
HEAT
NEUTRAL
TRNS
PRI
BLK
M2
M1
FS
LIMI
PSI
GV
TR
LIMO
90+0
TH
PSO
90+1
IGNITOR
R
G
W
THERMOSTAT
GAS
VALVE
HIGH LIMIT
(N. C.)
PRESSURE SWITCH (N. O.)
FLAME
SENSOR
PROBE
ELECTRONIC
AIR CLEANER
HUMIDIFIER
INDUCER
CIRCULATOR
BLOWER
50T35-743
24 VAC
120 VAC
24 VAC CLASS II
TRANSFORMER
HOT
(LINE)
NEUTRAL
(LINE)
TH TR
Low Voltage (24 VAC)
Line Voltage (120 VAC)
LEGEND
N. C. = Normally closed switch
N. O. = Normally open switch
TYPICAL SYSTEM WIRING DIAGRAM
TWIN*
TWIN*
50T35-743
in other
furnace(s)
—
TWINNING
APPLICATIONS
ONLY
*Thetwinningfeatureisavailableonlyonmodelswith
sixscrewterminals;oneoftheseterminalswillbe
designated “TWIN”. All 50T35-743 controls used in
twinningapplicationsmusthavethe“TWIN”terminal.

6
50T35
TERMINAL
TERMINAL
TYPE
SYSTEM COMPONENT
CONNECTION
TYPICAL SYSTEM WIRING TABLE
3/16" spade
terminals
3/16" spade terminals
9-pin
connector
& harness
or edge
connector
1/4" spade terminal
1/4" spade terminal
1/4" spade terminal
1/4" spade terminal
1/4" spade terminal
1/4" spade terminal
1/4" spade terminals
1/4" spade terminal
1/4" spade terminal
1/4" spade terminal
1/4" spade terminal
1/4" spade terminal
1/4" spade terminal
W
G
R
TWIN*
90+1
PSO
TH
90+0
LIMO
TR
GV
PSI
LIMO
IND
HSI
EAC
HUM
COOL
HEAT
NEUTRAL (4 terminals)
FS
M1
M2
PRI
TRNS
BLK
low voltage thermostat W terminal (or equivalent)
low voltage thermostat G terminal (or equivalent)
low voltage thermostat R terminal (or equivalent)
one wire twinning terminal
option jumper for GMP and GMPV Series Units
pressure switch OUTPUT
24 VAC transformer (low voltage HIGH side)
option jumper for GMP and GMPV Series Units
high limit OUTPUT
24 VAC transformer (low voltage COMMON side)
gas valve
pressure switch INPUT
high limit INPUT
inducer HOT side
ignitor HOT side
electronic air cleaner HOT side
humidifier HOT side
circulator blower COOL SPEED terminal
circulator blower HEAT SPEED terminal
input voltage (120 VAC) NEUTRAL side and
NEUTRAL line connections
flame sensor probe†
park
park
24 VAC transformer line voltage HOT side
24 VAC transformer line voltage NEUTRAL side
input voltage (120 VAC) HOT side
* All 50T35-743 controls used in twinning applications must have the “TWIN” terminal.
†Maximum recommended flame probe wire length is 36 inches.

7
NOTES

White-Rodgers is a business
of Emerson Electric Co.
The Emerson logo is a
trademark and service mark
of Emerson Electric Co.
www.white-rodgers.com
www.emersonclimate.com
TECHNICAL SUPPORT: 1-888-725-9797