White Rodgers 50A55 743 Thermostat User Manual

Home

href="
50A55-743  
Integrated Furnace Control  
INSTALLATION INSTRUCTIONS  
FAILURETO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE  
INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL  
INJURY AND/OR PROPERTY DAMAGE.  
DESCRIPTION  
The 50A55-743 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.  
These controls incorporate system fault analysis for quick  
gasowshut-off,coupledwithautomaticignitionretryupon  
sensing a fault correction.It is designed as a replacement  
for the following controls:  
Goodman  
White-Rodgers  
0130F00005  
PCBBF110  
PCBBF123  
50A55-743  
50A55-289  
50T55-289  
0130F00005S PCBBF110S PCBBF123S  
B1809926  
PCBBF112  
B1809926S  
PCBBF112S  
PRECAUTIONS  
WARNING  
Installation should be done by a qualified heating and air  
conditioning contractor or licensed electrician.  
!
Failure to comply with the following warnings could  
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.  
result in personal injury or property damage.  
FIRE HAZARD  
• Do not exceed the specified voltage.  
• Replace existing control with exact model and  
dash number.  
• Protectthecontrolfromdirectcontactwithwater  
(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.  
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 compo-  
nents could cause the control to malfunction.  
Followinginstallationorreplacement,followmanufacturer’s  
recommended installation/service instructions to ensure  
proper operation.  
• Route and secure wiring away from flame.  
SHOCK HAZARD  
• Disconnect electric power before servicing.  
• Ensure proper earth grounding of appliance.  
CAUTION  
!
• Ensure proper connection of line neutral and  
Donotshortoutterminalsongasvalveorprimary  
control. Short or incorrect wiring may damage  
the thermostat.  
line hot wires.  
EXPLOSION HAZARD  
• Shut off main gas to appliance until installation  
is complete.  
PART NO. 37-7348A  
1226  
href="
SPECIFICATIONS  
ELECTRICAL RATINGS [@ 77°F (25°C)]:  
Input Voltage: 25 VAC 50/60 Hz  
Max. Input Current @ 25 VAC: 0.45 amp  
Relay Load Ratings:  
TIMING SPECIFICATIONS  
(All times are in seconds, unless noted otherwise  
50A55-743  
Valve Relay: 1.5 amp @ 25 VAC 50/60 Hz 0.6 pf  
Ignitor Relay: 6.0 amp @ 120 VAC 50/60 Hz  
(resistive)  
Pre-Purge  
Initial Ignitor Warm-up  
(1st 64 attempts)  
Minimum Ignitor Warm-up  
Maximum Ignitor Warm-up  
Ignition Activation Period  
Trial for Ignition Period  
Retries  
15  
7
Inducer Relay: 2.2 FLA–3.5 LRA @ 120 VAC  
Circulator Relay: 14.5 FLA–25.0 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  
5
9
2
4
2 times  
*MeasuredwithaDCmicroammeterintheameprobelead  
Valve Sequence Period  
Interpurge  
Post-Purge  
12  
30  
15  
300  
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: (@ 60 Hz**)  
maximum  
Lockout Time  
Heat Delay-To-Fan-On  
Heat Delay-To-Fan-Off*  
Cool Delay-To-Fan-On  
Cool Delay-To-Fan-Off  
Auto Reset  
30  
90/120/150/180  
5
45  
Flame Establishing Time:  
Flame Failure Response Time:  
0.8 sec  
2.0 sec  
60 minutes  
Yes  
Humidifier  
Electronic Air Cleaner  
**At 50 Hz, all timing specifications should be increased  
by 20%  
Yes  
Gases Approved: Natural, Manufactured, Mixed, Liqui-  
fied Petroleum, and LP Gas Air Mixtures are all approved  
for use.  
*These times will vary depending on option switch  
position. See OPERATION section for further  
information  
INSTALLATION  
MOUNTING AND WIRING  
All wiring should be installed according to local and na-  
tional electrical codes and ordinances.  
CAUTION  
!
Donotshortoutterminalsongasvalveorprimary  
control. Short or incorrect wiring may damage  
the thermostat.  
Thecontrolmustbesecuredtoanareathatwillexperience  
a minimum of vibration and remain below the maximum  
ambient temperature rating of 175°F. The control is ap-  
proved for minimum ambient temperatures of -40°F.  
Any orientation is acceptable.  
Refertothewiringdiagramandwiringtablewhenconnect-  
ing the 50A55 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.Refer to 50A55 specification sheet for  
recommendedterminalstomatewiththoseonthecontrol.  
WARNING  
!
FIRE HAZARD  
• Do not exceed the specified voltage.  
• Replace existing control with exact model and  
dash number.  
• Protect the control from direct contact with water  
(dripping, spraying, rain, etc.).  
• If the control has been in direct contact with water,  
4/64”  
UL approved 105°C rated 16 gauge min., stranded,  
thick insulation wire is recommended for all line voltage  
connections. Refer to 50A55 specification sheet for rec-  
ommended terminals to mate with those on the control.  
After installation or replacement, follow appliance manu-  
facturer’srecommendedinstallationorserviceinstructions  
to ensure proper operation.  
replace the control.  
• Label all wires before disconnection when servic-  
ingcontrols.Wiringerrorscancauseimproperand  
dangerous operation.  
• Route and secure wiring away from flame.  
SHOCK HAZARD  
The 50A55 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 50A55 control.There are no other user  
serviceable parts.  
• 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.  
2
href="
WIRING  
TYPICAL SYSTEM WIRING DIAGRAM  
HOT  
(LINE)  
NEUTRAL  
(LINE)  
120 VAC  
24 VAC CLASS II  
TRANSFORMER  
TH  
24 VAC  
50A55  
TR  
COOL  
HEAT  
PARK  
PARK  
LINE  
XFMR  
EAC  
HUM  
IND-N  
IND  
CIRCULATOR  
BLOWER  
INDUCER  
IGNITOR  
IGN  
IGN-N  
HUMIDIFIER  
CIR N  
LINE N  
XFMR N  
HUM N  
EAC N  
ELECTRONIC  
AIR CLEANER  
Y
W
G
R
Y
W
G
R
COMPRESSOR  
CONTACTOR  
50A55  
in other  
furnace(s)  
THERMOSTAT  
TWINNING  
C
APPLICATIONS  
ONLY  
TWIN*  
TWIN*  
PRESSURE SWITCH (N. O.)  
PS  
PSO  
HLI  
HLO  
FP  
RO1  
GND  
RO2  
MV  
FLAME  
SENSOR  
PROBE  
HIGH LIMIT  
(N. C.)  
AUX. HIGH  
LIMIT (N. C.)  
ROLLOUT  
(N. C.)  
GAS  
VALVE  
MV  
TR  
TH  
LEGEND  
* 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.  
Low Voltage (24 VAC)  
Line Voltage (120 VAC)  
N. C. = Normally closed switch  
N. O. = Normally open switch  
3
href="
WIRING  
TYPICAL SYSTEM WIRING TABLE  
50A55  
TERMINAL  
TERMINAL  
SYSTEM COMPONENT  
CONNECTION  
TYPE  
W
G
R
Y
low voltage thermostat W terminal (or equivalent)  
low voltage thermostat G terminal (or equivalent)  
low voltage thermostat R terminal (or equivalent)  
low voltage thermostat Y terminal (or equivalent)  
(2nd wire from Y terminal goes to 24 VAC HOT side of  
compressor contactor coil)  
Terminal  
block with  
captive  
screws  
C
24 VAC COMMON side of compressor contactor coil  
one wire twinning terminal  
TWIN*  
MV (2 terminals)  
gas valve (both gas solenoids are connected in parallel)  
24 VAC transformer (low voltage COMMON side)  
24 VAC transformer (low voltage HIGH side)  
rollout switch OUTPUT  
TR  
TH  
RO1  
RO2  
FP  
12-pin  
rollout switch INPUT  
flame sensor probe†  
connector  
& harness  
PS  
pressure switch INPUT  
PSO  
HLI  
pressure switch OUTPUT  
high limit INPUT  
HLO  
GND  
high limit OUTPUT  
MUST BE RELIABLY GROUNDED TO CHASSIS  
2-pin  
connector  
& harness  
IND  
IGN  
inducer HOT side  
ignitor HOT side  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
spade terminal  
COOL  
circulator blower COOL SPEED terminal  
circulator blower HEAT SPEED terminal  
unused circulator blower terminals  
input voltage (120 VAC) HOT side  
24 VAC transformer line voltage HOT side  
electronic air cleaner HOT side  
humidifier HOT side  
HEAT  
PARK (2 terminals)  
LINE  
XFMR  
EAC (optional)  
HUM (optional)  
CIR N  
circulator blower NEUTRAL terminal  
input voltage (120 VAC) NEUTRAL side  
24 VAC transformer line voltage NEUTRAL side  
electronic air cleaner NEUTRAL side  
humidifier NEUTRAL side  
LINE N  
XFMR N  
EAC N (optional)  
HUM N (optional)  
IND-N  
inducer NEUTRAL side  
IGN-N  
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.  
4
href="
OPERATION  
Ifameisdetected,thedelay-to-fan-onperiodbegins.After  
thedelay-to-fan-onperiodends,theoptionalelectronicair  
cleaner is energized and the circulator fan is energized at  
heatspeed.Whenthethermostatissatisfied,thegasvalve  
is de-energized. After proof of flame loss, the heat delay-  
to-fan-off period begins and the inducer blower remains  
energized to purge the system for 15 seconds.When the  
purge is complete, the inducer blower and humidifier are  
de-energized. After the delay-to-fan-off period ends, the  
circulator fan and electronic air cleaner are de-energized.  
OPTION SWITCHES  
The option switches on the 50A55-743 control are used to  
determine the length of the heat delay-to-fan-off periods.  
The following table shows the time periods that will result  
from the various switch positions.  
OPTION SWITCH POSITIONS  
HEAT delay-  
to-fan-off:  
Set switch  
#1  
#2  
90 sec.  
120 sec.  
150 sec.**  
180 sec.  
On  
Off  
On  
Off  
On  
On  
Off  
Off  
If flame is not detected, both valves are de-energized,  
the ignitor is turned off, and the 50A55 control goes into  
the “retry” sequence. The “retry” sequence provides a  
30-secondwaitfollowinganunsuccessfulignitionattempt  
(flame not detected).After this wait, the ignition sequence  
is restarted with an additional 1 second of ignitor warm-  
up time.  
**Factory setting  
HEAT MODE  
If flame is established for more than 10 seconds after  
ignition, the50A55controllerwillcleartheignitionattempt  
(or retry) counter. If flame is lost after 10 seconds, it will  
restart the ignition sequence.  
In a typical system, a call for heat is initiated by closing  
the thermostat contacts. This starts the 50A55 control’s  
heating sequence. The inducer blower and optional hu-  
midifier are energized and the ignitor is powered after the  
15 seconds pre-purge period.  
During burner operation, a momentary loss of power of  
50 milliseconds or longer will de-energize the main gas  
valve. When power is restored, the gas valve will remain  
de-energized and a restart of the ignition sequence will  
This controller has an adaptive algorithm that adjusts  
the duration of the ignitor warm-up to extend ignitor life.  
Upon initial application of power, the warm-up time is 7 begin immediately.  
seconds. The ignitor on-time will then be increased or  
A momentary loss of gas supply, ame blowout, or a  
decreaseddependingonwhetherornotameisachieved.  
The warm-up time is limited to a maximum of 9 seconds.  
During the first 64 warm-up periods following power-up,  
the warm-up time may not be less than 5 seconds.  
shorted or open condition in the flame probe circuit will be  
sensedwithin2.0seconds.Thegasvalvewillde-energize  
andthecontrolwillrestarttheignitionsequence.Recycles  
will begin and the burner will operate normally if the gas  
Upon a call for heat, if the warm-up time has not been supply returns, or the fault condition is corrected.  
locked, it will be decreased by one second.This reduction  
If the control has gone into system lockout, it may be  
of the ignitor on-time will continue until flame fails to be  
possible to reset the control by a momentary power  
achieved (resulting in a retry).  
interruption of one second or longer. Refer to SYSTEM  
In the event of a retry, the warm-up time will be increased LOCKOUT FEATURES.  
by one second and locked in at that duration. Once the  
warm-up time is locked, it remains fixed until another call  
for heat results in a retry, in which case the warm-up time  
COOL MODE  
In a typical system, a call for cool is initiated by clos-  
ing the thermostat contacts. This energizes the 50A55  
control and the compressor. The cool delay-to-fan-on  
period begins. After the delay period ends, the optional  
electronic air cleaner is energized, and the circulator fan  
is energized at cool speed. After the thermostat is satis-  
fied, the compressor is de-energized and the cool mode  
delay-to-fan-off period begins. After the delay-to-fan-off  
period ends, the circulator fan and electronic air cleaner  
(optional) are de-energized.  
is again increased by one second and remains locked.  
Intheeventoftwosuccessiveretryattempts,thewarm-up  
time will be unlocked and set to 9 seconds.If flame is then  
achieved, thewarm-uptimewillbeginadaptingagainwith  
the next call for heat. If, however, this third attempt fails  
to achieve flame, the control will go into system lockout.  
At the end of the ignitor warm-up time, both valves in the  
gas valve are opened. Flame must be detected within 4  
seconds.  
5
href="
OPERATION  
MANUAL FAN ON MODE  
If the thermostat fan switch is moved to the ON position,  
the circulator fan (heat speed) and optional electronic air  
cleaner are energized. When the fan switch is returned  
to the AUTO position, the circulator fan and electronic air  
cleaner (optional) are de-energized.  
To reset the control after system lockout, do one of  
the following:  
1. Interrupt the call for heat or cool at the thermostat for  
at least one second but less than 20 seconds (if flame  
issensedwiththegasvalvede-energized,interrupting  
the call for heat at the thermostat will not reset the  
control).  
2. Interrupt the 24 VAC power at the control for at least  
one second. You may also need to reset the flame  
rollout sensor switch.  
TWINNING INTERFACE  
If the control has six screw terminals, one of which is  
designated TWIN, the control is equipped with a single  
wire twinning interface. If twinning is used, either control  
will process a call for heat, cool or fan as described above.  
However, after the heat-, cool-, or fan-on delay time ex-  
pires, both units will energize the circulator blowers at the  
same time.Likewise, after the heat-, cool-, or fan-off delay  
time expires, both units will de-energize the circulator  
blowers at the same time. This allows for proper air flow  
to be obtained. To assure proper control operation, both  
controls must share a common transformer ground (TR).  
3. Afteronehourinlockout, thecontrolwillautomatically  
reset itself.  
DIAGNOSTIC FEATURES  
The 50A55-743 control continuously monitors its own op-  
eration 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 field-repairable.  
To enable twinning, do the following.  
1. Power supplied to both furnaces must be from the If the sensed failure is in the system (external to the  
same phase of the incoming 120 VAC power.  
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).  
2. ConnecttheTWINscrewterminalsonthe50A55-743  
of the furnaces to be twinned to each other using a  
single wire (14-22 AWG.).  
1 flash, then pause  
System lockout  
2 flashes, then pause Pressure switch stuck closed  
3 flashes, then pause Pressure switch stuck open  
4 flashes, then pause Open limit switch  
SYSTEM LOCKOUT AND  
DIAGNOSTIC FEATURES  
5 flashes, then pause Flame has been sensed when  
no flame should be present (no  
call for heat)  
SYSTEM LOCKOUT FEATURES  
Whensystemlockoutoccurs,thegasvalveisde-energized,  
the circulator blower is energized at heat speed, and, if  
flame is sensed, the inducer blower is energized. The  
diagnostic indicator light will flash or glow continuously  
to indicate system status. (System lockout will never  
override the precautionary features.)  
6 flashes, then pause Open rollout switch  
7 flashes, then pause Low flame sense signal  
Continuous flashing  
115 Volt AC power reversed  
Control failure  
OFF  
ON  
Normal operation  
The LED will also flash once at power-up.  
6
href="
NOTES  
7
href="
White-Rodgers is a business  
of Emerson Electric Co.  
The Emerson logo is a  
trademark and service mark  
of Emerson Electric Co.  

Honeywell 69 1490 Thermostat User Manual

Honeywell RTH2310 Thermostat User Manual

White Rodgers 2.00E+158 Thermostat User Manual

White Rodgers 1F85 0471 Thermostat User Manual

White Rodgers 1F97 1277 Thermostat User Manual

White Rodgers 1F80 0261 Thermostat User Manual

Aube TH144 Thermostat User Manual

Honeywell Rth2310b Thermostat User Manual

Honeywell Q674F Thermostat User Manual

Lennox 43558 Thermostat User Manual