Air1Supply Company
View Cart 0 item(s) / $0
HomeAbout UsContact UsPoliciesMy AccountView CartShipping
Home>HVAC Parts>Heating>Control Boards
50A55-843 WhiteRodgers $114.95 Ship Today Free Shipping
Email a friend    Review this item
50A55-843 WhiteRodgers $114.95 Ship Today Free Shipping
Item ID: 50A55-843
Availability:  
In Stock and ready to Ship Same Day
Multiple Shipping
Send to:
help
or add name:
*We'll ask for shipping info at checkout

Your Price:  
$114.95
 
Quantity
 Add to Wish List
 Description

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)

C

 

 

24 VAC COMMON side of compressor contactor coil

TWIN*

 

 

one wire twinning terminal

 

 

 

 

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

 

4-pin

inducer HOT side

IGN

 

ignitor HOT side

 

connector

IND N

 

inducer NEUTRAL side

 

& harness

 

 

 

IGN N

 

 

ignitor NEUTRAL side

 

 

 

 

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

 

 

 

 

*The twinning feature is available only on models with six screw terminals; one of these terminals will be designated “TWIN”. All 50A55-843 controls used in twinning applications must have the

“TWIN” terminal.

† Maximum recommended flame probe wire length is 36 inches.

OPERATION

OPTION SWITCHES

The option switches on the 50A55-843 control are used to determine the length of the cool delay-to-fan-off, heatdelay-to- fan-on and heat delay-to-fan-off periods. The following table shows the time periods that will result from the various switch positions.

OPTION SWITCH POSITIONS

COOL delay-

Set switch

to-fan-off:

 

#1

45 sec.*

 

On

90 sec.

 

Off

 

 

 

 

HEAT delay-

Set switch

to-fan-on:

 

#2

30 sec.*

 

On

45 sec.

 

Off

 

 

 

 

 

HEAT delay-

Set switch

to-fan-off:

#3

#4

60 sec.

On

On

90 sec.

Off

On

120 sec.

On

Off

180 sec.*

Off

Off

* Factory setting

HEAT MODE

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 humidifier are energized and the ignitor is powered within one second.

This controller has an adaptive algorithm that adjusts the dura- tion of the ignitor warm-up, to extend ignitor life. Upon initial application of power, the warm-up time is 17 seconds. The ignitor on-time will then be increased or decreased depending on whether or not flame is achieved. Thewarm-up time is limited to a maximum of 21 seconds. During the first 64 warm-up periods following power-up, thewarm-up time may not be less than 17 seconds.

Upon a call for heat, if the warm-up time has not been locked, it will be decreased by one second. This reduction of the ignitor on- time will continue until flame fails to be achieved (resulting in a retry).

In the event of a retry, the warm-up time will be increased by two seconds and locked in at that duration. Once thewarm-up time is locked, it remains fixed until another call for heat results in a retry, in which case the warm-up time is again increased by two seconds and remains locked.

In the event of two successive retry attempts, the warm-uptime will be unlocked and set to 21 seconds. If flame is then achieved, the warm-up time will begin adapting again with 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 36E manifold gas valve are opened. Flame must be detected within 4 seconds.

If flame is detected, the delay-to-fan-on period begins. After thedelay-to-fan-on period ends, the optional electronic air cleaner is energized and the circulator fan is energized at heat speed. When the thermostat is satisfied, the gas valve 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 arede-energized. After the delay-to-fan-off pe- riod ends, the circulator fan and electronic air cleaner are de- energized.

If flame is not detected, both valves are de-energized, the ignitor is turned off, and the 50A55 control goes into the “retry” se- quence. The “retry” sequence provides a60-second wait follow- ing an unsuccessful ignition attempt (flame not detected). After this wait, the ignition sequence is restarted with an additional 2 seconds of ignitor warm-uptime. If this ignition attempt is unsuccessful, one more retry will be made before the control goes into system lockout.

If flame is detected, then lost, the 50A55 control will repeat the initial ignition sequence for a total of four “recycles”. After four unsuccessful “recycle” attempts, the control will go into system lockout.

If flame is established for more than 10 seconds after ignition, the 50A55 controller will clear the ignition attempt (or retry) counter. If flame is lost after 10 seconds, it will restart the ignition sequence. This can occur a maximum of five times before system lockout.

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 begin immediately.

A momentary loss of gas supply, flame blowout, or a shorted or open condition in the flame probe circuit will be sensed within 2.0 seconds. The gas valve will de-energize and the control will restart the ignition sequence. Recycles will begin and the burner will operate normally if the gas supply returns, or the fault condition is corrected, before the last ignition attempt. Other- wise, the control will go into system lockout.

If the control has gone into system lockout, it may be possible to reset the control by a momentary power interruption of one second or longer. Refer to SYSTEM LOCKOUT FEATURES.

COOL MODE

In a typical system, a call for cool is initiated by closing 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 ener- gized, and the circulator fan is energized at cool speed. After the thermostat is satisfied, the compressor isde-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.

MANUAL FAN ON MODE

If the thermostat fan switch is moved to the ON position, the circulator fan (cool speed) and optional electronic air cleaner are energized. When the fan switch is returned to the AUTO posi- tion, the circulator fan and electronic air cleaner (optional) are de-energized.

TWINNING INTERFACE

DIAGNOSTIC FEATURES

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 expires, 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).

To enable twinning, do the following.

1.Power supplied to both furnaces must be from the same phase of the incoming 120 VAC power.

2.Connect the TWIN screw terminals on the 50A55-843 of the furnaces to be twinned to each other using a single wire (14-22 AWG.).

SYSTEM LOCKOUT AND

DIAGNOSTIC FEATURES

SYSTEM LOCKOUT FEATURES

When system lockout occurs, the gas valve is de-energized, the circulator blower is energized at heat speed, and, if flame is sensed, the inducer blower is energized. The diagnostic indica- tor light will flash or glow continuously to indicate system status.

(System lockout will never override the precautionary fea- tures.)

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 is sensed with the gas valve de-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.

3.After one hour in lockout, the control will automatically reset itself.





50A55-843 Universal Cross Reference Chart
See other side for 50A50 replacement Cross Reference

Type Number

50A55-120

50A55-143

50A55-285

50A55-286

50A55-288

50A55-438

50A55-474,

50A55-843

-571

 

 

 

 

 

 

 

Pre-Purge

15

30

0

0

0

0

0

30

Trial for Ignition

4

4

4

7

4

4

4

4

Ignition Activation

 

 

 

 

 

 

 

 

Period

1

4

4

4

1

3

1

1

Retries

4 times

4 times

2 times

2 times

2 times

2 times

2 times

2 times

Valve Sequence

 

 

 

 

 

 

 

 

Period

12

20

12

21

12

12

12

12

Interpurge

15

60

60

15

60

60

60

60

Post-Purge

5

5

15

15

15

5

5

15

Lockout Time

150

678

272

272

300

269

300

300

Heat

 

15, 30,

30

30

 

45

 

30, 45

Delay-to-Fan-On

45

45, 60

30

45

 

 

 

 

Heat

60, 90,

60, 90,

60, 90,

60, 90,

60, 90,

60, 90,

60, 100,

60, 90,

Delay-to-Fan-Off

120, 180

120, 180

120, 180

120, 180

120, 180

120, 180

140, 180

120, 180

Cool

 

 

 

 

 

 

 

 

Delay-to-Fan-On

0

0

0

0

5

2

2

5

Cool

 

 

 

 

 

 

 

 

Delay-to-Fan-Off

0

45

45

45

45

0, 80

0,,80

45, 90

Air Cleaner

 

 

 

 

 

 

 

 

terminal

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Humidifier

 

 

 

 

 

 

 

 

terminal

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Replaces

 

 

 

 

 

 

 

*

 

 

 

 

 

 

 

 

 

All times are in seconds

*The Universal 50A55-843 control will replace all 50A50 and 50A55 models

ELECTRICAL RATINGS [@ 77°F (25°C)]:

Input Voltage: 25 VAC 50/60 Hz

Max. Input Current @ 25 VAC: 0.45 amp Relay Load Ratings:

Valve Relay: 1.5 amp @ 25 VAC 50/60 Hz 0.6 pf Ignitor Relay: 6.0 amp @ 120 VAC 50/60 Hz

(resistive)

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

*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: (@ 60 Hz**)

 

 

maximum

Flame Establishing Time:

0.8 sec

Flame Failure Response Time:

2.0 sec

**At 50 Hz, all timing specifications should be increased by 20%

Gases Approved: Natural, Manufactured, Mixed, Liquified Petroleum, and LP Gas Air Mixtures are all approved for use.

TIMING SPECIFICATIONS

(All times are in seconds, unless noted otherwise)

 

50A55-843

 

 

PRE-PURGE

30

 

 

INITIAL IGNITOR WARM-UP

17

(1st 64 attempts)

 

 

 

MINIMUM IGNITOR WARM-

5

UP

 

 

 

MAXIMUM IGNITOR WARM-

21

UP

 

 

 

IGNITION ACTIVATION

1

PERIOD

 

 

 

TRIAL FOR IGNITION

4

PERIOD

 

 

 

RETRIES

2 times

 

 

VALVE SEQUENCE PERIOD

12

 

 

INTERPURGE

60

 

 

POST-PURGE

15

 

 

LOCKOUT TIME

300

 

 

HEAT DELAY-TO-FAN-ON*

30, 45

 

 

HEAT DELAY-TO-FAN-OFF*

60/90/

120/180

 

 

 

COOL DELAY-TO-FAN-ON

5

 

 

COOL DELAY-TO-FAN-OFF*

45, 90

 

 

AUTO RESET

60 minutes

 

 

HUMIDIFIER

YES

 

 

ELECTRONIC AIR CLEANER

YES

 

 

*These times will vary depending on option switch position. The control isfactory-set at 30 seconds heat delay-to-fan-on, 180 seconds heatdelay-to-fan-off and 45 seconds cooldelay-to-fan-off. See OPERATION section for further information.

TYPICAL SYSTEM WIRING DIAGRAM

HOT

(LINE)

120 VAC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TH

24 VAC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

50A55

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

COOL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HEAT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PARK

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PARK

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LINE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

XFMR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EAC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HUM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INDUCER

 

IND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IGN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HUMIDIFIER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IND N

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IGN N

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CIR N

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LINE N

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

XFMR N

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ELECTRONIC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HUM N

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EAC N

 

 

AIR CLEANER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Y

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

W

 

 

 

 

 

 

 

 

50A55-843

G

 

 

 

 

 

 

 

 

 

 

in other

 

 

 

 

 

 

 

 

furnace(s)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R

 

 

 

 

 

 

 

 

TWINNING

 

 

 

 

 

 

 

APPLICATIONS

C

 

 

 

 

 

 

 

 

 

 

 

 

ONLY

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TWIN*

TWIN*

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HLI

 

 

 

 

 

FLAME

 

 

 

 

HLO

 

 

 

 

 

SENSOR

 

 

 

 

 

 

 

 

FP

 

 

 

 

 

PROBE

RO1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RO2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MV

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MV

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LEGEND

 

 

 

 

 

 

 

 

Low Voltage (24 VAC)

 

 

 

 

 

 

 

 

 

 

 

 

 

Line Voltage (120 VAC)

 

 

 

 

 

 

 

 

 

N. C. = Normally closed switch

 

 

 

 

N. O. = Normally open switch

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NEUTRAL (LINE)

24 VAC CLASS II TRANSFORMER

TR

CIRCULATOR

BLOWER

IGNITOR

Y

WCOMPRESSOR CONTACTOR

G

R

THERMOSTAT

PRESSURE SWITCH (N. O.)

HIGH LIMIT

AUX. HIGH

(N. C.)

LIMIT (N. C.)

ROLLOUT

 

(N. C.)

GAS

 

VALV

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)

C

 

 

24 VAC COMMON side of compressor contactor coil

TWIN*

 

 

one wire twinning terminal

 

 

 

 

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

 

4-pin

inducer HOT side

IGN

 

ignitor HOT side

 

connector

IND N

 

inducer NEUTRAL side

 

& harness

 

 

 

IGN N

 

 

ignitor NEUTRAL side

 

 

 

 

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

 

 

 

 

*The twinning feature is available only on models with six screw terminals; one of these terminals will be designated “TWIN”. All 50A55-843 controls used in twinning applications must have the

“TWIN” terminal.

† Maximum recommended flame probe wire length is 36 inches.

OPERATION

OPTION SWITCHES

The option switches on the 50A55-843 control are used to determine the length of the cool delay-to-fan-off, heatdelay-to- fan-on and heat delay-to-fan-off periods. The following table shows the time periods that will result from the various switch positions.

OPTION SWITCH POSITIONS

COOL delay-

Set switch

to-fan-off:

 

#1

45 sec.*

 

On

90 sec.

 

Off

 

 

 

 

HEAT delay-

Set switch

to-fan-on:

 

#2

30 sec.*

 

On

45 sec.

 

Off

 

 

 

 

 

HEAT delay-

Set switch

to-fan-off:

#3

#4

60 sec.

On

On

90 sec.

Off

On

120 sec.

On

Off

180 sec.*

Off

Off

* Factory setting

HEAT MODE

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 humidifier are energized and the ignitor is powered within one second.

This controller has an adaptive algorithm that adjusts the dura- tion of the ignitor warm-up, to extend ignitor life. Upon initial application of power, the warm-up time is 17 seconds. The ignitor on-time will then be increased or decreased depending on whether or not flame is achieved. Thewarm-up time is limited to a maximum of 21 seconds. During the first 64 warm-up periods following power-up, thewarm-up time may not be less than 17 seconds.

Upon a call for heat, if the warm-up time has not been locked, it will be decreased by one second. This reduction of the ignitor on- time will continue until flame fails to be achieved (resulting in a retry).

In the event of a retry, the warm-up time will be increased by two seconds and locked in at that duration. Once thewarm-up time is locked, it remains fixed until another call for heat results in a retry, in which case the warm-up time is again increased by two seconds and remains locked.

In the event of two successive retry attempts, thewarm-uptime will be unlocked and set to 21 seconds. If flame is then achieved, the warm-up time will begin adapting again with 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 36E manifold gas valve are opened. Flame must be detected within 4 seconds.

If flame is detected, the delay-to-fan-on period begins. After thedelay-to-fan-on period ends, the optional electronic air cleaner is energized and the circulator fan is energized at heat speed. When the thermostat is satisfied, the gas valve 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 arede-energized. After the delay-to-fan-off pe- riod ends, the circulator fan and electronic air cleaner are de- energized.

If flame is not detected, both valves are de-energized, the ignitor is turned off, and the 50A55 control goes into the “retry” se- quence. The “retry” sequence provides a60-second wait follow- ing an unsuccessful ignition attempt (flame not detected). After this wait, the ignition sequence is restarted with an additional 2 seconds of ignitor warm-uptime. If this ignition attempt is unsuccessful, one more retry will be made before the control goes into system lockout.

If flame is detected, then lost, the 50A55 control will repeat the initial ignition sequence for a total of four “recycles”. After four unsuccessful “recycle” attempts, the control will go into system lockout.

If flame is established for more than 10 seconds after ignition, the 50A55 controller will clear the ignition attempt (or retry) counter. If flame is lost after 10 seconds, it will restart the ignition sequence. This can occur a maximum of five times before system lockout.

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 begin immediately.

A momentary loss of gas supply, flame blowout, or a shorted or open condition in the flame probe circuit will be sensed within 2.0 seconds. The gas valve will de-energize and the control will restart the ignition sequence. Recycles will begin and the burner will operate normally if the gas supply returns, or the fault condition is corrected, before the last ignition attempt. Other- wise, the control will go into system lockout.

If the control has gone into system lockout, it may be possible to reset the control by a momentary power interruption of one second or longer. Refer to SYSTEM LOCKOUT FEATURES.

COOL MODE

In a typical system, a call for cool is initiated by closing 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 ener- gized, and the circulator fan is energized at cool speed. After the thermostat is satisfied, the compressor isde-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.

MANUAL FAN ON MODE

If the thermostat fan switch is moved to the ON position, the circulator fan (cool speed) and optional electronic air cleaner are energized. When the fan switch is returned to the AUTO posi- tion, the circulator fan and electronic air cleaner (optional) are de-energized.

TWINNING INTERFACE

DIAGNOSTIC FEATURES

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 expires, 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).

To enable twinning, do the following.

1.Power supplied to both furnaces must be from the same phase of the incoming 120 VAC power.

2.Connect the TWIN screw terminals on the 50A55-843 of the furnaces to be twinned to each other using a single wire (14-22 AWG.).

SYSTEM LOCKOUT AND

DIAGNOSTIC FEATURES

SYSTEM LOCKOUT FEATURES

When system lockout occurs, the gas valve is de-energized, the circulator blower is energized at heat speed, and, if flame is sensed, the inducer blower is energized. The diagnostic indica- tor light will flash or glow continuously to indicate system status.

(System lockout will never override the precautionary fea- tures.)

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 is sensed with the gas valve de-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.

3.After one hour in lockout, the control will automatically reset itself.

The 50A55-843 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 on continuously. In this case, the entire control should be replaced, as the control is not field-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).

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

5 flashes, then pause

Open rollout switch

6 flashes, then pause

115 Volt AC power reversed/Im-

 

proper ground

7 flashes, then pause

Low flame sense signal

Continuous flashing

Flame has been sensed when

(no pause)

no flame should be present (no

 

call for heat)

The LED will also flash once at power-up.

MOUNTING HOLE TEMPLATE

MOUNTING HOLE TEMPLATE

FOR MOUNTING HOLE LOCATIONS

4.172 ± .007

(2 plcs.)

6.402 ± .010

(2 plcs.)


 Related Items
ICM316 DEFROST TIMER REPLACES TRANE $68.95
ICM316 DEFROST TIMER REPLACES TRANE $68.95
$68.95
S9200U1000 Universal Control Circuit Board $109.95 Free Same Day Shipping
S9200U1000 Universal Control Circuit Board $109.95 Free Same Day Shipping
$109.95
ICM292 $109.95 Free Shipping Replacement for Rheem 62-24140-04 Furnace Control Board
ICM292 $109.95 Free Shipping Replacement for Rheem 62-24140-04 Furnace Control Board
$109.95