40” residential gas furnace operation › furnace info › 40in gas furnace operation...

1

4 0 ” R e s i d e n t i a l G a sF u r n a c e O p e r a t i o n

4 0 ” R e s i d e n t i a l G a sF u r n a c e O p e r a t i o n

• Model Evolution/Nomenclature

• Heating Sequence of Operation

• Schematics

• Ignition Systems

• Service/Troubleshooting

• Model Evolution/Nomenclature

• Heating Sequence of Operation

• Schematics

• Ignition Systems

• Service/Troubleshooting

© American Standard Inc. 1999© American Standard Inc. 1999

1

Preface

Air Conditioning and heating service techniciansmust have a working knowledge of basic electrical andrefrigeration service procedures. In order to servicegas furnaces, a thorough understanding of the unitssequence of operation is essential. This publication is

based on White-Rogers controls and provides thenarrative and schematic drawingsnecessary toprovide this understanding for thesefurnaces. Alsoincluded is a description of operating principles ofdifferent ignition systems.

Contents

Model Evolution .......................................................................................................................................................... 3

Model Nomenclature .................................................................................................................................................. 4

Component Identification – ✽ UD/✽ DD-R Models ...................................................................................................... 5

Component Identification – ✽ UY/✽ DY-R Models ....................................................................................................... 6

Integrated Furnace Controls (I.F.C.) ............................................................................................................................ 7

Self Diagnostic Features 50A50 and 50A51 ............................................................................................................... 9

Integrated Furnace Control Timing ............................................................................................................................ 10

Abnormal Furnace Operation – 50A50 and 50A51 .................................................................................................... 11

Single Stage 50A50 Sequence of Operation.............................................................................................................. 14

Wiring Schematic – Single Stage 50A50 Integrated Furnace Control ...................................................................... 15

Two Stage 50A51-405 Sequence of Operation .......................................................................................................... 16

Wiring Schematic – Two Stage Heat 50A51-405 Integrated Furnace Control ......................................................... 17

Two Stage Variable Speed Sequence Of Operation .................................................................................................. 18

Wiring Schematic – Two Stage Variable Speed 50A51-505/50A51-506 Integrated Furnace Control ..................... 19

Integrated Control Quick Reference ........................................................................................................................... 20

Furnace ECMTM2 Motor Operation ............................................................................................................................. 21

ECMTM2 Variable Speed Furnace Motor Quick Check ............................................................................................... 22

Schematic – Motor Control Board .............................................................................................................................. 24

Flame Rectification Principle – Measurement ........................................................................................................... 25

Flame Current Tester/Simulator ................................................................................................................................. 26

Combustion Air Pressure Switch Check – Measurement ......................................................................................... 27

Furnace Pressure Switch Settings .............................................................................................................................. 28

Gas Valves .................................................................................................................................................................... 29

✽ Models maybe an A or T or F continued

Note: This publication is general in nature and is intended forINSTRUCTIONAL PURPOSES ONLY. It is not to be used forequipment selection, application, installation, or specific serviceprocedures.

2

Contents – continued

Manifold Pressure Settings ......................................................................................................................................... 31

Direct Vent Manifold Pressure Check ......................................................................................................................... 32

Determining Natural Gas Furnace Input .................................................................................................................... 33

Single Stage Twinning Kit ........................................................................................................................................... 34

Field Wiring Diagrams – Single Stage and Two Stage Thermostats ....................................................................... 35

Two Stage Twinning Kit .............................................................................................................................................. 36

Fields Wiring Diagram – Twinning ✽ UD-R Furnaces ................................................................................................. 37

Single Wire Twinning – For Models with Twin Terminals ......................................................................................... 38

Radiant Sense Ignition Controls ................................................................................................................................. 39

Identifying Radiant Sense Controls ............................................................................................................................ 40

Radiant Energy Sensor ................................................................................................................................................ 41

50A52-100 Sequence of Operation ............................................................................................................................. 42

Wiring Schematic – Version 1 Radiant Sense Control .............................................................................................. 43





50A52-100/101/102 Sequence of Operation ............................................................................................................... 48


Troubleshooting Procedures ....................................................................................................................................... 50

• 50A50 Flow Chart 1 ................................................................................................................................................. 51

• 50A50 Flow Chart 2 .................................................................................................................................................. 52

• 50A50 Flow Chart 3 ................................................................................................................................................. 53

• 50A50 Flow Chart 4 ................................................................................................................................................. 54

• 50A50 Flow Chart 5 ................................................................................................................................................. 55

• 50A51 Flow Chart 1 .................................................................................................................................................. 56

• 50A51 Flow Chart 2 .................................................................................................................................................. 57

• 50A51 Flow Chart 3 .................................................................................................................................................. 58

• 50A51 Flow Chart 4 .................................................................................................................................................. 59

• 50A51 Flow Chart 5 .................................................................................................................................................. 60

• 50A52 Flow Chart 1 .................................................................................................................................................. 61

• 50A52 Flow Chart 2 .................................................................................................................................................. 62

• 50A52 Flow Chart 3 .................................................................................................................................................. 63

• 50A52 Flow Chart 4 .................................................................................................................................................. 64

Legends – System Wiring ........................................................................................................................................... 65

✽ Models maybe an A or T or F

3

40" Residential Gas Furnace Evolution

Third Quarter 1991 – ✽ UD-R and ✽ UD-C 40" induced draft upflow models introduced to replace the TUD-Blinear burner upflow models.

Second Quarter 1992 – ✽ DD-R and ✽ DD-C 40" induced draft downflow/horizontal models introduced toreplace the TDD-B linear burner downflow models and the THP, THS and THD serieshorizontal models.

Second Quarter 1993 – ✽ UE 40" single stage radiant sense ignition model introduced.

Third Quarter 1993 – ✽ UC-C and ✽ DC-C 40" condensing models introduced to replace the TUC-B and TDC-Blinear burner condensing models. (✽ UC-C models convert to horizontal left, ✽ DD-Cmodels convert to horizontal right.)

Fourth Quarter 1993 – ✽ DE 40" single stage radiant sense ignition models introduced.

Second Quarter 1994 – ✽ UX-C and ✽ DX-C 40" direct vent condensing models introduced to replace the✽ UX-B and ✽ DX-B linear burner direct vent models.

Third Quarter 1994 – TUJ-A 40" radiant sense ignition model introduced. Model converts to horizontal leftor horizontal right and is shipped without bottom panel and filter. Model discontinuedthird quarter 1995.

Fourth Quarter 1994 – ✽ UY-R-V 40" two-stage, direct vent variable speed condensing models introduced toreplace the TUC/TDC-B-V variable-speed models.

Second Quarter 1995 – ✽ DD-C-C Downflow/Horizontal and ✽ UD-C-H Upflow/Horizontal models introduced.Previous upflow models were for upflow applications only. The ✽ UD-C-H and TUE-A-Hmodels are also approved for horizontal installation. The ✽ DD-C-C and ✽ UD-C-Hmodels are equiped with the “enhanced” integrated furnace control with 120 VAChumidifier output, adaptive hot surface ignitor timing and improved fault tolerances.

First Quarter 1996 – TUE/TDE-A-K up graded to 80% AFUE. These models have remote flame rectificationignition control systems.

Fourth Quarter 1997 – Introduced the Silicon Nitride Ignitor and appropriate controls.

For all models equipped with the Silicon NitrideHot Surface Ignitor, see Pub. No. 34-3405.

✽ Models maybe an A or T or F

4

Model Nomenclature

✽ U C 0 4 0 C 9 2 4 A

Furnace ConfigurationU = Upflow U = Upflow/Horizontal D = Downflow/Horizontal

Heating Input MBTUH

Airflow Capacity for Cooling

Major Design Change

Minor Design Change

Power Supply and Fuel115 VoltNatural Gas

TypeC = Condensing – 90% AFUED = Induced Draft – 80% AFUEE = 78%/80% AFUEX = Direct Vent CondensingY = Direct Vent Condensing Variable-SpeedA = J =

18 = 1 1/2 Tons 42 = 3 1/2 Tons24 = 2 Tons 48 = 4 Tons30 = 2 1/2 Tons 60 = 5 Tons36 = 3 TonsExample: 24 MBTUH = 2 Tons

400 CFM per Ton2 Tons x 400 CFM/Ton = 800 CFM

V3 = 2 1/2 – 3 1/2 Tons, Variable Speed MotorV4 = 3 – 4 Tons, Variable Speed MotorV5 = 3 – 5 Tons, Variable Speed Motor

C = Single StageR = Two Stage

Example: 040 = 40,000 MBTUH

H = Horizontal (Upflow/Horizontal Models Only)

✽ First letter may be A or T or F

1

Product Service Change

78%/80% AFUE Cumberland}

Part I.D.

5

Component Identification – ✽ UD/ ✽ DD-R Models

✽ Models maybe an A or T

INDUCED DRAFTBLOWER (2 SPEED)

HIGH TEMPERATURELIMIT (TCO)

HIGH VOLTAGEAND ACCESSORY

HOOK-UP

FLAME ROLL-OUTMAY BE A FUSE LINK

OR A BIMETAL SWITCH

FLAME SENSOR

1ST STAGEPRESSURE SWITCH

2ND STAGEPRESSURE SWITCH

GAS VALVE(2 STAGE)

FLAME ROLL-OUTMAY BE A FUSE LINKOR A BIMETAL SWITCH

HOT SURFACEIGNITOR

INSHOT BURNER

DOOR SWITCH

INTEGRATEDFURNACE CONTROL

TRANSFORMER

DIRECT DRIVEBLOWER

REVERSE FLOWSWITCH TCO-B

6

Component Identification – ✽ UY/ ✽ DY-R Models

✽ Models maybe an A or T

HIGH TEMPERATURELIMIT SWITCH

ELECTRICALJUNCTION BOX

BURNERSIGHT GLASS

2ND STAGEPRESSURE SWITCH

1ST STAGEPRESSURE SWITCH

LINE CHOKE(NOT ON ALL MODELS)

TRANSFORMER

CONDENSATETRAP

FLAME ROLL-OUTSWITCH(MANUAL RESET)

2 STAGEGAS VALVE

INDUCED DRAFTBLOWER(2 SPEED)

TCO (LIMIT)

DOOR SWITCH

ECMTM MOTOR

IGNITIONCONTROL

ECMTM INTERFACEBOARD(MOTOR ONLY)

7

White-Rodgers Integrated Furnace Controls – 50A50 & 50A51 Series

Fan OnWhen the thermostat fan switch is in the ON position,24V AC is applied from the thermostat “G” terminalto the I.F.C. Control “G” terminal.

The “G” call to the I.F.C. control will cause it to energizean internal relay coil. This relay’s switch will close,energizing the indoor blower.

On single stage controls, the blower will run onHeating Speed. On Two-Stage I.F.C. controls, theblower will run on the low Heating Speed. OnVariable-Speed models, the “G” call to the blowermotor will signal it to run at 50% of the programmedcooling CFM speed.

Cooling Air FlowWhen the thermostat system switch is in the COOLposition and the thermostat calls for cooling, 24V ACis applied from the thermostat “Y” terminal to theI.F.C. Control “Y” terminal.

The “Y” call to the I.F.C. Control will cause it toenergize an internal relay coil. This relay switch will closeenergizing the indoor blower on the cooling speed tap.The I.F.C. control’s fan speed relays are inter-locked toprevent power from being applied to two blower motorspeed taps at the same time. On Variable-Speed models,the “Y” call to the blower motor will signal it to run at80% of the programmed cooling CFM Speed. Note:Y and BK must be jumper or humidistat connected toBK to get 100%.

If the “Y” connection is not made to the Control,the indoor blower will run on heating speed during acooling cycle.

Cooling Blower Delay to OffThe Control provides an optional indoor blower offdelay of 80 seconds in cooling cycles. The off delay isfield selectable by adjusting Dip-Switch 1 to OFFexcept 50A50-571 Control. A jumper wire must be cut.Dip-Switch 1 must be in the ON position always onvariable speed furnace models using 50A51-505/-506/-507Controls. See Furnace ECMTM2 Motor Operation.

The White-Rodgers Integrated Furnace Control (I.F.C.)is an automatic ignition control module that usesmicrocomputer based circuitry to continuously monitor,analyze and control the proper operation of the gasburner, induced draft motor and indoor blower. Themicrocomputer provides continuous surveil-lance ofthe thermostat, flame sensor and safety devices toinitiate automatic gas burner ignition and shutoffsequences during normal, or fault condition operation.

There are currently several versions of the White-Rodgers50A50/50A51 Integrated Furnace Controls:

1. 50A50 Series -405 Single-Stage controls are used in✽ UD/✽ DD-C-A, B and FCA/FUA-A-A.

2. 50A50 Series -406 Single-Stage controls are used in✽ UC/✽ DC-A & B and ✽ UX/✽ DX-C-A.

3. 50A50-471 and 473 Single-Stage used in ✽ UD-C-Hand ✽ DD-C-C.

4. 50A50-472 and 474 Single-Stage used in ✽ UC/✽ DC-C-C.

5. 50A50-571 Single-Stage used in ✽ UE/✽ DE-A-K,FUA- and FCA-E and is part of the up-gradecontrol system for Radiant Sense Controls,Part No. KIT 3793.

6. 50A51 Series -405 or -495 Two-Stage used in✽ UD/✽ DD-R.

7. 50A51-506 Two-Stage Variable-Speed used in✽ UD/✽ DD-R9V. 50A51-505 superseded by 50A51-506after October 1995.

8. 50A51-506 Two-Stage Variable-Speed used in✽ UY/✽ DY-R9V.

9. 50A51-507 Two-Stage Variable-Speed used on allVariable-Speed models after September 1996.

✽ First letter may be A or T or F

Note: Control models 50A50-406/472 and 474 and50A51-405/-495/-505/-506/-507 provide on-boardrelay switching of 120V AC system power for theoptional humidifier and electronic air cleaner accessories.Control models 50A50-471/473 provides on-boardrelay switch-ing of system power for the optionalhumidifier accessory only.

During heating cycles, the Control provides on-board relayswitching of 120V AC system power for theinduced draft motor, hot surface ignitor and 24V AC powerfor the gas valve. During heating and cooling cycles, theControl provides on-board relay switching of system powerfor the indoor blower motor.

8

E

®®

WHITE–RODGERS Emerson Electric Co.Model 50A50-571 D330927P01

REPLACE WITHCNT 2181FOR USE WITH ALL GASES

INPUT: 25VAC. 60HZ.XFMR SEC. CURRENT: 350mA + MVIGN. OUTPUT: 6.0A @ 120VAC; MV OUTPUT 1.5A @ 24VACIND. OUTPUT: 1.5 FLA, 3.0 LRA @ 120VACCIR. BLOWER OUTPUT: 14.5 FLA, 25.0 LRA @ 120VACTRIAL FOR IGNITION: 4 SEC.; PREPURGE: 0 SEC.RETRIES: 2; ATTEMPTS: 3; POSTPURGE: 5 SEC.CIR. BLOWER ON DELAY: HEAT 45 SECONDS.

HEATING OFF DELAY (SEC.)100 SEC.**COOLING OFF DELAY (SEC.)0 SEC.****FACTORY SETTING

CUT JUMPER FOR80 SEC. COOL OFFDELAY.

DISCONNECT POWERBEFORE SERVICING

-NOT FIELD REPAIRABLE-REPLACE ONLY WITH

EXACT MODEL NUMBER.EXPLOSION AND SERIOUS

INJURY COULD RESULT

156-

2822

A FLASHING SLOWFLASHING FASTCONTINUOUS ONCONTINUOUS OFF2 FLASHES3 FLASHES4 FLASHES5 FLASHES

DIAGNOSTIC INDICATORNORMAL. NO CALL FOR HEATNORMAL. CALL FOR HEATINTERNAL CONTROL FAILURE (REPLACE)NO POWER OR CONTROL FAILURESYSTEM LOCKOUT (NO FLAME) CHECK LINE POLARITYPRESSURE SWITCH PROBLEMTHERMAL PROTECTION DEVICE OPENFLAME SENSED WITH GAS VALVE OFF

REFER TO SERVICE INSTRUCTIONS FOR MORE INFORMATION

TH FP HLO

TR

MV GND HLI

MV PS

CIRCULATOR BLOWER

COOL

HEAT

PARK

PARK

LINE

XFM

R

TP CIR

IGN LINE

XFM

R

IND INDNIGNN

HOT 120VAC NEUTRAL 120VAC

CG

RW

Y

ClipWire

153-

6148

® ®

DIAGNOSTIC INDICATORFLASHING SLOWFLASHING FASTCONTINUOUS ONCONTINUOUS OFF2 FLASHES3 FLASHES4 FLASHES5 FLASHES

NORMAL. NO CALL FOR HEATNORMAL CALL FOR HEATREPLACE CONTROLCHECK POWERSYSTEM LOCKOUT (NO FLAME)PRESSURE SWITCH PROBLEMTHERMAL PROTECTION DEVICE OPENFLAME SENSED WITH GAS VALVE OFF

REFER TO SERVICE INSTRUCTIONS FOR MORE INFORMATION

UT: 1.5A @ 25 VACC20 VACA @ 120VAC

GE: 0 SEC.E: 5 SEC.

5 D340021P01REPLACE WITH

CNT1308

Emerson Electric Co.RS

Heating Blower On and Off DelayThese controls provide a fixed 45 second indoor “bloweron” delay after the flame is sensed during heatingcycles. After this time delay, the indoor blowermotor will be energized to run on heating speed. TheControl also provides an indoor “blower off” delay.The 50A50-571 I.F.C. delay to off is not adjustable,all other 50A50 and 50A51 controls have fieldadjustable delays to off. The off delay time is fieldselectable by adjusting Dip-Switches 2 and 3 onthe Control.

Dip-Switch Settings or Jumper Wire

White-Rodgers Integrated Furnace Controls – 50A50 & 50A51 Series

1 2 3

ON

OFF

Cooling Fan Off Delay (seconds)

Switch 1/Jumper ON = 0 (Factory Setting)

Switch 1 OFF/Jumper cut = 80

Heating Fan Off Delay (seconds)

Switch 2 Switch 3 Time Time1

ON OFF 90 60

OFF ON 120 140

ON ON 1502 1002

OFF OFF 210 180

1 I.F.C. Control 50A50-473-474 and 50A51-495/507 use theseharmonized delay times, 50A50-571 heating time delay is100 seconds.

2 Factory setting.

50A51-405 Control

50A50-571 Control

1 2 3

ON

OFF

9

LED Flash Rate

Normal Operation

• The LED will flash for 1 second at power-up

• the LED will flash “FAST”, 1/4 second “ON” and1/4 second “OFF”, during a call for heat

• The LED will flash “SLOW”, 1/4 second “ON” and3/4 seconds “OFF” with system in stand-by(power on).

Note: The LED will flash “ON” for approximately1/4 second, then “OFF” for approximately 1/4 second.The pause between groups of flashes is approximately2 seconds.

Fault Diagnostic

Continuous ON – Internal Fault, or groundedsensor (Lockout)

2 Flashes – System Lockout – No Flame1

3 Flashes – Pressure Switch Error

4 Flashes – Thermal ProtectionDevice Open

5 Flashes – Flame Sensing With Gas ValveDe-Energized(Stuck Open)

1 This fault will be caused if the hot leg and neutral leg ofthe 120 volt A.C. power legs are reversed.

White-Rodgers Self Diagnostic Features – 50A50/50A51 Series

The integrated furnace control incorporates systemfault analysis for quick gas flow shutoff, coupled withautomatic ignition retry upon sensing a fault correction.

The integrated furnace control tests for internaland external faults before allowing a heatingsequence to begin. The external check includes allsafety devices and pressure switches, makingcertain that they are in their proper normally openor normally closed position. If a fault is detectedby the control, it will immediately enter into afault mode and flash the LED light according tothe fault detected, see LED Flash Rate table at right.The control will remain in the fault mode until theproblem is corrected. Once the fault is cleared, thecontrol will start the heating sequence as long as thecall for heat still exists.

The control has an expanded diagnostic feature thatmonitors system performance. If a fault is detectedduring operation, the control will de-energize the gasvalve and flash the diagnostic LED according to thefault detected (see LED flash rate Table 3).

The control will automatically reset a lock-out dueto loss of flame. See I.F.C. Timing Table for reset time,see page 10.

Important:The control is mounted in the blower section.Do not remove blower door before checkingflash rate of LED. Sight glass is provided onupflow models in the blower door panel to preventresetting control and loss of diagnostics.

!

DiagnosticLED(Red)

10

White-Rodgers Integrated Furnace Control Timing

90, 1

20, 1

50, 1

80

90, 1

20, 1

50, 1

80

90, 1

20, 1

50, 1

80

90, 1

20, 1

50, 1

80

60, 1

00, 1

40, 1

80

60, 1

00, 1

40, 1

80

100

100

90, 1

20, 1

50, 1

80

60, 1

00, 1

40, 1

80

90, 1

20, 1

50, 1

80

90, 1

20, 1

50, 1

80

60, 1

00, 1

40, 1

80

60, 1

00, 1

40, 1

80

IFC

Tim

ings

50A5

0-40

5

50A5

0-40

6

50A5

0-47

1

50A5

0-47

2

50A5

0-47

3

50A5

0-47

4

50A5

0-57

12

50A5

5-57

10

50A5

1-40

5

50A5

1-49

5

50A5

1-50

5

50A5

1-50

6

50A5

1-50

7

50A6

1-62

5

1 St

age

IFC’

s

2 St

age

IFC’

s

E93

– E6

E93

– E6

E90

– E2

E90

– E2

E3 E3

E1 –

E2

E91

E93

– E3

E3 E90

E90

& 9

1

E90

E94

CNT1

309

CNT1

616

CNT1

848

CNT1

849

CNT2

182

CNT2

183

CNT2

181

CNT2

789

CNT1

308

CNT2

184

CNT1

523

CNT1

819

CNT2

223

CNT2

536

0 0 0 0 0 0 0 0 0 0 0 0 0 0

60 60 60 60 60 60 60 60 120

60 30 30 60 60

5 5 5 5 5 5 5 5 5 5 5 5 5 5

3 3 1 1 1 1 1 1 3 1 3 3 1 1

6 6 4 4 4 4 4 4 6 4 6 6 4 4

NA

8 30 30 30 30 30 30 NA

NA 0 30 30 30

45 45 45 45 45 45 45 45 45 45 45 45 45 45

0 0 0 0 2 2 2 0 0 2 0 0 0 0

0/80

0/80

0/80

0/80

0/80

0/80

0/80

0/80

0/80

0/80 7 7 7 7

2 2 2 2 2 2 2 2 2 2 2 2 2 2

4 4 4 4 10 10 10 10 4 10 4 4 10 10

120

120

120

120

60 60 60 60 120

60 120

120

60 60

17 17 17 17 17 17 17 17 17 17 17 17 17 20

27 27 1 1 1 1 1 1 27 1 27 27 1 9

17 17 11 11 11 11 11 11 17 11 17 17 11 11

27 27 21 21 21 21 21 21 27 21 27 27 21 21

5 5 5 6 5 5 5 5 5 5 5

X X X X X X X X X

X X

Part

I.D.

Safe

ty T

imes

(Sec

onds

)W

hite

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Mod

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vs.

Part

Num

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Circ

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Pre

Purg

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Purg

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IAP

3

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Igni

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IND

Off 4

Heat

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Auto

Res

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Cool

OnCo

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f No

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Retri

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Recy

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Rese

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Igni

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arm

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(Sec

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)Ac

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orie

s

Initi

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arm

-Up

Retry

War

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arm

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Max

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The

igni

tor s

tarts

with

a 1

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t-up

timin

g. A

fter 6

4 su

cces

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cyc

les,

the

timin

g w

ill b

e sh

orte

ned

each

cyc

le b

y 1

seco

nd u

ntil

11 s

econ

ds is

reac

hed.

If

a cy

cle

fails

to p

rove

flam

e, th

e tim

e w

ill in

crea

se b

y 2

seco

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to 1

3 se

cond

s, th

en to

15

and

so o

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21

seco

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11

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21

max

. If a

lock

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e co

unt s

tarts

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r.

50A5

0-57

1 IF

C us

es a

jum

per t

hat m

ust b

e cu

t to

obta

in C

ool O

ff De

lay.

Fac

tory

shi

pped

with

Jum

per n

ot c

ut =

No

Cool

Off

Dela

y.

IAP

= Ig

nitio

n Af

ter P

rovi

ng. (

The

amou

nt o

f tim

e th

at th

e ig

nito

r rem

ains

ene

rgize

d af

ter t

he M

ain

Burn

er F

lam

e is

sen

sed)

.

IND

Off =

Tim

e th

at th

e In

duce

r is

deen

ergi

zed

afte

r a fa

ult (

LED

3 Fl

ash)

to a

llow

con

dens

ate

wat

er (i

f any

) in

the

Hous

ing

to d

rain

.

Hum

idifi

er is

ene

rgize

d w

hen

the

Indu

cer a

nd th

e He

at S

peed

are

ene

rgize

d. (“

ON”

afte

r Hea

t On

Dela

y –

“OFF

” af

ter P

ost P

urge

).

Hum

idifi

er is

ene

rgize

d w

ith th

e In

duce

r Onl

y. (“

ON”

with

cal

l for

hea

t – “

OFF”

afte

r Pos

t Pur

ge.)

Tim

e de

lay

to O

FF i

s co

ntro

lled

by th

e IC

M-2

mot

or c

ontro

l boa

rd, D

IP s

witc

hes

num

ber 5

and

6.

Prio

r to

E-4

– N

/A, E

4 an

d la

ter i

s 30

sec

onds

.

Igni

tion

war

m u

p –

20 s

econ

ds, r

etry

20

seco

nds.

(Var

ies

volta

ge o

n ig

nito

r by

2% re

duct

ion

on s

ucce

ssfu

l cyc

les)

If cy

cle

fails

, the

n re

try, 6

% in

crea

se. I

f loc

kout

or p

ower

loss

, the

cou

nt s

tarts

ove

r.

1 2 3 4 5 6 7 8 9 07

Flas

hes

–8

Flas

hes

–Sl

ow F

lash

–Fa

st F

lash

–Co

ntin

uous

On

–

Gas

Valv

e Ci

rcui

t Err

or.

Low

Fla

me

Sens

e Si

gnal

.N

orm

al, N

o Ca

ll Fo

r Hea

t Pre

sent

.N

orm

al, C

all F

or H

eat P

rese

nt.

Inte

rnal

Con

trol F

ailu

re.

Diag

nost

ic In

dica

tor F

lash

Cod

es:

2 Fl

ashe

s –

Sys

tem

Loc

kout

(Ret

ries

or R

ecyc

les

Exce

eded

).3

Flas

hes

– P

ress

ure

Switc

h St

uck

Open

or C

lose

d.4

Flas

hes

– O

pen

High

Tem

pera

ture

Lim

it Sw

itch.

5 Fl

ashe

s –

Fla

me

Sens

ed W

ithou

t Gas

Val

ve.

6 Fl

ashe

s –

115

Vol

t AC

Pow

er R

ever

sed.

11

White-Rodgers 50A50/50A51 Fault Diagnostics

System Lockout (Loss Of Flame)When the Control fails to detect a flame currentsignal during the trial for ignition period,1 the gasvalve and ignitor will be de-energized and the retrysequence initiated. During the retry sequence, theinduced draft motor will be energized for an inter-purge period.1 The ignition sequence will be restartedwith an additional period1 of ignitor warm-up timefollowing the interpurge period. The Control willretry the ignition sequence 2 consecutive times(3 total) before system lockout.

When the Control has gone into system lockoutdue to loss of flame, the Control must reset beforethe system will restart the heating operation. TheControl may be manually reset by setting thethermostat system switch to OFF and then ONagain within 1 to 21 seconds or by interruptingsystem power to the Control for longer than 1 second.

The 50A50 and 50A51 Series Controls automaticallyreset a system lockout condition after one or twohours.1

Pressure Switch ProblemSingle-Stage Systems

When a call for heat is received and the pressureswitch contacts are sensed closed before the induceddraft motor is energized, the Control will delay energizingthe induced draft motor, stop the ignition sequenceand begin flashing the diagnostic LED 3 times to indicatea pressure switch problem. When the pressure switchcontacts open, a normal ignition sequence will begin afterthe contacts close again and the 3 flash fault will returnto steady fast flash to indicate a normal call for heat.

When a call for heat is received and the pressureswitch contacts are sensed open after the induceddraft motor is energized, the Control will not allow thegas valve to open. The ignition sequence will bestopped and the diagnostic LED begins flashing3 times to indicate a pressure switch problem. If thisoccurs, the problem may be induced draft motorfailure or excessive pressure against the blower outletand not allowing the pressure switch contacts toclose. When the pressure switch contacts close, a normalignition sequence will begin and the 3 flash fault willreturn to a steady fast flash to indicate a normal callfor heat.

If the control senses the pressure switch contacts areopen during a normal heating cycle, the gas valve willbe de-energized to remove the flame and the systemshutdown sequence initiated, induced draft motor willcontinue to run. This problem may also be due toinduced draft motor failure or high wind. The Controlwill begin flashing the diagnostic LED 3 times toindicate a pressure switch problem. When thepressure switch contacts close, a normal ignitionsequence will begin and the 3 flash fault will return toa steady fast flash to indicate a normal call for heat.

1 See Integrated Furnace Control Label or Timing Chart.

IMPORTANTIGNITION CONTROL IS POLARITY SENSITIVE.HOT LEG OF 120 VOLT POWER SUPPLYMUST BE CONNECTED TO THE BLACK LINEPOWER LEAD AS INDICATED ON WIRINGDIAGRAM OR IGNITION LOCKOUT WILL OCCUR.

The initial ignition sequence will be recycled, orrepeated, if the flame is sensed and then lost after10 seconds. The Control retry counter will be resetif the flame is sustained for longer than 10 secondsduring an ignition recycle attempt. The system willlockout if the flame is not sustained after the 4th or 10th1ignition recycle attempt.

A momentary loss of gas supply, flame blowout, or ashorted or open flame sensor will be sensedwithin 0.7 seconds during a normal heating cycle.The Control will then de-energize the gas valve andrecycle the ignition sequence. As long as the callfor heat still exists, a normal heating operationwill resume if the gas supply returns or the faultcondition is corrected before the 4th or 10th1 ignitionrecycle. Otherwise, the Control will go into system lockout.

When a system lockout occurs, the Control de-energizesthe gas valve, energizes the induced draft motor (lowspeed on 50A51 Controls) and energizes the indoor bloweron heat speed. The diagnostic LED will begin flashing 2times to indicate a system lockout due to loss of flame.

If a momentary (50 milliseconds, or longer) lossof system power occurs during a normal heatingcycle, the gas valve will be de-energized. When thepower is restored, the gas valve will remain de-energizedand the ignition sequence restarted as long as the callfor heat still exists.

12


50A50-405/406 Prior To Revision E4If the condensate drain is blocked on condensing(90%) furnace models, either by debris, improperdraining, or by freezing condensate, the pressureswitch contacts will open. When the Control sensesthe pressure switch contacts are open, the gas valvewill be de-energized to remove the flame and thesystem shutdown sequence initiated. The Control willbegin flashing the diagnostic LED 3 times to indicatea pressure switch problem. The system will remainshutdown until the condensate drain has been clearedand the condensate flows freely. When the pressureswitch contacts close, a normal ignition sequence willbegin and the 3 flash fault will return to a steady fastflash to indicate a normal call for heat.

During a normal heating cycle, if the 50A50-405/406Rev. E4-E6/471/472/473/474/571 Control senses thepressure switch contacts are closed and then open thegas valve will be de-energized to remove the flame, ifthe pressure switch does not reclose in 60 seconds theinduced draft motor will be de-energized for 30 seconds.After the 30 second delay, a normal ignition sequencewill begin. On condensing (90%) models, the delayallows any condensate, that may be blocking thepressure switch sensing tube, time to drain. On 80%models, the delay provides another attempt for theinduced draft motor to reach maximum speed andclose the pressure switch contacts.

Pressure Switch Problem50A51-405 Two Stage and 50A51-505 Two StageVariable-Speed Systems

On systems using 50A51-405 two-stage and 50A51-505two-stage variable-speed Controls, the first stagepressure switch fault diagnostic operation is the sameas the 50A50-405/-406 Controls. (Prior to Revision E4.)

During a normal 1st stage heating cycle, when thethermostat calls for 2nd stage heat, there will be a30 second delay between 1st and 2nd stage heat. Ifthe thermostat calls for 1st and 2nd stage heat at thesame time, there will be a 10 minute delay between1st and 2nd stage heat.

During the 1st stage ignition sequence, the induceddraft motor will always be energized to high speed. Whenthe Control senses the 1st stage pressure switch closed,the induced draft motor is energized to low speed.

If the 1st stage pressure switch closes and then opensduring the ignitor warm-up period, the Control willbegin flashing the diagnostic LED 3 times to indicatea pressure switch problem and wait 10 seconds forthe pressure switch contacts to close. If the 1st stagepressure switch contacts close, a normal ignitionsequence will resume and the 3 flash fault will returnto a steady fast flash to indicate a normal call for heat.

If the 1st stage pressure switch contacts do not close in10 seconds, the induced draft motor is energized to highspeed in an attempt to close the contacts. When thecontacts close, a normal ignition sequence willresume and the induced draft motor will remainenergized on high speed until the flame is sensed fora minimum of 10 seconds. The induced draft motorwill then be energized to low speed and the 3 flashfault will return to steady fast flash to indicate a normalcall for heat. If the 1st stage pressure switch contactsdo not remain closed and the ignition sequence hasbeen recycled for the 4th time, the Control will go intosystem lockout and begin flashing the diagnosticLED 2 times to indicate a system lockout due to lossof flame.

During a 2nd stage call for heat, if the 2nd stagepressure switch contacts do not close within the30 second delay between stages, the Control willde-energize the gas valve to remove the flame andbegin flashing the diagnostic LED 3 times to indicatea pressure switch problem. After the Control sensesthe loss of flame, a 3 minute error timer will bestarted and the shutdown sequence initiated as ifthe call for heat were removed. The induced draftmotor will remain energized on high speed for a5 second postpurge and the (selected) indoor blower“off” delay timer will begin.

After the 3 minute error time delay, the Control willrestart the heating cycle if the thermostat is stillcalling for 1st and 2nd stage heat. If the 2nd stagepressure switch contacts still have not closed after the10 minute delay between stages, the Control willrepeat the above shutdown sequence as long as thethermostat calls for 2nd stage heat.


13



Pressure Switch Problem50A51-495/-506/-507 Two Stage Variable-Speed Systems

The induced draft motor will always be energized tohigh speed. The induced draft motor will be energizedto low speed when the Control senses the 1st stagepressure switch contacts have closed.

If the 1st stage pressure switch contacts open duringa normal 1st stage heating cycle, the gas valve willbe de-energized to remove the flame and the induceddraft motor will be energized to high speed for10 minutes. If the 1st stage pressure switch contactsclose during the 10 minute high speed purge, theControl will restart the ignition sequence. If the1st stage pressure switch contacts remain closed after10 minutes, the induced draft motor will be energizedto low speed and a normal heating operation willcontinue. If the pressure switch contacts do not closeafter 10 minutes, the induced draft motor will beenergized again to high speed for 10 minutes and thediagnostic LED will begin flashing 3 times to indicatea pressure switch problem. Recycling the induceddraft motor will continue as long as a 1st stage callfor heat exists and the Control will not go into lockout.

The 2nd stage pressure switch fault diagnosticoperation is the same as 50A51-405/-505 Controls.

Thermal Protection DevicesAt any time during a call for heat, if the Control sensesthe high temperature limit (and/or aux. limit) or flameroll out switch(es) are open, the gas valve is de-energized,the induced draft motor is energized (low speed on50A51 Controls), and the indoor blower is energizedto run on heat speed.

On models utilizing fusible link devices, the fusiblelink is a single use device and must be replacedif it has opened. However, if the temperaturethe fusible link senses is approaching the triptemperature but does not exceed it, the contacts mayopen and close intermittently. The Control will initiateanother ignition sequence upon the closure of theintermittent fusible link.

Flame Sensed With Gas Valve OffAt any time the Control senses a flame current signalwithout a call for heat or when the gas valve isde-energized, the induced draft motor is energized(low speed on 50A51 Controls), and the indoor bloweris energized to run on heat speed.1 The Control willgo into system lockout and will not reset until thisfault is corrected. The diagnostic LED will beginflashing 5 times to indicate the flame sensed with thegas valve de-energized.

Slow Flash – Normal, No Call For Heat Present.

Fast Flash – Normal, Call For Heat Present.

Continuous On – Internal Control Failure.

Diagnostic Indicator Flash Codes:2 Flashes – System Lockout (Retries or Recycles Exceeded).

3 Flashes – Pressure Switch Stuck Open or Closed.

4 Flashes – Open High Temperature Limit Switch.

5 Flashes – Flame Sensed Without Gas Valve.

6 Flashes – 115 Volt AC Power Reversed.

7 Flashes – Gas Valve Circuit Error.

8 Flashes – Low Flame Sense Signal.

See Pages 14 and 15 for Sequence of Operation andWire Schematic.

1 Fuse only on 474 Model and Dip Switches replace jumpers.

CNT2789

White-Rodgers 50A55-571/-474 Self Diagnostic Features

PARK LINE-HPARKCOOL-H

HEAT-H XFMR-H

E17

E16 E18 E14

E28 E27 E13

LINE-N

XFMR-N

CIR-N

ONOFF

E4 E7

E8

E9

E10

E11K5K3K2

C4 E4

Y W R G C

E1

K6

FUSE1

1

DS1DS2

K1

1234

14

Single Stage 50A50 and 50A55 Sequence of Operation

White-Rodgers Integrated FurnaceControls 50A50-405/-406/-471/-472/-473/-474/-571 and 50A55-571/-474ModelsWhen the disconnect 1 is in the “ON” position, poweris applied through the blower door interlock switch 6to the control line voltage input terminal 8 and out ofthe control to the primary side of the control transformer“XFMR” 9. The low voltage side of the transformersupplies 24 volts to the control through terminals“TH” o and “TR” i. Control terminal “R” ; supplies 24volts to the “R” terminal of the room thermostat.

Once power is applied, the control flashes the LED“ON” for 1 second and performs a self check routine.Following the normal system check, the controlflashes the LED light once per second continuously(slow flash) while in stand-by.

On a call for heat, 24 volts is applied from the thermostatterminal “W” to the “W” terminal ; on the control. Thecontrol checks and confirms normally closed contacts atthe temperature cut out “TCO” f, the auxillary limit(downflow and some upflow/horizontal models), theflame roll-out fuse link (two fuse links are used ondownflow and upflow/horizontal models) f and jand normally open contacts of the safety pressureswitch “PS” f. With all safety and control switchesin their proper position, the control will energize theinduced draft motor y and flash the LED light two timesper second continuously (fast flash) during a call for heat.

When the safety pressure switch “PS” f closes, thecontrol begins the ignition sequence. The hot surfaceignitor y is energized for several seconds (see note)allowing the thermal element to heat up. The controlthen switches on 24 volts to the gas valve “MV” termi-

nals #1 a. The redundant and main solenoids areenergized allowing gas flow and main burner ignition.When flame current is detected by the control throughits terminal “FP” k, the 45 second indoor blower motordelay on timing begins. Flame failure response timeis set for 2 seconds. After flame has been establishedfor ten seconds, the flame failure response time isreset for 0.7 seconds. If flame current is not sensed by thecontrol k within the trial for ignition period (see note),the redundant and main gas valve solenoids a arede-energized. The control will begin a interpurgecycle and adds additional seconds to the hot surfaceignitor warm-up timing (see note). The controlenergizes the gas valve a for the second attempt toestablish main burner ignition. If flame current is notsensed by the control on the 2nd retry within the trialfor ignition period (see note), the control will repeat theprevious cycle one additional time before locking out.

At the end of the indoor blower delay on time, line voltageis applied at the controls terminal “HEAT” 5 energizingthe indoor blower motor at heating fan speed, supplyingwarm air to the space.

When the thermostat is satisfied, the gas valve’s redundantand main solenoids a are de-energized, extinguishingmain burner flame. Once the control senses loss offlame current (0.7 sec.) k, the induced draft motor t isde-energized after a five second post purge cycle. Theindoor blower motor delay off timing begins. At thecompletion of the fan delay off timing, the indoorblower motor 5 is de-energized and the cycleis complete.

Note: See Timing Chart for details or Integrated FurnaceControl Label.

15

Wiring Schematic

Note: See Integrated Furnace Control on Timing Chart for Control Details.

C

M2

1, 3

FLAMESENSOR

GR

GND

GAS VALVE

120 VOLT, 60 HZ., 1 PH.POWER SUPPLY

PER LOCAL CODES1

2

3

456789

q

werty

uiopasdfghjkl

;z

0

I.D.BLOWER

MTR.

N H

GR

GR

GR

24V

GND

BK

“A”

“B”

“C”

BK/1

BK/4

BK/3

BK/2

WH

WH/1

WH/4

OPTIONAL

COOL

HEAT

PARK

PARK

LINE

XFMR

EAC

HUM

CIR N

LINE N

XFMR N

EAC N

HUM N

6

3

9

12

4

5

10

7

11

1

2

8

TR

TH

MV

MV

PS

HLI

HLO

FP

GND

OR

YL

GND

GND

BKWH/

1

CF

BR BR

DOORSWITCH

GND

50A50-ALLINTEGRATED FURNACE CONTROL

HOT 120VACNEUTRAL

NEUTRAL 120VAC

DIPSWITCH

ON

DIAGNOSTICLED

OFF1 2 3

BK

WH

IGNITOR

FUSE LINK4YL/2

YL/3

YL/4

3

TCOYL/1

Y W G R C

TO THERMOSTAT

1

2

3

4

IND

IGN

IND N

IGN N

BK/6

BK/5

WH/6

WH/5

BL

RD

BL/1

RD/1

1 USED ON 90% FURNACE MODELS ONLY.2 DIRECT VENT MODELS HAVE ONE MANUAL

RESET FLAME ROLL OUT SWITCH INSTEADOF TWO, SINGLE-USE FUSIBLE LINKS.

3 USED ON DOWNFLOW/HORIZONTAL ANDUPFLOW/HORIZONTAL MODELS. TCO-B ISREVERSE FLOW SWITCH.

4 MAY BE A FUSE LINK OR BIMETAL SWITCH.

TCO-BYL/5

WH

PRESSURESWITCH

TNS

120V

IND.MTR.

TCO-B1BK BK

WH WH

JUMPER50A50-571

HOT 120VAC

FUSE LINK2 3 4

Single Stage (White-Rodger’s 50A50 and 50A55 Series Integrated Furnace Controls)

16

Two Stage 50A51 Sequence of Operation

White-Rodgers Integrated FurnaceControl 50A51-405/-495 ModelsWhen the service disconnect 1 is in the “ON” position,power is applied through the blower door interlockswitch 6 to the controls line voltage input terminals 8and out of the control to the primary side of thecontrol transformer “XFMR” u. The secondary sideof the control transformer supplies 24 volts to thecontrol through terminal “TH” and “TR” po. Controlterminal “R” ; supplies 24 volts to the “R” terminalof the room thermostat.

Once power is applied, the control flashes the LEDlight “ON” for one second and performs a self checkroutine. Following the normal system check, thecontrol flashes the LED one time per second (slow flash)continuously while in stand-by.

On a call for heat, 24 volts is applied from the roomthermostats “W1” terminal to the “W1” terminal zon the control. The control checks and confirmsnormally closed contacts at the temperature cut out“TCO” j, auxillary limit (downflow and someupflow/horizontal models), the flame roll-out fuse link(two fuse links are used on downflow and upflow/horizontal models) l and normally open contacts atthe safety pressure switch #1 j. With all safety andcontrol switches in their proper position, the controlwill energize the induced draft motor on high speed wand flashes the LED two times per second continuously(fast flash) during a call for heat.

When safety pressure switch “#1” j closes, thecontrol switches the induced draft motor to low speed wand begins the ignition sequence. The hot surface|ignitor w is energized for several seconds (see note)allowing the thermal element to heat up. The controlthen switches 24 volts to its “MVL” and “MV COM” gterminals to terminals #1 g and #2 f on the gasvalve. The redundant and main solenoids are energizedallowing gas flow and main burner ignition. Whenflame current is sensed by the control through its“FP” ; terminal, the 45 second indoor blower motortime delay “ON” begins. Flame failure response timeis set for 2 seconds. After flame has been establishedfor 10 seconds, the flame failure response time isreset for 0.7 seconds. If flamed current is not sensed bythe control within the trial for ignition period (see note),

the main valve low and redundant gas valvesolenoids g, a are de-energized. The control willbegin a interpurge cycle and adds additional secondsto the hot surface ignitor warm-up timing (see note).The control energizes the gas valve for the secondattempt to establish main burner ignition. If againflame current is not sensed by the control within thetrial for ignition period (see note), the control will repeatthe previous cycle before locking out. At the end ofthe indoor blower motor delay “ON” timing, linevoltage is applied at control terminal “HEAT LO” 6energizing the indoor blower motor at low heat fanspeed, supplying warm air to the space.

If the temperature in the space continues to fall, thethermostat second stage contacts “W2” close.24 volts is switched from thermostat terminal “W2” tothe “W2” terminal z on the control. A 30 second,2nd stage recognition time delay begins. At the end ofthe 30 second delay, the induced draft motor isswitched to high speed w causing pressure switch #2 dto close. When pressure switch #2 closes, 24 volts isswitched from control terminal “MVH” d to the gasvalve terminal #3 d energizing the second stagesolenoid allowing increased gas flow to the burners.At the same time, the indoor blower motor isswitched to high heat fan speed 7.

When second stage thermostat contacts “W2” satisfy,the induced draft motor is switched back to low speed wcausing pressure switch #2 d to open breaking thecircuit to the second stage gas valve solenoid d. Gasflow is reduced to the burners. The indoor blowermotor will switch back to low heat fan speed after a30 second delay 6.

When first stage thermostat contacts “W1” satisfy,the main valve low and the redundant gas valvesolenoids g are de-energized extinguishing mainburner flame. Once the control senses the loss offlame current (0.7 sec.) ;, the induced draft motor wis de-energized after a five second post-purge cycle.The indoor blower motor “OFF” timing begins. At theend of the indoor blower motor “OFF” timing, theindoor blower motor is de-energized and the cycleis complete.


17

Wiring Schematic

Two Stage Heat (White-Rodgers 50A51 Series Integrated Furnace Control)

GAS VALVE


PER LOCAL CODES1

2

3

456789

q

werty

uiopasdfghjkl;z

0

I.D.BLOWER

MTR.

N H

GR

GR

GR

24V

TNS

GRIND.MTR.

1

2

3

4

5

IGN

IND HI

IND LO

IND N

IGN NGND

BK/5

BK/6

RD/6

WH/6

WH/5

BK

“A”

“B”

“C”

BK/1

BK/4

BK/2

BK/3OPTIONAL

COOL

PARK

HEAT LO

HEAT HI

LINE

XFMR

EAC

HUM

WH/1

WH/4

WH

LINE N

XFMR N

CIR N

EAC N

HUM N

9

5

10

2

1

8

7

4

12

6

11

3

TR

TH

GND

PS2

MVH

MVCOM

MVL

GND

PSI

HLI

HLO

FP

BL

RD

BR

OR/1

BL/1

RD/1

OR

YL

YL/5

WH

GND

GND

BKWH/

1

CF

BR BR

DOORSWITCH

GND

50A51-405INTEGRATED FURNACE CONTROL

HOT 120VAC

NEUTRAL120VAC

DIPSWITCH

ON

DIAGNOSTICLED

OFF1 2 3

120V

WH

WH

IGNITOR

PRESSURE SWITCH2ND STAGE

BR/1HI

B/C

LO

3

2

1PRESSURE SWITCH

1ST STAGE

FLAMESENSOR

GND

FUSE LINK1 2

YL/2

YL/3

YL/4

1 TCO-B

TCOYL/1

1 USED ON DOWNFLOW/HORIZONTAL ANDUPFLOW/HORIZONTAL MODELS. TCO-B ISREVERSE FLOW SWITCH.

2 MAY BE A FUSE LINK OR BIMETAL SWITCH.

W1 W2 Y R G B COM

CL HI LO

TO THERMOSTATFURNACETWINNING

CONNECTOR

HOT120VACNEUTRAL

FUSE LINK 2

Note: See Integrated Furnace Control on Timing Chart for Control Details.

18

White-Rodgers Integrated FurnaceControls 50A51-505/-506/-507 and50A61-605 ModelsWhen the service disconnect 1 is in the “ON” position,power is applied through the blower door interlockswitch 3 to the controls line voltage input terminals 6and out of the control to the primary side of thecontrol transformer 9, and from the “CIRC” 7terminal to the ECMTM Fan Motor 3. The secondaryside of the control transformer supplies 24 volts to thecontrol through terminal “TH” and “TR” w, e. Controlterminal “R” g supplies 24 volts to the “R” terminalof the room thermostat.

Once power is applied, the control flashes the LEDlight “ON” for one second and performs a selfcheck routine. Following the normal system check, the control flashes the LED one time per second (slow flash)continuously while in stand-by.

On a call for heat, 24 volts is applied from the roomthermostats “W1” terminal to the “W1” terminal gon the control. The control checks and confirmsnormally closed contacts at the temperature cutout “TCO” a, auxillary limit (downflow and someupflow/horizontal models), the flame roll-out fuse link(two fuse links are used on downflow and someupflow/horizontal models) a and normally opencontacts at the safety pressure switch #1 p. With allsafety and control switches in their proper position,the control will energize the induced draft motor onhigh speed 9 and flashes the LED two times persecond continuously (fast flash) during a call for heat.

When safety pressure switch “#1” p closes, thecontrol switches the induced draft motor to lowspeed 0 and begins the ignition sequence. The hotsurface ignitor 9 is energized for several secondsallowing the thermal element to heat up. The controlthen switches 24 volts to its “MVL” i and “MVCOM” u terminals to terminals #1 i and #2 u onthe gas valve. The redundant and main solenoids areenergized allowing gas flow and main burner ignition.When flame current is sensed by the control throughits “FP” f terminal, the 45 second indoor blowermotor time delay “ON” begins. Flame failure responsetime is set for 2 seconds. After flame has beenestablished for 10 seconds, the flame failure responsetime is reset for 0.7 seconds. If flamed current is notsensed by the control f within the trial for ignitionperiod, the main valve low and redundant gas valvesolenoids i are de-energized. The control will begina 30 second interpurge cycle and adds additional

Two Stage Variable Speed Sequence of Operation

seconds (see note) to the hot surface ignitor warm-uptiming. The control energizes the gas valve for thesecond attempt to establish main burner ignition.If again flame current is not sensed by the controlwithin the trial for ignition period (see note), thecontrol will repeat the previous cycle before lockingout. At the end of the indoor blower motor delay“ON” timing, the microprocessor will close thenormally open K3 relay contacts j completing a24 volt signal circuit to pin #15 of the ECMTM motor,signaling it to turn on and run at the low heat blowerspeed, supplying warm air to the space. 24 voltsW1 g terminal from the thermostat is also appliedto the ECMTM motor harness pin #12h, which signalsthe ECMTM motor to run at the low heat speed setting.

If the temperature in the space continues to fall, thethermostat second stage contacts “W2” close.24 volts is switched from thermostat terminal “W2” tothe “W2” terminal g on the control. A 30 second,2nd stage recognition time delay begins. At the endof the 30 second delay, the induced draft motor isswitched to high speed 9 causing pressure switch#2 o to close. When pressure switch #2 closes,24 volts is switched from control terminal “MVH” o tothe gas valve terminal #3 o energizing the secondstage solenoid allowing increased gas flow to theburners. At the same time, the microprocessorcloses the normally open K1 relay contacts jcompleting a 24 volt signal circuit to pin #13 k of theECMTM2 motor signaling the indoor blower motor torun at the high heat blower speed.

When second stage thermostat contacts “W2” satisfy,the induced draft motor is switched back to lowspeed 0 causing pressure switch #2 y to openbreaking the circuit to the second stage gasvalve solenoid y. Gas flow is reduced to the burners.The indoor ECMTM blower motor 4 will be switchedback to the low heat fan speed after a 30 second delay.

When first stage thermostat contacts “W1” satisfy,the main valve low and the redundant gas valvesolenoids i are de-energized extinguishing mainburner flame. Once the control senses the loss offlame current (0.7 sec.)f, the induced draft motor 9is de-energized after a five second post-purge cycle.The indoor blower motor “OFF” timing begins. At theend of the indoor blower motor “OFF” timing, the indoorblower motor is de-energized and the cycle is complete.


19

Wiring Schematic

Two Stage Variable Speed (White-Rodgers 50A51 and 50A61 Series IntegratedFurnace Controls)

1

234

qw

u

0

GND

TO THERMOSTAT

1 LINE CHOKE NOT USED ON ALL MODELS.2 USED ON DOWNFLOW/HORIZONTAL AND UPFLOW/HORIZONTAL

MODELS. TCO-B IS REVERSE FLOW SWITCH.3 DIRECT VENT MODELS HAVE ONE MANUAL RESET FLAME ROLL

OUT SWITCH INSTEAD OF TWO, SINGLE-USE FUSIBLE LINKS, OR AUTO-RESET BIMETAL SWITCHES MAY BE USED ON SOME MODELS.

4 USE ON 90% FURNACE MODEL ONLY.5 MAY BE A FUSE LINK OR A BIMETAL SWITCH.


PER LOCAL CODES

N H

GR

GND

BKWH/

1

50A51-505/-506INTEGRATED FURNACE CONTROL

DIPSWITCH

DIAGNOSTICLED

2 3

DOORSWITCH

TNS

120V

GR

IND.MTR.

WH

WH

IGNITOR

GAS VALVE

PRESSURE SWITCH2ND STAGE

BR/13

2

1

FUSE LINK5

FLAMESENSOR

FUSE LINK2 3 5

YL/2

YL/3

YL/4

2 TCO-B

TCO

TCO-C4

YL/1

BK/2

BK/3OPTIONAL EAC

HUM

LINE

CIRCXFMR

LINE N

XFMR N

CIR N

TR

TH

GND

PS2

MVH

MVCOM

MVL

GND

PS1

HLI

HLO

FP

9

5

10

2

1

8

7

4

12

6

11

3

IGN

IND HI

IND LO

IND N

IGN N

PRESSURE SWITCH1ST STAGE

GND

GND

24V

HOT 120VAC

NEUTRAL120VAC

ECMTM2BLOWERMOTOR

LC1

5

4

3

2

1

JUMPERYL/BK

BK/8

WH/7

GR/BK

P2 ONOFF

R

W1

INW

2 IN

G IN

R OU

TG

OUT

N/C

W2

OUT

B OU

T

1 2 3 4 5 6 7 8

FANCFMECMTM FAN CONTROL

P1

DIP SWITCH

LVTB

BK O Y YLO G W1 W2 B

GR

16 WIRE HARNESS

1

GND

HI

B/C

LO

ONOFF

12345678

P2P2P2P2P2P2P2P2

W1 INW2 INGR OUTG OUTN.C.W2 CFM OUTB OUT

W1W2G

TERMINALBOARD

W1

G

W2

CFM

FAN

CFMON/OFF

P1

P1

P1

16 WIREHARNESS

INTEGRATED FURNACE CONTROLTYPICAL CONNECTION

COMPUTER

K3

K2

K1 TR

TH

R B/C24 VAC IN

INTERFACE CONTROL BOARDPIN CONNECTIONS

AT INTEGRATED CONTROL

2

15

13

8

1

h

jk

5

6

7

8

9

erty

iopasf

g

1

2

3

4

5

BR

OR/1

BL/1

RD/1

OR

YL

YL/5

WH

BK/1

BK/7

BK/4

WH/1

WH/4

WH/7

BL

RD

BK/5

BK/6

RD/6

WH/6

WH/5

20

Service TipsTo the qualified service man, these controls arevery simple and easy to work on. A list of requiredservice tools needed to work on any solid stateignition control today are listed below:

A reliable Volt/OHM Multimeter (preferably adigital with a microamp scale on it). The MicroampMeter is used to measure flame current.

A U-Tube Water Manometer (or pressure gauge) totest inlet and out gas valve pressure.

An Incline Manometer with a 0-2" water column scaleto test pressure switches and ductwork static pressure.

1. When the thermostat fan switch is placed in the“ON” position, the fan will run at heating fan speed.Low heat fan on two stage 50A51 series controls.

2. In order to obtain cooling air flow, the thermostat“Y” terminal must be connected to the “Y” terminalon the control. If the “Y” is not connected, lowheat speed will be activated during a cooling cycle.

3. If a single stage heat thermostat is used with the50A51 two stage control, there will be a 10 minutedelay between first and second stage heat if W1 andW2 are jumpered.

4. The control requires one microamp DC minimumflame current in order to maintain a call for heat.

5. The control will add seconds to the igniterheat-up period on second and third trial for ignitionwith interpurge between trials. See IntegratedFurnace Control label or Timing Chart for details.

6. Once flame current has been established by thecontrol for 10 seconds, the retry counter in the controlis reset to zero.

7. If flame current is interrupted, the control willbreak current flow to the gas valve and immediatelybegin a recycle for ignition without a purge cycle orincrease in igniter warm-up time. If flame current isinterrupted during 2nd stage operation, the recyclesequence is initiated and Hi fire or 2nd stage willresume immediately.

8. If a lockout occurs, the control automatically resetsthe trial for ignition sequence every one or two hoursprovided a call for heat continues to exist. See TimingChart , Reset Time Column, for details.

9. To reset control after lockout:

a. Interrupt line voltage power to the control fora minimum of 1 second.

b. Turn thermostat system switch off and back ontwice within 30 seconds.

10. Voltage input range:

Line 97-132 VAC 50/60HZ – Nominal 120 volts AC

Control 20-30 VAC 50/60HZ – Nominal 24 volts AC

11. 50A50 controls with date codes prior to 9348require an isolation relay in the “Y” circuitwhen used with Add On Heat Pump Plus One kits,to prevent cold air complaints during defrost.The control would not allow a cooling (Y) andheating (W) output at the same time so the controlwould de-energize the “W” circuit and there wouldbe no supplement heat during defrost cycles.

12. The humidifier accessory lead is energizedwhenever there is a heating call and the fan isoperating. See IFC Timing Chart for details, page10.

13. The electronic air cleaner accessory lead isenergized whenever there is a 24 volt signal on G or Yor during a heating call when the indoor fan isoperating.

A detailed troubleshooting chart for each model ofthe integrated furnace control is included in thismanual to help the service technician work throughabnormal conditions with these controls.

The troubleshooting section with fault charts for allWhite-Rodgers controls are located on pages 48through 62. See page 48 for procedures and chartreferences.

Integrated Control Quick Reference

21

Furnace ECMTM2 Motor Operation

A Call on “Y” and “G” together. The indoor blowerwill run at 100% and the red “Y” LED will be on,“YLO” LED if two speed outdoor unit.

“O” is the ramp, or time delay and humidistat enableinput. This “O” input must be received by the ECMTM2Motor Computer for these cycles to operate. Coolingonly units jumper “Y” to “O” at the low voltageMotor Control board.

Ramped Operation, Dip Switch No. 5 and No. 6 ON,will work in the cooling cycle only. A call on the “Y”,“G” and “O” together must be present for a rampedON and OFF cycle. If the “O” does not receive24 volts AC the 7 1/2 minute run period at 80% offull airflow will not occur.

Cooling Humidistat Operation – “BK” and “R”terminals are connected to the humidistat. When theindoor humidity is high, the humidistat’s switchwill be open and the blower air flow will be reduced20%. The red “BK” LED will be off when thehumidistat is open. If a humidistat for cooling is notused, “BK” terminal must be jumpered to “R”terminal. If not, only 80% of the cooling airflow willbe delivered. The red “BK” LED will be on whenthe humidistat is closed.

Air Flow Priority – is “W1” or “W2”, not thehighest airflow of “Y” or “W1” or “W2”. A Dual Fuelinstallation, a furnace and a heat pump, the airflowis compressor “Y” airflow except during the defrostcycle. Then the blower will run at W1 airflow whenthe furnace is on.

Cooling Cycle – Blower Time Delay to off iscontrolled by the ECMTM2 Motor and Dip SwitchNo. 5 and No. 6 on the Motor Control Board. TheWhite-Rodgers Ignition Control Dip Switch #1 mustbe set for 0 seconds turned on when a ramped ortime-delay cycle is selected.

Heat Exchanger Cool-Down Cycle – The airflowwill go to 50% of the cooling air flow. Heating cooldown time is controlled by the White Rodgers IgnitionControl, Dip Switches No. 2 and No. 3.

Fan Continuous Operation – The airflow is 50% ofthe cooling airflow. If cooling airflow is required forcontinuous operation, remove field installed wiresfrom “Y” terminal on the low voltage terminal boardand wire nut them together. Then connect “G” terminalto “Y” terminal with a jumper.

Green CFM LED – Will flash one time for each 100 CFMselected. Half flash for each 50 CFM selected.

DIP Switch Settings (ECMTM Fan Control)

1, 2 – Tonnage of Outdoor Unit

3, 4 – CFM Ton

5, 6 – Ramped/Enhanced

7, 8 – Heating Air Flow

DIP Switch Settings (Integrated Furnace Control)

1 – Always On

2, 3 – Heat Blower Off Delay, see IFC TimingChart for Details, page 10)

100% IF NECESSARY

50%

80%

50%

OFFOFF

1 Minute

DEHUMIDIFY

FAST COIL COOLING EFFICIENCY

7.5Minutes

3Minutes

COMPRESSOR OPERATION

FA

N O

PE

RA

TIO

N (

CF

M)

Cooling Only

Ramped Operation

22

Blower Motor Will Not Run1. Jumper 24 Volt A.C. “R” terminal to “G” terminal onthe Motor Control Board.

Does motor run?

No: Go to step number 2.

Yes: Motor runs, check thermostat and thermostatwire.

4. Is the line voltage to the motor high voltagepower plug pin 4 and pin 5 correct?

Furnace ECMTM2 motor correct voltage is 120 VoltsA.C. and there must be a jumper wire in this plugbetween pins 1 and 2.

No: Correct line voltage fault.

Yes: Line voltage correct and motor will not run.Replace motor.

2. Unplug 16 wire low voltage harness from themotor control board. Jumper 24 Volts A.C. to pins12, 15 and common pins 1 and 3.

Does the motor run?


Yes: Go to step number 5.

ECMTM2 Variable Speed Furnace Motor Quick Check

3. Unplug 16 wire low voltage harness from themotor. Jumper 24 Volts A.C. to motor low voltage plugpins number 12 and number 15 and pins number 1and number 3 which are common.

Note: Test plug can be made from a good harness tosimplify this check.

Does motor run?


Yes: Fault is in the 16 wire low voltage harness.Repair or replace it.

23

ECMTM2 Variable Speed Furnace Motor Quick Check

5. Plug the 16 wire low voltage harness from themotor back into the motor control board. Jumper“G IN” pin to “G OUT” pin of the White-RodgersIntegrated Control which plugs into the low voltagemotor control board.

Does the motor run?

Yes: Replace White-Rodgers Integrated Control.

No: Move the jumper to the metal partof the low voltage motor controlboard plug.

Does the motor run?

Yes: White-Rodgers Integrated Controlpins not making contact with motorcontrol board plugs. Clean pinsand plug by unplugging and plug-ging motor control board onto thepins of the integrated control orreplace both if necessary.

No: Repair or replace the motor controlboard.

GINW2W1

ROUT

GOUT

W2CFM

BOUT

NOT USED

JUMPER TO W/R PINS“G” IN & “G” OUT

GINW2W1

ROUT

GOUT

W2CFM

BOUT

NOT USED

JUMPER FROMSTEP # 1

24

Furnace Motor Control Board Schematic – CNT1537

PI 5PI 7PI 4PI 11PI 1PI 12PI 3PI 2PI 9PI 15PI 6PI 14PI 10PI 13PI 8PI 16

P2P2P2P2P2P2P2P2

D1

D2

D3

D4

D5

D6

D7

D8

1

2

3

4

5

6

7

8

BRW2W1OGYLOYBK

12345678

DIP SWITCHES

16 WIRECONNECTION

TO ECMTM

L1

L5

LED

L2 FAN

TERMINALBLOCK

LED N/C

D14 R3

R4 R1 R2C1

D9

FACTORY TEST PINS

TP1

TP2

TP3

TP5

FACTORY TEST PINS

TP6

TP4

TP7

CFMLED

L4

LEDL3

LED

SEEDIAGRAM

"A"

SEEDIAGRAM

"B"

P2P2P2P2P2P2P2P2

COMPUTER

TR

R B/C24 VAC IN

INTEGRATED FURNACE CONTROLTYPICAL CONNECTION

TH

12345678

DIAGRAM "B"

16 WIRECONNECTION TO ECMTM

DIAGRAM "A"

OD UNIT SIZEAIRFLOW ADJUSTOFF-DELAY OPTONSAUX HT. AIRFLOWCOMMONREFERENCECOMMONW1 CFMOG FAN ON/OFFYLO CFMY CFMBKW2 CFMCFM LIGHT -CFM LIGHT +

PI 5PI 7PI 4PI 11PI 1PI 12PI 3PI 2PI 9PI 15PI 6PI 14PI 10PI 13PI 8PI 16

W1 INW2 INGR OUTG OUTN.C.W2 CFM OUTB OUT

K2

K3 K1

8

1

25

Flame Rectification Principle – Measurement

The White-Rodgers 50A50 and 50A51 integratedcontrols use the flame rectification principle to provethat flame is present after the gas valve has beenenergized.

The flame rectification principle is based on the factthat a flame can conduct electrical current. When apositive charge is placed on the flame sensor and aflame is present to complete the circuit from theburner surface or ground, current will flow from theburner ground (zero potential) through the flameto the flame sensor which has a greater positive charge.

The ignition control will sense the current flow andallow the gas valve to remain open and the heatingcycle to continue. The flame current is monitored bythe ignition control and will shut down the gas valveif the minimum flame sense current is not present formore than 0.7 seconds.

The 50A50 and 50A51 White-Rodgers integratedfurnace controls require a minimum of 1.0 micro ampsDC to prove flame.

The flame current microamp signal must be checkedas part of regular maintenance and during normalservice checks in order to properly diagnose theignition system.

The flame current microamp signal can be measuredwith many of the new digital volt OHM meters.However, there are many digital meters which donot have microamp scales but can read DC volts.

The flame current is measured by removing theflame sensor wire at the flame sensor and connectingit to one of the meter leads. The other meter lead isconnected to the flame sensor.

A flame current adapter for digital volt meters, Pub.No. 34-4816-01, see next page, is available whichallows flame current microamps to be measured onthe DC volt scale. The adapter has two leads with amale and female quick connect for easy hook up tothe flame sensor.

There is also a flame current tester and simulator kit,Pub. No. 34-4817-01, that provides capability tomeasure flame current with a digital DC volt meterand the ability to simulate flame current, check foradequate ground and confirm gas valve operation.See next page for additional information.

Flame Current Adapter KitPub. No. 34-4816-01

26

To Be Used With The FollowingWhite-Rodgers Control Models:50E47-060, 50A50 and 50A51 series

May be used on other ignition modules that havea separate (remote) flame current sensor rod.

Note 1Remember – System lock out is normal if line voltage,115V.A.C., leads are not connected to the furnacemodule correctly. Hot leg to hot line and neutral lineto neutral terminal.

2 Flashes – System Locked Out – White-Rodgers ControlSeries number 50A50 or 50A51

To Measure Flame Current1. Unhook white wire from flame sensor probe.

2. Connect white wire removed in Step 1 to the whitelead on the tester.

3. Connect the black lead to the flame sensor probe.

4. Plug in a digital V.O.M. into the jacks on thetester. Set V.O.M. to the D.C. volt scale. Meter mustbe a minimum of 10 megohms resistance on theD.C. volt scale.

5. Repower furnace and put in a call for heat.

6. Read the V.O.M. Voltage read equals microamps,or 2 volts equals 2 microamps.

To Simulate Flame Current1. Hook up tester and meter as above.

2. White-Rodgers Control number 50E47-060Connect the green wire to “TR” terminal at theWhite-Rodgers Control. White-Rodgers Controlnumber 50A50 Series or number 50A51 Seriesconnect the green wire to the Burner Frame.

3. Connect the red wire to the gas valvehot lead, normally the red wire on currentfurnaces. Use a V.O.M. to determine whichlead is the hot lead, if in doubt.

4. Repower furnace and put in a call for heat.Push red button down on the tester untilthe light comes on. Release the button atthis time. If light will not come on, gas valve isnot receiving 24 VAC power, go to Step 5.

5. Does the furnace continue to heat?Yes/No

Yes

W.R. Module is OK, check:

No

Did light on tester come on? Yes/No

1. Flame sensor

2. Burner ground

3. Rusty burner

4. Burner not making goodelectrical connection.

5. Flame not burning onflame sensor rod.

No

1. Check connec-tion and voltageat gas valve.

2. Move greentester wire tomodule groundterminal. Thisapplies only tofurnaces using anumber 50A50 ornumber 50A51control. Thetester green leadshouldalready be con-nected to the“TR” terminal onfurnaces using anumber 50E47-060 control.

3. Retest furnace –if no 24 VAC atgas valve, checkwiring and trans-former.If wiring andtransformer areOK, replacemodule.

Yes

1. Check gas valve,gas flow and hotsurface ignitor iffurnace did notcome on.

2. Check white wirefrom flame currentsensor going tomodule.

3. Check burnerframe ground wire.Move green testerwire from burnerframe to moduleground terminaland retest furnace.If furnace nowwill stay on, faultis in the burnergrounding.

4. Remember notenumber 1.

5. If number 2, num-ber 3, and number4 above did notcorrect problem,replace module.

White-Rodgers Flame Current Tester/Simulator

BURNER FRAME50A50 OR 50A51

CONTROLS

TO GAS VALVEHOT LEAD

RED WHITE

BLACK

GR

EE

N

RED LED

DIGITAL VOLT METER

DC VOLTS+ –

WHITE SENSOR LEAD (FP)

50E47 HSI CONTROL-TR

FLAME SENSOR PROBE

Flame Current Adapterand SimulatorPub. No. 34-4817-01

SIDE VIEW

TESTERSWITCH

27

Combustion Air Pressure Switch Check – Measurement

If the measured static pressure reading does not meetthe switch specifications, the following items shouldbe checked:

1. Pressure switch hose/tubing for cracks or looseconnections.

2. Inducer wheel for corrosion or loose blades.

3. Inducer for tight bearings or loose inducer wheel.

4. Vent system design (oversized/undersized/longlateral runs)

5. High altitude switches required at 4,000 ft. or moreabove sea level.

6. Crack in heat exchanger.

7. Flue box gaskets leaking.

Note:The switch setting and the last three digits of thefactory drawing number are stamped on the switch.Example: “PO1”, – .50" WC.

The “PO1” and “PO2” must not be interpreted as “PS1”and “PS2” on two stage models.

The combustion air pressure switch proves operationof the induced draft motor and that adequate air isprovided to ensure complete combustion of the fuelbeing supplied to the burner.

The induced draft motor and vent system performancecan be checked by connecting an inclined manometerto the pressure switch hose and measuring theoperating static pressure.

The direct vent furnaces have differential pressureswitches and require two connections to the manometer.See figure below.

The measured static pressure reading should becompared to the pressure switch specifications. Ifthe measured static pressure meets or exceeds thespecifications and the switch contacts will not transferthe following items should be checked:

1. Switch out of calibration

2. Defective pressure switch

3. Moisture in pressure switch tubing

4. Condensate trap or drain restricted(90% furnaces)

5. Incorrect switch installed

28

Furnace Pressure Switch Settings

Closing Opening High Closing OpeningPressure Pressure Factory Replacement Altitude Pressure Pressure Factory Replacement

Models In W.C. In W.C. Number Number Kit In W.C. In W.C. Number Part

✽ UD-C-A, B, C, D/✽ DD-C, A, B –0.65 –0.5 ± .05 C340071P01 SWT 1255 BAYHALT220 –0.56 –0.41 ± 04 C340071P03 SWT 1579

✽ UD-C-H/✽ DD-C-C2 –0.65 –0.5 ± .05 C340773P01 SWT 1741 BAYHALT238 –0.56 –0.41 ± .04 C340773P03 SWT 1830

✽ UD-R-A, B/✽ DD-R-A, B HI –0.65 –0.5 ± .05 C340071P01 SWT 1255 BAYHALT215 HI –0.56 –0.41 ± .04 C340071P03 SWT 1579

LO –0.31 –0.17 ± .03 C340191P02 SWT 1373 3 LO –0.31 –0.14 ± .03 C340191P04 SWT 1580

✽ UD-R-H/✽ DD-R-C2 HI –0.65 –0.5 ± .05 C340773P01 SWT 1741 BAYHALT239 HI –0.56 –0.41 ± .04 C340773P03 SWT 1830

LO –0.31 –0.17 ± .03 C340789P02 SWT 1760 3 LO –0.31 –0.14 ± .03 C340789P04 N/A

✽ UE-A-A, B/✽ DE-A-A, B –0.65 –0.5 ± .05 C330610P01 SWT 1600 BAYHALT224 –0.56 –0.41 ± .04 C330610P03 N/A

✽ UE-A-H, K/✽ DE-A-C, K2 –0.65 –0.5 ± .05 C340773P01 SWT 1741 BAYHALT238 –0.56 –0.41 ± .04 C340773P03 SWT 1830

✽ UJ-A –0.65 –0.5 ± .05 C330610P01 SWT 1600 BAYHALT224 –0.56 –0.41 ± .04 C330610P03 N/A

FUA/FCA-A-A –0.65 –0.5 ± .05 C340071P01 SWT 1255 BAYHALT220 –0.56 –0.41 ± .04 C340071P03 SWT 1579

FUA/FCA-A-B, C –0.65 –0.5 ± .05 C330610P01 SWT 1600 BAYHALT224 –0.56 –0.41 ± .04 C330610P03 N/A

FUA/FCA-A-D, E –0.65 –0.5 ± .05 C340773P01 SWT 1741 BAYHALT238 –0.56 –0.41 ± .04 C340773P03 SWT 1830

✽ UC/✽ DC040C –1.55 –1.40 ± .04 C340450P04 SWT 1633 BAYHALT228 –1.27 –1.09 ± .04 C340450P08 N/A

✽ UC/✽ DC060C –1.27 –1.04 ± .04 C340450P01 SWT 1630 BAYHALT226 –1.02 –0.86 ± .04 C340450P06 N/A

✽ UC/✽ DC080, 120C –1.51 –1.39 ± .04 C340450P03 SWT 1632 BAYHALT225 –1.27 –1.04 ± .04 C340450P01 SWT 1630

✽ DC100C948 –1.64 –1.46 ± .04 C340450P02 SWT 1631 BAYHALT228 –1.27 –1.09 ± .04 C340450P08 N/A

✽ UC100C948 –1.55 –1.40 ± .04 C340450P04 SWT 1633 BAYHALT225 –1.27 –1.04 ± .04 C340450P01 SWT 1630

✽ UC100C960 –1.41 –1.23 ± .04 C340450P09 SWT 1776 BAYHALT240 –1.16 –1.00 ± .04 C340450P10 N/A

✽ UX/✽ DX040C, ✽ UX100C9601 –1.44 –1.29 ± .04 C340545P01 SWT 1669 BAYHALT230 –1.21 –1.06 ± .04 C340545P05 N/A

✽ UX060C1 –1.09 –0.94 ± .04 C340545P02 SWT 1670 BAYHALT231 –0.92 –0.77 ± .04 C340545P06 N/A

✽ DX060C1 –1.13 –0.98 ± .04 C340545P12 SWT 1838 BAYHALT241 –0.97 –0.82 ± .04 C340545P13 N/A

✽ UX080C9421 –1.30 –1.15 ± .04 C340545P03 SWT 1671 BAYHALT232 –1.09 –0.94 ± .04 C340545P02 SWT 1670

✽ UX100C9481 –1.55 –1.40 ± .04 C340545P04 SWT 1672 BAYHALT233 –1.30 –1.15 ± .04 C340545P03 SWT 1671✽ UX/✽ DX120C9601

✽ DX080C9421 –1.52 –1.37 ± .04 C340545P09 SWT 1702 BAYHALT233 –1.30 –1.15 ± .04 C340545P03 SWT 1671

✽ DX100C9481 –1.55 –1.40 ± .04 C340545P04 SWT 1672 BAYHALT234 –1.44 –1.29 ± .04 C340545P01 SWT 1669

✽ UY/✽ DY060, 080H1 LO –1.09 –0.94 ± .04 C340545P02 SWT 1670 BAYHALT235 LO –0.92 –0.77 ± .04 C340545P06 SWT 1862✽ DY120R1

HI –1.76 –1.59 ± .05 C340545P08 SWT 1699 3 HI –1.44 –1.29 ± .04 C340545P01 SWT 1669

✽ UY100R1 LO –1.30 –1.15 ± .04 C340545P03 SWT 1671 BAYHALT236 LO –1.09 –0.94 ± .04 C340545P02 SWT 1670

HI –1.76 –1.59 ± .05 C340545P08 SWT 1699 3 HI –1.44 –1.25 ± .04 C340545P01 SWT 1698

✽ DY100R1 LO –1.30 –1.15 ± .04 C340545P03 SWT 1671 BAYHALT237 LO –0.92 –0.77 ± .04 C340545P26 N/A

HI –1.94 –1.75 ± .06 C340545P11 SWT 1710 3 HI –1.63 –1.44 ± .04 C340545P27 N/A

✽ UY120R1 LO –1.09 –0.94 ± .04 C340545P02 SWT 1670 BAYHALT242 LO –0.92 –0.77 ± .04 C340545P06 SWT 1862

HI –1.63 –1.48 ± .04 C340545P07 SWT 1698 3 HI –1.30 –1.15 ± .04 C340545P03 SWT 1671

1 The pressure switches for the ✽ UX/✽ DX/✽ UY/✽ DY furnaces are differential switches.2 The mounting method for 80+ furnace pressure switches changed with the introduction of the upflow/horizontal models in the 1st quarter of 1996.

Those changes are reflected in this table.3 These kits contain both pressure switches.Note: Switches listed on this page by model number are the latest switch listed as of 3/18/98 and may not have the same set point as the original factory installed switch.

Check T.S.B for the latest changes.✽ Models may be an A or T or F.

29

Gas Valves

Recommended Replacement

ProductionFurnace Model Gas Valve Natural Propane/LP

FUA/FCA-A-A A B B

FUA/FCA-A-B,C E E E

✽ UC-C-A,B/✽ DC-C-A,B,C A,B1 B B

✽ UD-C-A,B,H/✽ DD-C-A,B,C,D,J,K A,B1 B B

✽ UD/✽ DD-R-A C C,G,K,L2 D,G,K,L2

✽ UE/✽ DE-A-A,B E E E

✽ UJ-A-A E E E

✽ UX/✽ DX-C-A F F F

✽ UY/✽ DY-R-A G2 G2 G2

FUA-A-E/FCA-A-E H H HTUE-A-K/TDE-A-K

✽ UX/✽ DX-C-C I I I

✽ UC-C/✽ DC-C-C J J J✽ UD-C-H/✽ DD-C-C3

✽ UD-R-K/✽ DD-R-F L2 L2 L2

✽ UX-R-V, W/✽ DX-R-V, W L2 L2 L2

✽ UY-R-V, W/✽ DY-R-V, W L2 L2 L2

✽ UE-A-L/✽ DE-A-M M M M

✽ UX/✽ DX-C-C, D4 N N N

✽ UD-C-K/✽ DD-C-F4 O O O

✽ UE-A-L/✽ DE-A-M4 N N N

✽ UC-C-B/✽ DC-C-B4 O O O

✽ Models may be an A or T or F.1 Factory change from fast to slow opening valve in January, 1994.2 “G,” “K” or “L” valves approved for natural or propane.3 Factory Change, April, 1996 (L19 Datecode).4 Factory Change, August, 2001.

continued

30

Replacement Part No.

Opening Factory Outlet Propane Gas LP NaturalValve Models Supplier Characteristics Pressure Setting

40” residential gas furnace operation › furnace info › 40in gas furnace operation...

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