Bradford White U2TW75T*RN User manual

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Manual 238-50629-00A
SERVICE
MANUAL
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualified service providers)
Models Covered
by This Manual:
U2TW75T*RN
UTW475S76R*N
(*) Denotes Warranty Years
Gas Water Heaters
U TTW 75 Series
®

Bradford White
U2TW Series
Gas Water Heaters
Table of Contents
Page U2TW Service Procedure
Introduction 4 - - -
How to Use This Manual 5 - - -
Tool Required for Service 5 - - -
Specifications 6 - - -
Control Timings 8 - - -
Sequence of Operation 9 - - -
Troubleshooting 12 - - -
Burner and Inner Door/Gasket Removal, Inspection
Replacement and Reinstallation 14 I
Burner Operation Inspection, Cleaning and Replacement 17 II
Pilot Testing, Cleaning and Replacement 19 III
Pressure Switch Testing and Replacement 20 IV
Blower Testing and Replacement 22 V
Blower Temperature Switch Testing and Replacement 24 VI
Gas Control Testing and Replacement 26 VII
Simulated Resistive Device Testing and Replacement 28 VIII
Resettable Thermal Switch Testing and Replacement 29 IX
Safety Circuit Voltage Trace 31 X
115VAC Circuit Trace 32 XI
Dip Tube Inspection and Replacement 33 XII
Anode Inspection and Replacement 34 XIII
Flue Baffle Inspection and Replacement 35 XIV
Glossary of Terms 36 - - -
Parts List 39 - - -
Page 2
2

WARNING: If the information in these instructions is
not followed exactly, a fire or explosion may result
causing property damage, personal injury, or death.
WHAT TO DO IF YOU SMELL GAS
Do not try to light any appliance.
x Do not touch any electrical switch; do not use any
phone in your building.
x Immediately call your gas supplier from a neighbor's phone.
Follow the gas supplier's instructions.
x If you cannot reach your gas supplier, call the fire
department.
Installation and service must be performed by a qualified
installer, service agency or the gas supplier.
FOR YOUR SAFETY
Do not store or use gasoline or other flammable,
combustible, or corrosive vapors and liquids in the
vicinity of this or any other appliance.
CAUTION
Incorrect operation of this appliance may
create a hazard to life and property and
will nullify the warranty.
DANGER
Do not store or use gasoline or other
flammable, combustible, or corrosive
vapors and liquids in the vicinity of this
or any other appliance.
IMPORTANT
Beforeproceeding, please inspectthe
water heater and its components for
possible damage. DO NOT install any
water heater with damaged components.
Ifdamage isevident then please contact
thesupplier wherethewater heater was
purchased or themanufacturer listed on
therating plate for replacement parts.
WARNING
Water heatersareheat producing appliances. To avoid
damage or injury, donot storematerials against the
water heater or vent-air intakesystem. Use proper care
to avoid unnecessary contact(especially by children) with
thewater heater and vent-air intakecomponents.
UNDER NO CIRCUMSTANCES MUST FLAMMABLE
MATERIALS, SUCH AS GASOLINE OR PAINT THINNER BE
USED OR STORED IN THE VICINITY OF THIS WATER
HEATER, VENT-AIR INTAKE SYSTEM OR IN ANY
LOCATION FROM WHICH FUMES COULD REACH THE
WATER HEATER OR VENT-AIR INTAKE SYSTEM.
WARNING
DO NOT ATTEMPT TO LIGHT ANY GAS APPLIANCE IF YOU
ARE NOT CERTAIN OF THE FOLLOWING:
x Liquefied petroleum gases/propane gas and natural gas
have an odorant added by the gas supplier that aids in
the detection of the gas.
x Most people recognize this odor as a “sulfur” or “rotten
egg” smell.
x Other conditions, such as “odorant fade” can cause the
odorant to diminish in intensity, or ”fade”, and not be
as readily detectable.
x If you have a diminished sense of smell, or are in any
way unsure of the presence of gas, immediately contact
your gas supplier from a neighbor's telephone.
Gas detectors are available. Contact your gas supplier, or
plumbing professional, for more information.
CAUTION
Ifsweat fittings areto be used DO NOT apply heat to the
nipples on top of thewater heater. Sweat thetubing to
theadapter beforefitting theadapter to thewater
connections. Itisimperativethat heat isnot applied to
thenipples containing aplastic liner. WARNING
FAILURE TO INSTALL AND MAINTAIN A NEW, LISTED 3/4” X
3/4” TEMPERATURE AND PRESSURE RELIEF VALVE WILL
RELEASE THE MANUFACTURER FROM ANY CLAIM THAT
MIGHT RESULT FROM EXCESSIVE TEMPERATURE AND
PRESSURES.
WARNING
Hydrogen gas can be produced inan operating water
heater that has not had water drawnfrom thetank for a
long period of time(generally twoweeksor more).
Hydrogen gas isextremely flammable. To prevent the
possibility of injury under these conditions, we
recommend thehot water faucet to be open for several
minutes at thekitchen sink beforeyou use any electrical
appliancewhich isconnected to thehot water system. If
hydrogen ispresent, therewill be an unusual sound such
as air escaping through thepipes as hot water begins to
flow. Donot smokeor haveopen flamenear thefaucet
at thetimeitisopen.
CAUTION
Turnoff or disconnecttheelectrical power supply to the
water heater beforeservicing. Label all wires prior to
disconnection when servicing controls. Wiring errorscan
cause improper and dangerousoperation. Verify proper
operation after servicing.
Page 3
3

Page4
Introduction
ThenewBradfordWhite U2TW &UTW4water heaters are designedtoprovidereliable
performancewithenhancedstandardfeatures.Newdesign features includereliablesparkto
pilotignition system, enhanceddiagnostics,simplifiedservicing, significantly quiet operation
and additionalventlengths.Inaddition, the U2TW &UTW4water heaters provideUltra Low
NOx emissions.
SparktoPilot Ignition System-employing thesparkto pilotignition systempromotes
reliableand consistentpilotand main burner ignitionstoprovidehotwater on demand.
Integrated Immersion Thermostat/GasControl Valvewith LED -was developedfor ease
of troubleshooting by providing simplediagnostic codes to pinpointaninstallation or
componentperformanceissue.
Powerful Blower -will eliminate problemswith difficultventing situations.
Quieter and Cooler Blower Operation - blower noise issignificantly reducedforboth
interiorand exteriorenvironments. Cooler operation increases blower lifeby reducing bearing
wear and noise.
RuggedWiring Connections-receptacletypeconnectionspromote errorfree wiring.
IncreasedVent Lengths-increasedventing performanceisachieved whilemaintaining
Energy Factor&FHSR performance.
The U2TW &UTW4w
ater heaters useacombustion systemwhere fluegases are combined
with dilution airtoreducethefluegas temperature in theblower.Thediluted fluegases are
evacuatedtotheexteriorthrough low temperature ventmaterials.Thegas control maintains
water temperature, ignition sequenceand regulates gas flow. A safetycircuitconsisting of a
pressure switch and blower temperature switch verifies proper conditionsexist forsafeand
reliableoperation. If asituation outsideof normaloperating parameters exists,thegas control
diagnostic LED will flashacodetopositively identify anoperationalissue.
This servicemanualisdesignedtofacilitate problemdiagnosisand enhance serviceefficiency.
Please readthe servicemanual completely before attempting serviceon thisnewseries of
power ventmodels.
4

Tools Required for Service
It is intended for this manual to be used by qualified service personnel for the primary purpose of
troubleshooting and repair of the Bradford White U2TW Series water heaters. Understanding the
sequence of operation section of this manual will contribute greatly to troubleshooting the water
heater.
The Honeywell WV4462A Electronic Gas Control will display error codes in the event of abnormal
operation. Error codes are listed in the troubleshooting chart beginning on page 12 of this service
manual. The troubleshooting chart will also indicate the probable cause for the error code and
direct the service professional to a service procedure to properly diagnose the abnormal operation.
In some difficult to diagnose conditions, it may be necessary to isolate the heater from the vent
system to determine the problem.
Contact the Bradford White technical support group immediately if diagnosis cannot be made
using the methods described in this service manual.
Page5
Manometer:Aliquid “U” tube type or adigital type can be used. This device is used to
measure gas and/or air pressure and vacuum.
Multi-Meter:Adigital type is strongly recommended. This device is used to measure
electrical values. The meter you select must have the capability to
measure volts AC, volts DC, Amps, micro-amps and ohms.
Electronic Probes:In some cases, standard multi-meter probes will damageor simply
not be effective to obtain certain voltageand ohm reading.It will be
necessary to have special electronic “pin” type multi-meter probes.
These probes are available at most electronic wholesale outlets.
Thermometer:Used to measure water temperature. Anaccurate thermometer is
recommended.
Water Pressure Gauge:Used to measure water supply pressure. Also used to determine tank
pressure by adapting to the drain valve of the heater.
Various Hand Tools:Pipe wrench, channel locks, open end wrenchs (3/8",7/16",½"),
12" crescent wrench, Allen wrench set, screw drivers (common &
Phillips), ¼" nut driver, pliers (common & needle nose), socket set, side
cutters wire cutters, wire strippers, wire crimpers, torpedo level, small
shop vac, step ladder, flashlight and 5 gallon pail.
How to Use This Manual
5

Specifications
Thermal well ECO LimitResidential 188°F (87°C), Commercial 199°F (93°C)
Residential Temperature
SetPoint Range60°F (16°C) to160°F (71°C) (Approximatetemperatures)
Blower TemperatureSwitch Normally closed, opens@ 165°F (74°C), autoreset@ 130°F (54°C).
BlowerU2TW75 and UTW475SModels:
115VAC, 60Hz,3.1 amps, 3000 RPM,68C[email protected]" W.C.
Pressureswitch U2TW75 and UTW475SModels:
Normally open, closes on vacuum increase @-1.28, opens on vacuum decrease @-1.25
Power supply Dedicated 115VAC, 60 Hz, 15A
Approved Gas TypeNatural.
VentingSystemPower vent through thewall or vertical through theroof
Approved Vent Materials PVC, CPVCor ABS
Gas Supply PipeMinimum 1/2"NPT(schedule 40 black ironpiperecommended)
Minimum Clearance
for Servicing18" from top, 24" from front, 4" sides and rear.
Water Supply Pressure150 PSI maximum allowable workingpressure. Check local codes for supply pressure
Gas Pressure 6.0"W.C. min. and 14.0"W.C. max.
Commercial Temperature
SetPoint Range80°F (27°C)to 180°F (82°C)(Approximate temperatures)
Page6
6

Specifications
Venting Specifications:
Through the Wall
Terminating # of
Elbows
Maximum
Length ft (m)
Minimum
Length ft (m)
3" Diameter (7.6 cm) PVC Vent Connector Lengths
145(13.7) 2(.6)
Through the Wall 2 40(12.2)2(.6)
Through the Wall 3 35 (10.7)2(.6)
Through the Wall 4 30 (9.1)2(.6)
Through the Wall
Terminating # of
Elbows
Maximum
Length ft (m)
Minimum
Length ft (m)
4" Diameter (10.2 cm) PVC Vent Connector Lengths
1 175(53.3) 10(3.1)
Through the Wall 2 170(51.8)10(3.1)
Through the Wall 3 165(50.3) 10(3.1)
Through the Wall 4 160(48.8)10(3.1)
Through the Roof 0 50 (15.2) 7 (2.1)
Through the Roof 145(13.7) 7 (2.1)
Through the Roof 2 40(12.2)7(2.1)
Through the Roof 3 35 (10.7) 7(2.1)
Through the Roof 0 180(54.9) 15(4.6)
Through the Roof 1175 (53.3) 15(4.6)
Through the Roof 2 170 (51.8) 15(4.6)
Through the Roof 3 165 (50.3) 15(4.6)
Through the Wall 5 155 (47.2) 10(3.1)
Through the Roof 4 160(48.8) 15(4.6)
Vent Tables
Page 7
7

Control Timings
Ignition State Timing
Pre-purge2Seconds
Trial for Ignition90 Seconds
FlameStabilizationPeriod3Seconds
Inter-purge15Seconds
FlameFailureResponse Time1.5Seconds(2second. Maximum; 1second minimum.)
Post-purge15Seconds
PS FaultDelay (failed open/close)Retry after 2Minutes
Soft LockoutRetry after 5Minutes
ECO LimitLockoutIndefinite(cycle power torestart)
Simulated ResistiveLoad LockoutIndefinite(cycle power torestart)
HardwareError LockoutIndefinite(selfclearsiffaultclearsfor atleast15seconds)
Verify ResistiveDelayRetry after 2Minutes (repeats5times)
Specifications
Page8
WiringDiagram
8

Sequence of Operation
Thermostat Calls for Heat.
Prior to energizing blower,gas control checks safetycircuittoinsure the circuitisopen. Normal switchpositions
in the safetycircuit are as follows:
a) Pressure switchnormallyopen.
b)Blower temperature switchnormallyclosed.
If the safetycircuitisclosed, the control waits 4 seconds,gas control LED flashes 2 times with 3 second pause.
Gas control waits 2minutes then, blower runs for 30 seconds. Thiscycle repeats until safetycircuitopens.
Power up Sequence
1Start Up.
Uponpower up, the control runs a safe-start checkwithatypical start-up delayof 1-5 seconds.
2SimulatedResistive LoadDevice Check.
To assure no outputs are energized if the “Simulated Resistive device” is out of range,the control will test the
the device for proper operating range. If the deviceiswithin range the control resumes normal operationwith no
perceivable delay. If the deviceisoutofrange,the control LEDimmediatelyflashes 7 times with 3 second pause.
Normal Heating Sequence
1
2Blower Energizes.
3
Pressure Switch Proves Blower/VentSystem Operation.
If the pressure switchdoes not close within 30 seconds,the control LED Flashes 3 times with 3 second pause.
The blower runs for 30 seconds every2minutes trying to get the pressure switchorblower temperature switchto
close. Thiscycle repeats as long as there isacall for heat.
4
Blower Pre-purge Period(2seconds)
5Trial for Pilot Ignition(90 seconds).
a) The gas control lights the pilot by activating spark igniter and gas flowto pilot burner.
b) If flame isnot sensedwithin 90 seconds, igniter and gas floware deactivated, blower will post purgeand
control LED flashes 6 times with 3 second pause.
6Main Burner Ignition
After pilot flame issensed, gas control activates main valve for main burner ignition. The gas control will ignore
flame and pressure switchsignals for 3 seconds allowing for main burner to stabilize.
Page9
9

Steady State Operation.
DuringSteady State Operation theControl Monitors:
Thermostat temperature sensor-When set point temperature issatisfied,gasvalveis shutdown and
blower will postpurgefor 15seconds.Control LEDflashesashort flash onceevery 4 seconds(idle) status
code.
Pressure switch /Blower temperature switch-Ifeither switch opens, pilot valve and main valveis shut
down. Theblower continuesto runsfor 30 secondsattemptingto closethecircuit. Thecontrol LED Flashes
3 times with3second pause.
Flame Sensor-Ifflameislost,pilot & main valve are shutdown,blower runsfor 15seconds.Control attempts
to re-light pilot 4 times.Ifunsuccessful,Blower is shutdown and control proceedsto5minute lockout. Control
re-attemptsto light pilot startingat normal heatingsequence#2.
Thermostat Satisfies.
Burner Off.
Blower PostPurge(15seconds).
9
8
10
7
Sequence ofOperation
Abnormal Operation
1.Simulated ResistiveDeviceFault:
a)Ifthe resistance is greater than 70,000 Ohms-thegascontrol immediately turnsoff all outputs.Control waits
and monitorsresistancefor 30 seconds.Iftheresistanceisgreater than 70,000 ohms after 30 seconds, the
gascontrol proceedsto verifyresistive delay for 2minutesand flashes8 times then once withathree second
pause. Thisprocess isrepeated 5 timesuntil thecontrol either returnsto normal operation or proceedsto flashing
7 times witha3second pause.
b) If the resistance is below 3000 ohms-Thegascontrol immediately turnsoff all outputsand proceedsto flash
8 times then once withthree second pause. The error selfclearsiftheresistance returnsto normal rangefor at
least15seconds.
Normal HeatingSequence(cont.)
2.Temperature Sensor Fault:
a)Temperature sensor detectedopen circuit -Thegascontrol Immediately turnsoff all outputsand proceedsto
flash 8 times then twice withthree second pause. The error selfclearsifthefault clearsfor at least15seconds.
b) Temperature sensors not readingthe sametemperature within ±5.5 °F - Thegascontrol Immediately turnsoff
all outputsand proceedsto flash 8 times then three times withthree second pause. The error selfclearsifthefault
clearsfor at least15seconds.
c) Water temperature in excess of ECO (Energy Cut Out)limit -Thegascontrol immediately turnsoff pilot &
main valve and proceedsto flash 4 times with3second pause. Blower continuesto rununtil gascontrol isreset.
Theset point knobshould beturned to theminimum temperature settingfor at least6secondsand then turned
clockwiseby at least45
o.
Page10
10

Sequence of Operation
AbnormalOperation (cont.)
3.Pressure Switch/Blower Temperature Fault:
a) Pressure switchclosed at start of call for heat - Thegascontrolwaitsfoursecondsthen, proceedsto flash
2 times with3second pause.The controlwaits2 minutesand then turnson blower for 30seconds. Theblower
turnsoff after 30secondsand the controlwaitsfor pressure switchto open.Any time the Pressure switchopens,
theblower turnson (or stayson) and the controlproceedsto wait for pressure switchto close.
b) Pressure switchor blower temperature switchfailed open - Thegascontrolrunstheblower for 30seconds
waiting for the pressure switchand/or blower temperature switchto close.If either switchdoesnot closein30
seconds,theblower turnsoff and the controlflashes3 times with3second pause.Thegascontrolwaitstwo
minutesbefore turning on theblower for another 30secondsto see the circuit close.Thiscycle repeatsaslong as
there isacall for heat or untilthe circuit closes.
c) Pressure switchor blower temperature switchopensduring burner operation - Thegascontrolturnsoff the
pilot and main valve, runsblower for 15seconds(inter-purge) waiting for pressure switchand/or blower
temperature switchto close.If either switchfails to close, the controlproceedsasdescribed in 3b above.Ifthe
circuit closesagain by the end of the inter-purge, the recyclecounter isincremented, if the recyclecount has
not reached itslimit (4), another trialfor ignition begins. Ifthe recyclecount hasbeen reached, thegascontrol
turnsoff theblower and flashes6 times then 2 times with3second pause.Thegascontrolwaits5minutesbefore
repeating ignition sequence.
4. TrialFor Ignition Fault:
a) Pressure switchopensduring trial - Thegascontrolturnsoff igniter and pilot valve.Thegascontrolproceeds
asdescribed in 3b above.Ifthe pressure switchcloseswithin 30secondsthegascontrolwill continuewithtrialfor
ignition starting at blower pre-purge.
b) Flame Not Sensed - Thegascontrolenergizesthesparkigniter attempting to lightthepilot and prove flame.If
flame isnot sensed within 90seconds,the igniter turnsoff, thepilot valve isclosed and thegascontrolrunsthe
blower throughpostpurge and flashes6 times then once with3second pause.The controlwaits5minutesbefore
repeating the ignition sequence.
5. Flame Sensing Fault:
b) Flame lost during run - Thegascontrolturnsoff pilot and main valves,runsblower for 15seconds(inter purge).
Thegascontrolincrementsthe recyclecount, if the recyclecount hasnot reached itslimit (4), another trialfor
ignition begins. Ifthe recyclecount hasbeen reached, thegascontrolturnsoff theblower and flashes6 times
then 3 times with3second pause.Thegascontrolwaits5minutesbefore repeating the ignition sequence.
c) Flame sensed out of sequence - thegascontrolonlylooks for pilot flame when theblower isrunning.Ifflame is
present when thepilot valve isnot open, thegascontrolproceedsto wait for flame loss and flashes5 times with3
second pause.Thiscontinuesuntilflame islost, once theflame signalislost, the controlflashes6 times then 4
times with3second pause.The controlwaits5minutesbefore repeating the ignition sequence.
Page11
11

Shortflash, onceevery
four seconds
“Heartbeat”, alternates
bright/dim
Thermostatcalling
for heat(nofault).
Shortflash onceper
second
Weak pilotsignal
onlastcall for heat.
Twoflash, three second
pause
Pressureswitch not
working-closed
position.
Three flash, three second
pause
Pressureswitch or
blower temp.
switch notworking
-openposition.
Four flash, three second
pause
Excessivetank
temperature.
System mustbe
reset.
Fiveflash, three second
pause
Undesired-false
pilotflamepresent.
Troubleshooting
LED Status
Stand-by mode,
Waitingfor call for
heat(nofault)
Control Status Service
Procedure
Probable Cause
Temperaturedemand issatisfied.
Normal operation.
Adjustthermostatto
temp level.
Tank temperaturebelow setpoint ofthermostat.
Normal operation.
Adjustthermostatto
temp level.
1. Unstable pilot.
2. Pilottubeblocked or restricted.
3. Oxidationbuild up onpilotelectrode.
4. Wiredamagetopilotassembly or bad
connectionatgas valve.
1-4. Page19
1. Pressureswitch tubingkinked or blocked.
2. Blocked pressuretap onswitch or blower.
3. Faulty pressureswitch.
Page20
1. Vent blockageor improper vent configuration.
2. Pressureswitch tubingkinked or blocked.
3. Faulty pressureswitch.
4. Blower notspinningup tospeed.
5. Blower temp or exhausttemp too high.
6. Faulty blower temperatureswitch.
1. Check vent or vent
tables
2&3. Page20
4. Page22
5&6Page23
1. Thermal well sensor outofcalibration.
2. Faulty gas control.
3. Plumbingleak
1-2. Replacegas
control, page26
1. Pilotvalvestuck inopenposition.Replacegas control,
page26
None, control LED noton
or flashing
Noelectrical
power
Control power switch in“OFF”position.
Supply voltageinterrupted. Turnpower on.
Page12
Observe green LED indicator on Electronic gas
control. Error flash codes are displayed with a
three second pause before repeating. Check
and repair the system as noted in the
troubleshooting table below.
GreenLED
Indicator
12

Six-four flash, three
second pause
Undesired-false
pilotflamesensed.
System autoresets.
Sevenflash, three second
pause
Simulated Resistive
DeviceHarness out
ofspecification.
Eight-oneflash, three
second pause
Simulated Resistive
DeviceHarness
specificationcheck.
Thermal well
sensor damaged or
unplugged
Eight-three flash, three
second pause Gas valve
electronicsfault
detected
LED Status Control Status Service
Procedure
Probable Cause
Pilotvalvestuck inopenposition.Replacegas control,
page26
1. Simulated resistivedeviceoutofspecification.
2. Resettable thermal switch open.
1. Page28
2. Page29
1. Simulated resistivedeviceoutofspecification.
2. Resettable thermal switch open.
1. Page28
2. Page29
1. Damagetothermal well wire.
2. Thermal well sensor resistanceoutofrange.
1&2. Replacegas
control, page26
1. Control needstobereset.
2. Control iswetor physically damaged.
1. Interruptpower
supply
2. Replacegas control,
page26
Eight-four flash, three
second pause
Gas valvefault
detected.
1. Control needstobereset.
2. Control iswetor physically damaged.
1. Interruptpower
supply
2. Replacegas control,
page26
Troubleshooting
Six-three flash, three
second pause
Pilotflame
extinguished.
System autoresets.
1. Unstable pilot.
2. Pilottubeblocked or restricted.
3. Oxidationbuild up onpilotelectrode.
4. Wiredamagetopilotassembly or bad
connectionatgas valve.
5. Insufficient combustionair.
6. Gas pressureisoutofspecification.
1-4. Page16
5. Refer toinstallation
manual
Page13
Six-twoflash, three
second pause
Pressureswitch or
blower temp switch
opened during
burner operation.
System autoresets.
1. Check vent or vent
tables
2&3. Page20
4. Refer toventing
sectionof
installationmanual
5. Page22
6&7. Page23
1. Vent blockageor improper vent configuration.
2. Pressureswitch tubingkinked or blocked.
3. Faulty pressureswitch.
4. Vent terminationbeingaffected by wind.
5. Blower notspinningup tospeed.
6. Blower temp or exhausttemp too high.
7. Faulty blower temperatureswitch.
Six-oneflash, three
second pause
Failed tolightpilot.
System autoresets.
1. Unstable pilot.
2. Pilottubeblocked or restricted.
3. Oxidationbuild up onpilotelectrode.
4. Wiredamagetopilotassembly or bad
connectionatgas valve.
1-4. Page16
13

Step 5. Fully inspectburnerdoorand rightsideinnerdoorgaskets forthefollowing:
>Tears >Otherimperfectionsthatwill inhibitproperseal
>Missing Material>Gasketadhesion to innerdoor
>Cracks>Materiallefton combustion chamber(around opening)
>Dirt ordebris
If thegasketisnoteffectedbyany of theabove,gasketreplacementisnotrequired. If replacementis
required, proceedtoInnerDoor GasketReplacementProcedure.
Inner Door Removal Procedure
Step1. Position gas control power switch to the “OFF”
position and unplug heaterfrom wall outlet.
Step2.Removeouterjacketburneraccess door.
Step3. Removewireclip from main burnerfeedline.
Step 4. InnerDoorRemoval.
a)Disconnectthespark igniter/flamesensorwireand the
simulatedresistivedevicefrom thegascontrol (see photo 1).
b) Disconnectmain burnerfeed line(¾” wrench), pilottube
(7/16" wrench) and igniterwirefrom gascontrol (see photo2).
c) Remove(2)¼” hex drive screws from right side inner door
(see photo 3).
d) Remove(2)¼” hex drive screws from flange section of
innerdoor(see photo 3).
e)Remove(3) 1/4" hexdrivescrewsfrom burnerdoor
(see photos4&5). Theburnerdoorand burnerare
one-piece.
f) Removeburnerand innerdoorand inspectperstep5.
1
2
3
4
5
Simulated Resistive
Device
Spark Igniter/
Flame Sensor
Wire
Main Burner
Feedline
Pilot Tube
Igniter Wire
Right Side
Hex Drive
Screws
FlangeHex
Drive Screws
Burner Door
Hex Drive
Screws
Position #1
Position #2
Position #3
UTTWSERVICE PROCEDURE I
Burner and Inner Door/Gasket Removal,
Inspection, Replacement and Reinstallation
Page14
Gas Control shown in the “OFF” position
R
14

Re-installation of Inner Door With Gasket
WARNING
Strippedfastener connections mayallow
for seal breach of inner door. A seal
breach mayresult in a fire or explosion
causingpropertydamage,personal injury
or death. Do not over tighten screws in
steps 9,11 and12.
If a fastener connection is stripped,
contact the manufacturer listedon the
water heater ratingplate.
Step8. Cleanany residualgasketresidueorotherdebris
from combustion chambersurfacebefore
re-installing theinnerdoor/gasketassembly.
Step9. Placetheburnerdoorintoposition first.Tighten
thefeed linenuttothegascontrol. Use the ¼”
hexdrivescrewwithoutthebuilt-in washerto
secureburnerdoortothechamberatposition #1.
Use the ¼” hex drive screws with the built-in
washertosecurethedooratpositions#2&#3
(see photos4&5, on page14).
DO NOT OVERTIGHTEN SCREWS.
Inner Door Gasket Replacement Procedure
WARNING
If the information in these instructions is not
followedexactly, a fire or explosion mayresult causing
propertydamage,personal injuryor death.
Step6. Afterinspection of innerdoorasnotedinstep 5, completely removegasketand adhesiveresiduefrom burner
doorand rightsideinnerdoorasneeded.
Step7. UseRTVsealant(recommendedbeadsize1/8") tosecuretheinnerdoorgaskettotheinnerdoorsections
(right&burner). Theburnerdoorgasketmust beslicedinthelocation shown on theillustration below in
ordertoslidethegasketovertheburnerventuri. Referto illustration below forproperRTVsealant
application. Notetheoverlap configuration in theflangearea of theinnerdoor.Ensurethatthechamferof
thegasketfacesoutward. Settheflangesection first,thiswill help toachievetheproperoverlapposition.
UTTWSERVICE PROCEDURE I
Burner and Inner Door/Gasket Removal,
Inspection, Replacement and Reinstallation
Page15
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15

Step 11. Firmly place right side inner door flange against the burner door flange and secure with two ¼” drive
screwsfrom step4d(see photo 7). DO NOT OVER TIGHTEN SCREWS.
Step12. Align rightsideinnerdoorto combustion chamberand verify thefastenerholesof thecombustion
chamberarealignedwiththerightsideinnerdoorslottedopening (see photo 7). Verify sealintegrityaround
combustion opening. Securerightsideinnerdoorusing 1/4” hex drive screws from step 4c.
DO NOT OVER TIGHTEN SCREWS.Verify bothburnerand rightsidesof theinnerdoorareproperly
positionedand sealedagainst thecombustion chamber.
Step 13. Reconnectspark igniter/flamesensorwireand simulatedresistivedevicetothegascontrol (See photos1&2
on page14).
Step 14. Reconnectthepilottubetothegascontrol and tighten.
Step 15. Replaceouterjacketburneraccess door.
Step 16. Toresumeoperation follow theinstructionslocatedonthelighting instruction labelo
rthelighting instructions
locatedintheinstallation and operation manual.
Position Thermopile Wire,
Pilot Tube and Igniter Wire
Step 10. Position thermopilewires, pilottubeand igniterwire
against burnerdoorflangegasket
(see photo 6).
Secure flange with ¼"
drive screws.
Verify threaded hole
alignment with slotted
openings in inner door.
7
6
UTTWSERVICE PROCEDURE I
Burner and Inner Door/Gasket Removal,
Inspection, Replacement and Reinstallation
Page16
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16

UTTWSERVICE PROCEDURE II
Burner Operation Inspection,
Cleaning and Replacement
Page17
Atperiodic intervals(notmorethan6months)avisualinspection should bemadeof themain burnerforproperoperation
and toinsureno debrisisaccumulating.
Main burnershould lightsmoothly from pilotand burnwithablueflamewithaminimum of yellow tips.After
approximately 5 minutesof operation theburnerscreen will becomeradiantand theflamewill softenand turnorange.If
theburnerscreendoesnotbecomeradiantafter5 minutesof operation itmust becleaned(see burnercleaning procedure
below).
Main burnermust befree from any debrisaccumulation thatmayaffectburneroperation (see burnercleaning procedure
below).
DANGER
Under no circumstances shall flammablematerialsbe used or stored in thevicinity ofthewater heater.If
flammablevapors are present, a fire or explosion may result causingproperty damage,personal injuryor
death.
WARNING
Inner door andburner components maybe HOT when performingthis operation. Take
necessaryprecaution to prevent personal injury.
¼” Hex Drive Manifold
Cover Screws
¼” Hex Drive Manifold
Bracket Screws
Manifold Cover
Main Burner Inspection,Cleaningand Replacement
Burner Cleaning
Step1. Removeburnerand innerdoorassembly perSERVICE PROCEDURE I, steps3through 4.
Step2.Removemanifold coverfrom burnerinnerdoorby removing (2)¼” hex drive screws and then sliding
manifold covertotheright.Useastiff brush, compressedairand/orshop vacuum toremoveany debris
build up from themanifold mount.
Step3. Removemanifold brackets from burnerby removing (4) ¼” hex drive screws.
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UTTWSERVICE PROCEDURE II
Burner Operation Inspection,
Cleaning and Replacement
Page18
Step6. Disconnect(unscrew) manifold brackets from main
burnerorifices.
Step7. Removemain burnerorificefrom feed line(1/2"
wrench). Inspectand cleanifnecessary
Step8. Removepilotassembly, referto SERVICE PROCEDURE III forcleaning and inspection.
Step9. Reassembleburner.
Step 10. Reinstall burnerand innerdoorperSERVICE PROCEDURE I, steps5through 16.
Step 11. Toresumeoperation, follow theinstructionslocatedonthelighting instruction labelorthelighting
instructionslocatedintheinstallation and operation manual.
Burner Cleaning (Continued)
Step4. Thoroughly inspectburnerscreenand burnerventurisand removeany loosedebrisaccumulation. Inspect
burnerscreenforany openingslargerthanthenormalscreenopenings.
Step5. Usecompressedairand/oravacuum toremoveany scaleorotherdebrisaccumulation from theburnerscreen
and venturis.
Burner Screen Burner Venturis
Manifold Brackets
Main Burner Orifices
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UTTWSERVICE PROCEDURE III
Pilot testing, Cleaning and Replacement
Page19
Pilot Assembly Inspection, Testing
and Replacement
Step1. Position gas control power switch to the “OFF”
position and unplug waterheaterfrom wall outlet.
Step2.Removeouterjacketdoor.
Step3. Removeburnerand rightsideof innerdoor
perSERVICE PROCEDURE I, steps
3and 4.
Step4. Removeburnerassembly from combustion chamber.
Step5. Removepilot/electrodeassembly from burner(¼" drivetool)
Step6. Inspectpilotforkinksorcracksin thepilottube.
If found, thepilotmust bereplaced.
Step7. Inspectpilotorifice:
a)Remove7/16" nutfrom bottom of pilotassembly.
b) Removepilottubeand pilotorifice.
c) inspectpilotorificeforblockage,must becleanedorreplaced.
Step8. Install pilot/electrodeassembly toburner,securewithscrewfrom step5.
Step9. Install burnerand innerdoorperSERVICE PROCEDURE I, steps5through 16.
Step 10. Toresumeoperation follow theinstructionslocatedonthelighting instruction labelorthelighting instructions
locatedintheinstallation and operation manual.
7/16"Pilot
AssemblyNut
Gas Control shown in the “OFF” position
Pilot
Location
¼”Hex Drive
Pilot Screw
Pilot Orifice
Pilot Tube
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UTTWSERVICE PROCEDURE IV
Pressure Switch Testing and
Replacement
Pressure Switch Testing WARNING
115volt potential exposure. Use caution
makingvoltage checks to avoidpersonal injury.
Step1. Position gascontrol powerswitch to
the “OFF” position.
Step2.Removethethree screws(Phillipsscrewdriver)from control access coveron blowerassembly and
removecover(see photos1and 2).
Step3. Carefully removepressureswitch from blowerhousing (see photo 3).
3
Use amulti-meter set to the
ohms setting.With blower off,
check across pressure
switch terminals.
Are switch contacts open?
(no electrical continuity)
Check tubing and pressure tap
on switch for blockage.
Is there blockage?
Replace switch
(see page21)
Position gas valve power
switch to the “ON” position
and adjust thermostat
to call for heat,
this will start the blower.
Check with multi-meter, do
pressure switch contacts close
with blower running?
With steps 1,2 &3 complete,
disconnect wire leads from
pressure switch.
Y
N
Y
N
Switch contacts are OK.
See safety circuit trace
(page31)
Is vent
system
blocked
NSee blower testing
(page22)
Is blower OK?
Clear blockage
Y
N
Y
N
Correct blower
problem.
Pressure Switch
Slide pressure switch in direction of
arrow while tilting slightly away
from blower housing.
Is vent system length
within vent table
specifications
listed on page7
Y
Reconfigure vent
system to be
compliant with
vent tables.
N
Y
Pressure switch
wire leads
Page20
Check tubing and
pressure tap on
switch for blockage.
Is there blockage?
N
Y
Control
Access Cover
Screws
1
2
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