Bradford White UCG100H399 User manual

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Manual 238-51306-00A REV 12/14
SERVICE
MANUAL
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualified service providers)
Effective: December, 2014
ECO 7956
Models Covered
by This Manual:
UCG100H399*N
(*) Denotes Warranty Years
Ultra Low NOx Atmospheric Vent
Water Heaters with Direct Spark Ignition

2
Ultra Low NOx Atmospheric Vent Water Heaters
with Direct Spark Ignition
Table of Contents
Introduction...................................................................................................................3 
How to Use This Manual ..............................................................................................4
Tools Required for Service...........................................................................................4
Features .......................................................................................................................5
Specifications ...............................................................................................................6
Sequence of Operation ................................................................................................9
Troubleshooting.......................................................................................................... 11
Service Procedure I: Thermostat Circuit Testing and Replacement..........................16
Service Procedure II: Combustion System Testing and Replacement......................21
Service Procedure III: Burner Tube Inspection and Replacement ............................25
Service Procedure IV: Gas Valve Replacement........................................................27
Service Procedure V: Blower Testing and Replacement ..........................................28
Service Procedure VI: Flame Sensor Testing and Replacement ..............................30
Service Procedure VII: Spark Rod Gap Adjustment and Replacement.....................32
Service Procedure VIII: Ignition Module/Control Board Replacement....................... 34
Service Procedure IX: Blocked Vent Switch Inspection and Replacement ...............35
Service Procedure X: Anode Inspection and Replacement ......................................36
Service Procedure XI: Display Module Replacement................................................37
Service Procedure XII: Transformer Replacement....................................................38
Water Heater Installation Check list ........................................................................... 39
Water Heater Service Report ..................................................................................... 40
Parts List ....................................................................................................................41
Glossary of Terms ......................................................................................................44
Notes..........................................................................................................................44
2

SAVE THISMANUAL FOR FUTURE REFERENCE REV 12/14 238-51306-00A
Introduction
The Bradford White Ultra Low NOx Atmospheric Vent Water Heater is designed to deliver a
remarkableamount of hot water at 82% thermal efficiency in aquiet running unit with atop exhaust
vent connection that allows for installation in existing locations. Whilethis unit is vented
atmosphericallythere is no damper required to maintain heat loss during off cycle. Several
technologicallyadvanced design features are incorporated that will require additional knowledge on
the part of the qualified service provider. The information in this manual will instruct service and
maintenance professionalson the function, proper diagnosis and repair of The Bradford White Ultra
Low NOx Atmospheric Vent Water Heater.
The Bradford White Ultra Low NOx Atmospheric Vent Water Heater uses an ultra low NOx premix
power burner located at the top of the water heater to direct aturbulent flame down into the water
backed combustion chamber. This turbulence causes athorough mixing of gas and air for optimum
combustion. The combustion gases then travel through atwo pass flue system keeping the gases
moving at ahigh velocity. The combination of high turbulence and velocity results in an optimum
transfer of heat from the flue gases into the water.
Burner operation is controlled using an electronic ignition module. The modulemonitors the status of
the electronic thermostat, blocked vent limit switch, flame sensor to control output voltage to blower
motor, spark rod and gas valve. The modulecontains programming which determines the sequence
of operation and timings for purge periods, trial for ignition, flame sensing and lockout. The module
will also provide diagnostic information to helpin determining the cause of system lockouts.
The contents in this manual are detailed informational toolsto assist in the proper diagnosis of the
Ultra Low NOx Atmospheric Vent Water Heater operational faults. Please read this service manual
completelyand record as much information regarding the Ultra Low NOx Atmospheric Vent Water
Heater operation and installation specifics related to any concerns.
3

4
How to Use ThisManual
Itis intended for this manual to be used by qualified service personnel for the primary purpose of
troubleshooting analysis and repair of the Bradford White UCG100H399. Understanding the
sequence of operation section of this manual will contribute greatlyto troubleshooting this product.
An “Installation Check List” is shown towards the end of this manual. Compare the installation against
the installation check list to confirm all requirements are met.
A“Service Report” is shown towards the end of this manual. Completing this form will assist in the
troubleshooting efforts. Shouldyou need to call for technical support, please provide the information
shown on this form to the support technician to helpensure accurate troubleshooting.
Troubleshooting begins with “System Observation” to determine failure mode as indicated by the
error code on the system display. Troubleshooting continues with “Failure Modes and Probable
Cause” directing the service provider to aseries of test procedures to determine root cause of failure.
Component replacement procedures directlyfollow the test procedures for agiven component.
Insome difficultto diagnose conditions, it may be necessary to isolate the heater from the vent
system to determine root cause.
Contact Technical support immediatelyif diagnosis is not determined using the methods described in
this service manual.
ToolsRequired for Service
Manometer: Two types available, aliquid “U” tube type or adigital (magna-helic) type. This device is
used to measure gas and/or air pressures and vacuum.
Multi-Meter: Adigital type is stronglyrecommended. 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.
Thermometer: Used to measure water temperature. An accurate thermometer is recommended.
Water Pressure Gage: Used to measure water supplypressure. Also used to determine tank
pressure by adapting to the drain valve of the heater.
Jumper Leads: Alength of wire (12" min.) with alligator clip at both ends.
Various Hand Tools: Pipe wrench, channel locks, open end wrench set, 12" crescent wrench, Allen
wrench set, torx bit set, screw drivers (common & phillips), long reach (12") magnetic tip phillips head
screw driver #2tip, ¼" nut driver, pliers (common & needlenose), socket set including a1-1/16 deep
well socket, wire cutters, wire strippers, wire crimpers, torpedo level, small shop vac, step ladder, and
flashlight.
4

5
Features
Features of Honeywell Integrated Control System

xAttractive digital water heater display on control panel for setting and displaying the temperature
setpoint. Pressing temperature UP and DOWN buttons changes the temperature setpoint.
Temperature format may be displayed in °F or °C.
xSinglecontrol board with plug in wiring controlstemperature, ignition, and blower operation.
xReduced number of parts for servicing and wiring.
xPlug in wiring reduces chance of miswiring.
xBurner ignition with direct spark ignition - Ahigh voltage spark jumps from the spark rod to the
burner surface to ignite the gas. Eliminates burned out hot surface igniter replacements.
xWater heater display will show diagnostic codes in the event the water heater needs servicing.
Aids in diagnosing and servicing the water heater.
xWater heater display can show previous error code history to further aid in servicing the water
heater.
5

6
Specifications
Model Description Dimensions (INCHES)
Model No.
Input
Rate
BTU/h
Storage
Capacity
U.S.
Gallons
A
Floor
to
Top
of
Vent
B
Vent
Dia.
C
Floor
to
Cold
Water
Conn.
D
Floor
to
T&P
E
Floor
to Hot
Water
Conn.
F
Floor
to Top
of
Water
Heater
G
Floor
to
Gas
Conn.
H
Depth
J
Jacket
Dia.
K
Floor
to
Top
Conn.
Water
Conn.
Dia.
Gas
Conn.
Dia.
Relief
Valve
Open
Shipping
Weight
(lbs)
UCG100H399 399,000 100 77 ¼810 52 ½ 55 ½ 69 ¾ 63 ¼30 28 ¼63 ¼1½ ¾ 1657
Model Description Dimensions (MM)
Model No.
Input
Rate
KW
Storage
Capacity
Liters
A
Floor
to
Top
of
Vent
B
Vent
Dia.
C
Floor
to
Cold
Water
Conn.
D
Floor
to
T&P
E
Floor
to Hot
Water
Conn.
F
Floor
to Top
of
Water
Heater
G
Floor
to
Gas
Conn.
H
Depth
J
Jacket
Dia.
K
Floor
to
Top
Conn.
Water
Conn.
Dia.
Gas
Conn.
Dia.
Relief
Valve
Open
Shipping
Weight
(kg)
UCG100H399 117.2371 1962 203 254 1334 1410 1772 1607 762 718 1607 38 19 25 297
6

7
Specifications
Power SupplyDedicated 120 VAC, 60Hz, 15A GFI
Gas SupplyMinimum 1” Nat
(Schedule40black iron pipe recommended)
Approved gas Type Natural. Unit must match gas type supplied
Gas Pressure (Nat.) 14.0” W.C. maximum static, 4.5” W.C. minimum running
(recommend 7.0” W.C. min running)
Venting System
AtmosphericallyVented, Type BVenting system or
approved chimney. Follow the current National Fuel
Gas Code requirements or in Canada, the Natural Gas
and Propane Installation Code.
Minimum Clearance for
Servicing 18” from top, 24” from front, 4” sides and rear.
Maximum Water Supply
Pressure 150 PSI
Thermostat Sensor
11,900 Ohms @ 70°F, ECO opens @ 207°F Max.
Redundant sensor for ECO. Sensor inside well for easy
replacement of sensor.
Control Display
Digital display, 24 volts. temperature Range: 70-180
degree F. Used to set tank temperature (deg. F or deg.
C), show operating status, display error codes, error
code history, limit maximum setpoint temperature.
Control Board
Operates from 24 voltfrom transformer. Controlstank
temperature, ignition functions, combustion blower. See
ignition timings in sequence of operation for Integrated
Control.
Transformer 120 VAC primary, 24 VAC secondary, 40VA.
Spark Rod Igniter 0.22” nominal gap to the burner surface.
Flame Sensor Output Minimum 1micro amp. Typical range 5to 30 micro
amps.
Gas Valve Negative regulation, 24 VAC, ½” PSI max., 4.5” W.C.
minimum running inlet.
Vent Safety Switch Normallyclosed, opens @ 240°F, manual reset.
Blower 120 VAC, 60 Hz, 1.5-3.5amps, 8000 RPM
Combustion LevelsCO2:8-11%, CO: less than 0.04% (400 PPM) air free

7

8
Specifications
Vent Tables
(Intake Only)
Model Number Max Intake Vent Length (feet) 3" Max Intake Vent Length (feet) 4"
UCG100H399 2550
WARNING!The UCG100H399 model is not approved for 2 inch diameter vent pipe. Venting with 2 inch pipe may result
in damage to the water heater or cause an unsafe condition. DO NOTuse 2 inch Vent Air Intake Pipe!
Determining required intake vent length
1. Determine the total length of straight vent pipe (in feet) required for the intake.
2. Add 5feet of venting for every 90° elbow.
3. Add 2 ½feet of venting for every 45° elbow.
4. Total vent length cannot exceed “Max Intake Vent Length” on the venting tableshown above.
Exampleof Total Intake Vent Length for UCG100H399 installation:
A3” venting system has atotal of two 90-degree elbows and atotal straight pipe length of 10 feet.
Equivalent vent length for elbows: 2 x5feet = 10 feet.
Total equivalent vent distance = 10 feet + 10 feet = 20 feet total equivalent vent length. Thisisbelow
the maximum allowed distance of 25 feet for thismodel using 3” vent.
8

9
Sequence of Operation
1. Thermostat callsfor heat.
2. Combustion blower starts.
3. Blower pre-purge period of 30 seconds.
4. Trial for Ignition. (5 seconds, 3trials).
a. Flame establishing period (3 seconds), gas valve opens, sparks from spark rod to burner surface to ignite
the gas.
b. Burner on, flame proving period (2 seconds). Requires aminimum of 1.0microamp through flame sense
rod to prove flame.
c. Ifthe blocked vent safety switch contacts (normallyclosed) opens, then the ignition sequence will not
start and an error code 67 (Vent safety switch failed to close/open) will be shown on the display.
5. Steady State Operation: Burner continues to operate until:
a. Thermostat circuit opens, gas valve closes, blower continues to operate for 30 second post-purge period.
b. Ifthe normallyclosed blocked vent safety switch opens, the gas valve closes, the blower continues to
operate indefinitelyand error code 67 will be displayed after acoupleminutes (up to 5minutes) with
“Service Needed.”
6. Thermostat satisfied.
7. Gas valve closes, burner extinguished.
8. Blower post purge for 30 seconds.
9

10
Sequence of Operation
LockoutConditions
The system will go into lock out mode for the following reasons:
1. ERROR CODE110
a. Control board will go into “Soft Lockout”if the main burner cannot be lit or failsto prove flame after 3
ignition trials. The water heater display indicates alockout condition by showing an error code number
110 with “Service Needed”in the control display window. Refer to error codes in the diagnostic section of
this Service Manual. Ina“Soft Lockout”condition, the control will wait for 15 minutes and then make 3
more attempts to light the main burners. Soft lockout reset is accomplished by depressing the lower right
button under “Reset”for 3seconds.
2. ERROR CODE80
a. Ifthe top of the tank shouldexceed 207°F,then the high limit control will shut off the burner and the water
heater will go into a“Hard Lockout.”Error code 80 will be shown in the water heater display. The control
can onlybe reset in the “Service Mode,”which is detailed in the “Troubleshooting”section of this Service
Manual.
3. ERROR CODE67
a. Ifthe vent safety switch located on the draft hood shouldopen, the gas valve will close, the blower will
post-purge and error code 67 will appear on the display. The lockout condition will reset once the
problem is corrected and the switch reset. Refer to “Vent Safety Switch Testing and Replacement”in this
Service Manual.
CONNECTION/WIRING DIAGRAM
10

11
120voltpotential exposure. Use caution making voltage checks
to avoid personal injury.
WARNING
Use caution not to damage connectors when making voltage
measurements or jumping terminals
CAUTION
Troubleshooting
System Observation for Modelswith Direct Spark Ignition
Water Heater Fault: Water heater does not operate
Display Error Code: Water heater display does not
operate - blank display
Check main power supplyto water heater –
fuse, circuit breaker, plug receptacle, line cord or
wiring to water heater.
Check to make sure switch on front of control
panel is in the ON position.
Verif
yp
rimar
y
volta
g
eat the transformer.
Refer to control board illustration.
Voltage at transformer across black and
white wires shouldbe 110-120VAC.
Check line cord with voltmeter. Replace
line cord if defective.
Verif
y
secondar
y
volta
g
eat the control board.
Refer to control board illustration.
Voltage at connector location J8 across
blue and yellow wires shouldbe 24VAC.
Ifnot, check transformer. Replace
transformer if defective.
Does water heater display
operate? Increase thermostat
setting if tank is warm.
Is24VAC present between
RED and BLACK wire pin
connections on the back of
control display?
Display operates-See next page. Display operates-See next page.
Replace control board.
Check wire
harness for proper
continuity.
Check wires for proper
termination to control display.
Are wire terminations connected
properlyto control display?
Replace
control
board.
Make proper wire
terminations.
Y
Y
Y
Y
N
N
NN
Yellow &
Blue
wires.
Black &
White
wires.
11

12
Troubleshooting
120 voltpotential exposure. Use caution making
voltage checks to avoid personal injury.
WARNING
Use caution not to damage connectors when
making voltage measurements or jumping terminals
CAUTION
From previous page.
Does combustion
blower operate?
Error code #67 on display. Measure voltage
between black and white wires, of the 3wire
harness, at the blower (make sure the
control display shows “heating” in the status
mode, if not increase the setpoint). Isthere
110-120 VAC?
Replace power cord/blower harness if
display shows “heating” and no voltage
is present to the blower.
Check that the 5wire blower
modulation harness is plugged
in to the blower
Plug in the wire harness. (Note: If
this harness is unplugged blower
will run constantl
y
.
)
Can sparking be
seen/heard at the spark
rod to the burner?
Remove high voltage wire connected at
the spark rod and holdapproximately¼”
from metal ground with insulated pliers
during the ignition cycle(3 second spark
trial period). Isthere spark to ground?
Check resistance of high voltage
cable. Resistance shouldbe 0-1
ohms. Ifresistance is high, replace
spark cable. Ifspark cableis good,
replace control board.
Check continuity of spark rod and spark
rod gap to burner. (see section “Spark
Rod Gap Adjustment.”
Does main burner light?
Error code #110 on display.
See main burner lights, no
flame signal in section
“Combustion System Testing
and Replacement.”
(See “Combustion System
Testing and Replacement”).
Does burner continue until
thermostat set point is
reached? See setting
display in Service Mode
and displaying
temperature sensors.
Does blower post-purge for
30 seconds?
System okay
Check to see if control display shows any other error codes
(pressure switch, vent safety switch, or high limit). Ifso, refer to
the appropriate section for testing and replacement.
Replace
Blower
Replace
Control
Module
Measure voltage
between yellow and
green wires. Isthere
17-30 VDC?
NN
N
N
N
N
N
N
Y
Y
Y
Y
Y
Y
Y
Y
Y
12

13
Troubleshooting
Step 1: Press and holdthe lower right button under “Next”in the lower right display for at least 3seconds.
Step 2: The display will show the flame sense current in microamps when the burner is operating.
Step 3: Press the lower right “Next”button and the display will show flash and show the number ofany Alert codes.
These are not currentlyused.
WARNING
The following procedure is for service and installation personnel only. Resetting lockout conditions
without correcting the malfunction can resultin ahazardous condition.
13

14
Troubleshooting
Step 4: Press lower right “Next”button and the display will flash and show the number ofany Lockout codes.
Step 5: Press lower right “Next”button and the display will show the temperature sensor reading.
Step 6: End ofscreens in Diagnostic Mode. Press “Done”button on lower leftto exit Diagnostic Mode back to DHW
setpoint in the User Mode.
NOTICE
The screens will stay in the Diagnostic Mode for 12.5minutes after the last button press for viewing
unless “Done”button is pressed to exit Diagnostic Mode.
14

15
Troubleshooting
DIAGNOSTICERROR CODES AND TROUBLESHOOTING PROCEDURES FOR EF100T399 MODELS WITH
HONEYWELL LOW FIRE START CONTROL SYSTEM
Error Code Definition ofCode Cause ofProblem and Actions Taken to Correct
Nocode –
blank display
xCheck power supplyto the water heater.
xMake sure water heater is plugged in and the breaker is on.
xCheck ifthere is 120volts power supplyto the LINEconnections on the
control board.
xIf120volts is present,check for 24 volts output to SECONDARY
terminalson the Control Board.
xCheck for loose wires,defective transformer.
xCheck wire harness connections from display to the control board.
3-48,58-60Internal Faults
xVerifywiring to the control board with wiring diagram.
xCheck power supplyto make sure voltage and frequency is correct.
xCheck for 24 volts from the transformer to the control board.
xReset modulebyinterrupting power or pressing the reset button on the
module.
49Voltage too low or high
xMeasure the incoming line voltage.
xVoltage shouldbe115-125volts.
xIfthe voltage is not within this range or there is drastic fluctuation,then
have the incoming power supplychecked.
xIfthe line voltage is satisfactory,check the output from the transformer
to make sure it is 22-26volts.
xReplace transformer or wiring ifdefective.
53 AC Inputs phase
reversed
xCheck the moduleand display connections.
xCheck the modulepower supplyand make sure that frequency,voltage
and VA capacity ofthe transformer meet specifications.
xCheck to make sure the wiring connections on the control modulefrom
terminalsJ4-10and J8-2 are connected together.
62 Fan speed not proved
xCheck the blower modulation wire harness connection from the blower
to the control moduleat J2 connection.
xMake sure the pin terminalsmake solid contact.
xMeasure the resistance ofeach wire in the wire harness from the
terminal ends.
xReplace wire harness ifdefective.
xCheck ifthere is 17-30volts DC between the yellow and green wires on
the blower 5wire harness.
xCheck ifthere is 17-30VDC between the yellow and green wires on the
blower 5wire harness.
67 ILK Off (Interlock Off)
xCheck wiring to the normallyclosed blocked vent safety.
xUse avoltmeter to find out ifthe blocked vent safety switch has
opened.
xIfso,determine the cause (blocked vent terminal,recirculation).
xIflimit switch is closed,check wiring for shorts.
xMeasure continuity.
xIflimit switch and wiring check O.K.,replace control module.
Troubleshooting
15

16
Service Procedure I:
80 High Limit (Overheat
Condition)
xCheck the wiring from the sensor to the control module.
xMeasure the resistance ofeach outside wire to the center wire.
xIfeither outside wire has amuch different resistance reading,replace
the sensor.
xMake sure the sensor is securelyheldinside the well with the clip.
xIfthe problem persists and the sensor and wiring check O.K.,then
replace the control module.
93DHW/TEMP
Sensor Fault
xCheck the sensor wire harness from the sensor to the control module.
xMake sure there are no loose connections to the control plug.
xCheck the resistance reading from each ofthe outside wires to the
center (common)wire.
xIfthe ohm readings are not fairlyclose,replace the sensor.
xReplace the control moduleifthe problem persists and the sensor and
wire connections are not defective.
105Flame detected out of
sequence
xCheck to see ifflame is present inside the combustion chamber before
or after the ignition cycle.
xIfso,check to make sure the gas valve is wired correctly.
xCheck for voltage at the gas valve connection.
xReplace the gas valve ifdefective.
xIfno flame is visibleoutside ofthe ignition sequence/run cycle,then
make sure the flame sensor is wired to the correct terminal.
xMake sure the ignition cableis not crossing the flame sensor wire or
ignition ground wires.
xIfproblem persists and all other checks have been verified,replace the
control module.
110Ignition Failure
Occurred
xBurner failed to light or stay lit after 3retries.
xHoldcondition – will reattempt ignition after 15minute waiting period.
xCheck gas valve wiring and gas valve operation during the ignition
cycle.
xIfburner lights but quicklygoes out,check the flame sensor wire or the
flame sensor.
xIfthe flame sensor rod is badlycorroded with deposits,clean with
sandpaper or replace.
xCheck the inlet gas supplyto make sure the pressure is sufficient and
does not drop after the gas valve opens.
xMake sure the combustion blower is operating during the ignition and
run cycle.
xCheck the venting system to make sure the inlet and exhaust terminals
and venting system is not blocked.
122 Light-off Rate Proving
Failed
xIfblower speed is not verified from the PWM(Pulse Width Modulation)
signal within 5minutes,the previouslydescribed error code “62”
changes from aholdcondition to this lockout code condition.
xCheck the harness and pin terminalsfor agood connection to the
control module.
xReplace the control moduleifthe wire harness is good.
137 ILK Open
(Interlock Open)
xCheck ifblocked vent safety switch is open.
xIfswitch checks O.K.,replace control module
16

17
Thermostat CircuitTesting and Replacement

IMPORTANT NOTE: This procedure assumes acool tank.
120voltpotential exposure. Use caution making
voltage checks to avoid personal injury.
WARNING
Use caution not to damage connectors when
making voltage measurements or jumping
terminals
CAUTION
Condition: Water heater notoperating.
Display shows error code “93” (sensor
reading faulty)
N
Unplug or disconnect electrical power to the water heater.
Check continuity of wire harness to sensor. Resistance of
harness shouldbe close to 0ohms. Replace wire harness
if high resistance is measured (over .5ohms). Check
wires for intermittent connections, shorts, frayed
insulation. Replace if necessary.
Ifwire harness is O.K.,check sensor resistance detailed
in “Appendix – A: sensor resistance at various
temperatures” at the end of the thermostat testing and
re
p
lacement section. Re
p
lace sensor if needed.
Turn power ON to water heater. Run water heater through
heating cycleand verify proper operation. Sensor
temperature can be viewed when burner shuts off (see
section on viewin
g
the dis
p
la
y
in “Service Mode”
)
.
Condition: Water heater notoperating. Display
shows error code “80” high water temperature
(
over 200 °F
)
.
WARNING
Do notreset the display fromthe hardlockout
state without correcting the cause ofthe
overheatin
g
condition.
Turn power OFF. Draw water to cool tank below 120°F
Check sensor. Sensor is heldin place with aclip fastened
to the well (see photo). Check sensor wire for potential
damage or breaks in the wire insulation. Isthe sensor fully
inserted into the well?
Ifsensor clip is damaged replace
clip. Replace sensor if damaged.
Check sensor resistance (see Sensor
Resistance Testing, following section).
Continued on
next page.
Y
Checking
continuity of
sensor
(disconnected
from control board.
Sensor shown fully
inserted into well
Sensor clip shown
properlyinstalled
17

18
Service Procedure I:
Thermostat Circuit Testing and Replacement
Donot operate waterheaterwithout verifying
that the overheatingcondition has been
corrected.
WARNING
Condition:Water heater not operating. Display
shows error code“80” high water temperature
(over 200 °F) (continued from previous page).
Once cause of overheating condition has been diagnosed
and corrected, the control may be reset.
xReconnect and switch on power to the water heater.
xPress button under “Reset” and holdfor 3seconds.
xSet thermostat to the desired setting.
xWater heater will start.
xMonitor temperatures for one complete heating cyclemaking sure
the maximum tank tem
p
erature remains below 200 °F.
18

19
Service Procedure I:
Thermostat Circuit Testing and Replacement
APPENDIX-A
Sensor Resistance at Various Temperatures
Be careful when making voltagemeasurements or jumping terminals not todamageor deform connectors or
connector pins.
Draw water fromthe T&Pvalve. Compare temperature with temperature ohmschart below.
Example: Ifthe temperature is 84°F, then the resistance through the sensor wouldbe 8449 (see shaded area).
Note: Sensor resistance increases as the temperature falls.
InDegrees F
°F 0123456789
40 26109 25400 24712 24045 23399 22771 22163 21573 21000 20445
50 19906 19383 18876 18383 17905 17440 16990 16553 16128 15715
60 15314 14925 14548 14180 13823 13477 13140 12812 12494 12185
70 11884 11592 11308 11032 10763 10502 10248 10000 9760 9526
80 9299 9078 8862 8653 8449 8250 8057 7869 7685 7507
90 7333 7165 7000 6839 6683 6531 6383 6238 6098 5961
100 5827 5697 5570 5446 5326 5208 5094 4982 4873 4767
110 4663 4562 4464 4368 4274 4183 4094 4006 3922 3839
120 3758 3679 3602 3527 3453 3382 3312 3244 3177 3112
130 3048 2986 2925 2866 2808 2752 2697 2643 2590 2538
140 2488 2439 2391 2344 2298 2253 2209 2166 2124 2083
150 2043 2004 1966 1928 1891 1856 1820 1786 1753 1720
160 1688 1656 1625 1595 1566 1537 1509 1481 1454 1427
170 1402 1376 1351 1327 1303 1280 1257 1235 1213 1191
180 1170 1150 1129 1110 1090 1071 1053 1035 1017 999
190 982 965 949 933 917 901 886 871 857 842
200 828 814 801 788 775 762 749 737 725 713
InDegrees C
°C 0123456789
032648 31026 29495 28049 26682 25389 24166 23010 21915 20879
10 19898 18968 18088 17253 16461 15710 14998 14322 13680 13071
20 12492 11942 11419 10922 10450 10000 9572 9165 8778 8409
30 8057 7722 7403 7099 6808 8532 6268 6016 5775 5546
40 5327 5117 4917 4726 4543 4368 4201 4042 3889 3742
50 3602 3468 3340 3217 3099 2986 2878 2774 2675 2579
60 2488 2400 2316 2235 2157 2083 2011 1942 1876 1813
70 1752 1693 1637 1582 1530 1480 1432 1385 1340 1297
80 1256 1216 1177 1140 1105 1070 1037 1005 974 944
90 916 888 861 835 810 786 763 741 719 698
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120voltpotential exposure. Isolate the
appliance and reconfirm power is disconnected
using amulti-meter.
WARNING
Service Procedure I:
Thermostat Circuit Testing and Replacement
ThermostatSensor(Thermister)ReplacementProcedure
Step 1. Positionmainpower switch to “OFF”
Step 2. Disconnect (unplug) water heater from 120voltpower
source.
Step 3. Un-latch and remove top surround cover from top of
heater.
Step 4. Disconnect temperature sensor from control (see photos below).
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Step 5. Unclip sensor from well and pull sensor to remove,donot remove well (see picture).
Step 6. Install new sensor assemblyinto well and reinstall senor clip.
Step 7. Reconnect the sensor connector to the control boardand route the wire harness
throughthe same path that it was removed.
Step 8. Restore 120voltpower supplyand water supplyto water heater,check and repair anyleaks found. Confirm
proper operationfollowing the lighting instructionsonthe lighting instructionlabel or the lighting instruction
locatedinthe installationand operating instructionmanual.
Step 9. Replace surround cover ontop of heater.
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Sensor clip sown
properlyinstalled
Sensor shownfullyinserted
into well
Disconnect sensor
harness from
control board
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