Bradford White GX225S BN Series User manual

Save this manual for future reference
Manual 238-46647-00B
SERVICE
MANUAL
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualified service providers)
Models Covered
by This Manual:
GX225S*BN
GX155S*BN
25X78B*N
55X80B*N
M1XR65T*(BN,CX,SX)
MI75S*(BN,CX,SX)
M2XR75S*(BN,CX,SX)
MI100T*(BN,CX,SX)
65T65*(BN,CX,SX)
75T80*(BN,CX,SX)
C(S,D)W275T*(BN,CX,SX)
(*) Denotes Warranty Years
For Models Using White Rodgers,
Robertshaw and Honeywell Gas Control
Atmospheric Gas Water Heaters
(GX155S6BN Model Shown)

Table of Contents
Service
Page Procedure
Troubleshooting Chart White Rodgers and Robertshaw Gas Control 3 - - -
Troubleshooting Chart Honeywell Gas Control 4 - - -
Thermocouple Testing and Replacement White Rodgers and Robertshaw Gas Control 6 AG-I
Thermopile Testing and Replacement Honeywell Gas Control 7 AG-I
Pilot Assembly Inspection Cleaning and Replacement
White Rodgers and Robertshaw Gas Control 9 AG-II
Pilot Assembly Inspection Cleaning and Replacement Honeywell Gas Control 10 AG-II
Gas Control Testing and Replacement White Rodgers and Robertshaw 12 AG-III
Gas Control Replacement Honeywell 12 AG-III
Honeywell Thermowell Testing and Replacement 16 AG-III
Honeywell Gas Control and Thermowell Replacement 18 AG-III
Burner Operation Inspection, Adjustment, Cleaning and Replacement 20 AG-IV
Dip Tube and Anode Inspection and Replacement 23 AG-V
Page 2
2

Troubleshooting Chart
Symptom Probable Cause Corrective Action
Pilot will not light
1. Noincoming gas or too low gas
pressure.
2. Gas control knob set to wrong position.
3. Pilot lightbutton not being fully
depressed when attempting to lightpilot.
4. Pilot orificeor pilot tube isobstructed or
kinked.
1. Poor thermocoupleconnection at
gas control.
2. Thermocouplenot fully engaged inpilot
assembly bracket.
3. Pilot flameisnot fully enveloping the
thermocouple“hot” junction.
4. Weak or defectivethermocouple.
5. Open ECO on gas control.
6. Defectivemagnet ingas control.
Pilot will not
stay lit
when button isreleased
Pilot will light, butthe
mainburner will not
comeon
1. Gas Control set too low for desired water
temperature.
2. Gas Control temperatureissatisfied.
3. Insufficient gas supply or low gas
pressure.
4. Gas Control has widedifferential or isout
of calibration.
Pilot goes out
periodically (after
heating cycles, oncea
day, onceaweek etc.)
1. Insufficient combustion air supply.
2. Incorrect, clogged vent system/ vent
terminal or location.
3. Inconsistent gas supply or gas pressure.
Not enough hot water
1. Gas Control set too low for desired water
temperature.
2. Cold inlet water temperatureisvery cold.
3. High demand periods.
4. Incorrectly sized water heater for
application.
5. Gas Control isoutof calibration/not
functioning.
6. Outof spec dip tube isdiluting hot water
with cold water.
7. Integrated mixing deviceisset too low for
desired water temperature.
1. Turnon gas supply and/or check line
pressure.
2. Review lighting instruction. Set
gas control to correctposition.
3. Review lighting instruction. Fully depress
pilot lighting button.
4. Clean, repair or replace.
1. Check connection at gas control.
Proper tightness should be finger tightplus
¼ turn.
2. Inspectthermocoupleto ensurethat itis
fully engaged into pilot bracket.
3. Adjust tip of thermocoupleto be fully
engulfed by pilot flame.
4. Check thermocoupleand replaceif
necessary.
5. Check ECO continuity and replace
gas control ifnecessary.
6. Check magnet operation and replace
gas control ifnecessary.
1. Adjust temperaturedial on gas control.
2. Check temperaturedial setting on
gas control.
3. Check gas supply and line pressure.
4. Check gas control
for proper operation, replaceif
necessary.
1. Verify adequate combustion air isavailable
to theunit. Check and clear Jacket slot
openings of any dirt, dust, restrictions or
other obstructions.
2. Check venting for proper sizing and proper
operation
3. Check gas supply and line pressure.
1. Check dial on gas control.
2.Extremely cold water going into thewater
heater will decrease theamount of hot
water produced. Itmay be necessary to
temper incoming water supply.
3. Adjust high demand usage.
4. ContactPlumbing professional.
5. Check gas control
for proper operation, replaceif
necessary.
6. Inspectdip tube and replaceifnecessary.
7. Reset deviceusing theprocedure
intheinstructions included with thedevice.
Service
Procedure
1. See ServiceProcedure
AG-III, Page 12.
4. See ServiceProcedure
AG-II, Page 9.
4. See ServiceProcedure
AG-I, Page 6
5. See ServiceProcedure
AG-III, Page 12
6. See ServiceProcedure
AG-III, Page 12
2. See Installation &
operation manual.
3. See ServiceProcedure
AG-III, Page 12
4. See ServiceProcedure
AG-III, Page 12
3. See ServiceProcedure
AG-III, Page 12
5. See ServiceProcedure
AG-III, Page 12
6. See ServiceProcedure
AG-V, Page 23
Page 3
For ModelsUsing White Rodgersor Robertshaw Thermostat
3

Troubleshooting Chart
For ModelsUsing Honeywell Gas Control
Observe LED indicator on 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:
LED Status Control Status Probable Cause
Not on and/or
not flashingPilot flamemay not be present.
Gas control is in the“PILOT” position and
thepilot flameis detected.
One flash and athree
second pause.
LEDis on continuouslyGas control has recentlybeen turned to the
“OFF” position. Wait until LEDgoes out
before attempting to relight.
Two flashes and athree
second pause.
Weak pilot flamedetected. System will reset
when pilot flameis sufficient.
Three flashes and a
three second pause.
Tank temperature fault.
System will reset.
Pilot flameis not present.
Gas control is powered and waiting for theset
point knob to be turned to awater
temperature setting.
Gas control was turned to the“OFF” position.
1. Thermopilefailure
2. Unstablepilot.
3. Pilot tube blocked or restricted.
Thermowell sensor out of calibration.
Service
Procedure
1. Lite pilot per theinstructions
located on thelighting
instructions label or the
lighting instructions located in
theinstallation and operation
manual.
2. See Service
Procedure AG-I,
Page7.
Normal operation. Adjust gas
control set point knob to
desired temperature level.
1. Wait for LEDto goout.
2. Lite pilot per theinstructions
located on thelighting
instructions label or the
lighting instructions located in
theinstallation and operation
manual.
1. See Service
Procedure AG-I,
Page7
2& 3. See Service
Procedure AG-II,
Page10.
1. See Service
Procedure AG-III,
Page16
Four flashes and athree
second pause.Excessivetank temperature.Thermowell sensor out of calibration.
1. See Service
Procedure AG-III,
Page16
Page4
LEDIndicator
4

Troubleshooting Chart (cont.)
For ModelsUsing Honeywell Gas Control
Five flashes and athree
second pause.Thermowell fault
Seven flashes and a
three second pause.Gas control faultdetected.
1. Damageto thermowell
wires.
2. Thermowell sensor resistance
out of range.
1. Gas control needs to be reset.
2. Gas control is wet or physically
damaged.
See Service Procedure
AG-III,Page16
Lite pilot per theinstructions
located on thelighting
instructions label or the
lighting instructions located in
theinstallation and operation
manual.
Eightflashes and athree
second pause.
Pilot flameremains on whilegas control is in
the“OFF” position.Pilot valve stuck in theopen position.
Replace gas control.
See Service Procedure
AG-III,Page18.
Page5
LED Status Control Status Probable Cause Service
Procedure
5

THERMOCOUPLE REPLACEMENT
Step 1. Turn off gas supply to water heater. Rotate knob of gas control to “OFF” position.
Step 2. Remove outer jacket door.
Step 3. Slide open inner combustion chamber door.
Step 4. Disconnect thermocouple from gas control. Locate other end of
thermocouple inside of combustion chamber and remove from pilot bracket. Pull firmly pulling away
from the pilot assembly.
Step 5. Install new thermocouple into pilot bracket making certain the thermocouple is fully engaged into the pilot
bracket. Connect other end of thermocouple to gas control (finger tight + ¼ turn).
Step 6. Route carefully through the relief opening in the combustion chamber skirt.
Step 7. To resume operation follow the instructions located on the lighting instruction label or the lighting
instructions located in the installation and operation manual.
Step 8. Slide inner door closed when finished.
SERVICE PROCEDURE AG-I
ThermocoupleTesting and Replacement
For ModelsUsing White Rodgers or
Robertshaw Gas Control
Page6
Figure 3
For White Rodgers gas
control,depress knob
slightlyand rotate
clockwise to the “OFF”
position.
For Robertshaw gas
control,rotate knob
clockwise to the “OFF”
position.
Step 1. Disconnect thermocouple from gas control.
Step 2. Using a multimeter capable of measuring millivolts, connect
one alligator clip to the end ball or contact portion of the
thermocouple, and the other alligator clip to copper portion of
the thermocouple.
Step 3. Following the lighting instruction label on the heater, proceed to light the pilot and allow to operate for
three minutes. A reading of 20 to 30 millivolts indicates good thermocouple output.
OPEN CIRCUIT THERMOCOUPLE TESTING
Figure 4
Thermocoupleposition
Figure 1
Figure 2
NOTE:
Itwill be necessary to holdthe gas control
knob down in the “PILOT” position
continuouslythroughout this test.
6

Figure 6
OPEN CIRCUIT THERMOPILE TESTING
Step 1. Disconnect red and white thermopile wires from the wire harness leading to the gas control.
Step 2. Using a multimeter capable of reading millivolts, check across thermopile leads.
Step 3. Following the instructions located on the lighting instruction label or the lighting instructions located in the
installation and operation manual, proceed to light the pilot and allow the gas control to operate for three
minutes.
Step 1. Closed circuit testing is the preferred method for testing the thermopile. Following the instructions
located on the lighting instruction label or the lighting instructions located in the installation and operation
manual, proceed to light the pilot and allow the control to operate for three minutes.
Step 2. Using a multimeter capable of measuring millivolts, measure across thermopile connections at the
gas control (see Figure 6).
CLOSEDCIRCUIT THERMOPILE TESTING
Thermopile
Connections at gas
control
Page7
Figure 5
Gas Control
Knob
SERVICE PROCEDURE AG-I
ThermocoupleTesting and Replacement
For ModelsUsing Honeywell Gas Control
NOTE:
Itmay be necessary to holdthe gas
control knob down in the “PILOT” position
continuouslythroughout this test.
NOTE:
Itmay be necessary to holdthe gas
control knob down in the “PILOT” position
continuouslythroughout this test.
InaCLOSEDCIRCUIT test:
Any reading over 300 millivolts
indicates good thermopileoutput.
For readingsunder 300 millivolts
replacement of thermopileis
recommended.
Inan OPEN CIRCUIT test:
Any reading over 400 millivolts
indicates good thermopileoutput.
For readingsunder 400 millivolts
replacement of thermopileis
recommended.
7

Figure 7
SERVICE PROCEDURE AG-I
ThermopileTesting andReplacement
ForModelsUsing Honeywell Gas Control
Step 1. Turn off the gas supply to the water heater by rotating the gas control knob to the “OFF” position
(see Figure 7).
Step 2. Remove outer jacket door.
Step 3. Remove or slide open the inner combustion chamber door.
Step 4. Disconnect red and white thermopile wires from the wire harness leading
to the gas control.
Step 5. Disconnect the thermopile from the pilot bracket using a 7/16” open-end wrench.
Step 6. Install the new thermopile into the pilot bracket and tighten the threads using care not to damage the
thermopile lead wires. Route new wires through the appropriate opening in the combustion chamber.
Step 7. Reconnect the lead wires being careful to match the colors (red to red and white to white).
Step 8. Reinstall, or slide closed, inner combustion chamber door.
Step 9. Replace the outer door.
Step 10. To resume operation follow the instructions located on the lighting instruction label or the lighting
instructions located in the installation and operation manual.
Page8
THERMOPILE REPLACEMENT
Gas Control Knob
(ShowninOFF
position)
8

PILOT ASSEMBLY INSPECTION,
CLEANING ANDREPLACEMENT
Step 1. Turn off gas supply to water heater. Rotate knob
of gas control to “OFF” position.
Step 2. Remove outer jacket door.
Step 3. Slide open inner combustion chamber door.
Step 4. Disconnect thermocouple, pilot tube,
and feedline from gas control.
NOTE: Feedline nut for natural gas control
uses right hand threads, LP control uses left hand thread.
Step 5. Remove burner assembly from combustion chamber.
Step 6. Remove pilot assembly from feedline.
Step 7. Inspect pilot for the following:
a) Primary air openings for blockage. Must be free from any
debris (dirt, lint, etc).
b) Kinks or cracks in the pilot tube. If found,
the pilot must be replaced.
Step 8. Inspect pilot orifice:
a) Remove ½" nut from bottom of pilot assembly.
b) Remove pilot tube and pilot orifice.
c) inspect pilot orifice for blockage, must be cleaned or replaced.
SERVICE PROCEDURE AG-II
Pilot AssemblyInspection,Cleaning
andReplacement ForModelsUsing White
RodgersorRobertshawGas Control
Step 9. Install pilot assembly to feedline, secure with screw from step 6.
Step 10. Re-Install burner assembly into combustion chamber, connect feedline, pilot tube and thermocouple
to gas control.
Step 11. Slide inner combustion chamber door closed and re-attach outer jacket door.
Step 12. To resume operation follow the instructions located on the lighting instruction label or the lighting
instructions located in the installation and operation manual.
Page9
Primary Air
Opening
R
ForWhiteRodgersgas
control,depress knob
slightlyandrotate
clockwiseto the“OFF”
position.
ForRobertshawgas
control,rotateknob
clockwiseto the“OFF”
position.
Pilot Orifice
FeedlineNut
Figure 8
Figure 9
Figure 10
Figure 11
9

SERVICE PROCEDURE AG-II
Pilot AssemblyInspection, Cleaning
and Replacement For ModelsUsing
Honeywell Gas Control
R
Step 1. Turn off the gas supply to the water
Heater. Rotate gas control knob to the
“OFF” position.
Step 2. Remove outer jacket door.
Step 3. Remove burner assembly per
Service Procedure AG-IV page 20.
Step 4. Remove the pilot assembly from the burner assembly.
Step 5. Inspect the pilot assembly for the following:
a)Primary air opening for any blockage .
Must be free from any debris (dirt, lint, dust, etc.).
b) Kinks or cracks in the pilot tube. If found, the pilot
must be replaced.
Step 6. Inspect pilot orifice:
a) Remove 7/16” nut from the bottom of the pilot assembly.
b) Remove pilot tube and pilot orifice.
c) Inspect pilot orifice for blockage, must be free from any debris (dirt, lint, dust, etc.).
d) Reassemble pilot orifice and pilot tube to pilot assembly.
Step 7. Install pilot assembly to burner assembly using the screw from Step 4.
Step 8. Reinstall burner assembly per Service Procedure AG-IV page 22: Steps 10 through 12.
Step 9. To resume operation follow the instructions located on the lighting instruction label or the lighting
instructions located in the installation and operation manual.
Step 10. Check all gas connections for gas leaks using a soapy water solution.
PILOT ASSEMBLY INSPECTION,
CLEANING ANDREPLACEMENT
Figure 12
Figure 13
Primary Air
Opening
Pilot Orifice
Page10
10

Figure 14
SERVICE PROCEDURE AG-II
Pilot AssemblyInspection, Cleaning
and Replacement For ModelsUsing
Honeywell Gas Control
R
IGNITER/ELECTRODE TESTING AND
REPLACEMENT
With the pilot not in operation (no pilot flame) the igniter and electrode circuit function can be observed by
opening the combustion chamber door and viewing whether there is a sparking action.
Step 1. Make sure the gas control is in the “OFF” position.
Step 2. Remove outer jacket door.
Step 3. Slide open or remove the inner
combustion chamber door.
Step 4. Depress the igniter button repeatedly while viewing
the spark through the open door of the combustion
chamber. If there is no spark proceed to Step 5.
If there is a spark, the igniter is OK.
Step 5. Remove the lead wire from the igniter at the connector
provided for this. Hold the igniter lead from the gas valve
close to an unpainted metal surface (such as the burner feedline)
and depress the igniter button (see Figure 15). If there is a spark the igniter is OK.
If no spark is present the igniter is not functioning and the gas control
must be replaced per Service Procedure AG-III page 18.
RepeatedlyDepress
Igniter
Figure 15
Look for spark in
thegap
Page11
11

SERVICE PROCEDURE AG-III
Gas Control Testing and Replacement
For Modelsusing White Rodgers or
Robertshaw Gas Control
The gas control is a non repairable device. If trouble shooting has determined a problem with the gas control, it must be
replaced.
If the burner and/or pilot do not function, service checks for gas pressure, thermocouple output, magnet assembly and
ECO are to be performed. If these check OK, the gas control may be faulty.
MANIFOLDPRESSURE TESTING (this procedure assumes amaximumline pressure of14.0" w.c.)
Step 1. Set gas control to “OFF” position.
Step 2. Remove pressure tap plug and install
pressure tap.
Step 3. Connect manometer to pressure tap.
Step 4. Follow lighting instructions and proceed to light
main burner and observe manometer reading.
Step 5. Proper operating range for natural gas is 4.0 ±0.3" W.C.
Proper operating range for L.P. gas is 10.0 ±0.5" W.C.
Step 6. If pressure is OK, set gas control to “OFF”
remove manometer and pressure tap and replace pressure tap plug. Check for gas leaks before placing water
heater back in operation. If pressure is out of the specification noted in step 5, proceed to step 7 or 8 for proper
service procedure.
Step 7. For White Rodgers control, the manifold pressure is not adjustable. If manifold pressure is outside the range
in step 5, the control must be replaced.
Step 8. For Robertshaw control, the manifold pressure is adjustable, proceed to step 9 for adjustment procedure
Step 9. While burner is in operation, remove regulator access cap to expose the regulator adjusting screw. With small
screw driver, rotate adjusting screw clockwise to increase pressure and counter clockwise to decrease pressure.
Step 10. Replace regulator access cap, set gas control to “OFF”. Remove manometer and
pressure tap and replace pressure tap plug. Check for gas leaks before placing water heater back in operation.
LINE PRESSURE
The gas control is designed for a maximum line pressure of 14.0" w.c. and a minimum line pressure of 1.0"w.c. over the
water heater rated manifold pressure. Line pressure must be checked with burner on and burner off to assure proper
readings.
Page12
Pressure Tap
Shown
Installed
Gas Control Testing and Replacement
Figure 16
Figure 17
Figure 18 Figure 19
12

See SERVICE PROCEDURE AG-II
THERMOCOUPLE TESTING
MAGNET ASSEMBLY TESTING (White Rodgers Control)
Page13
Step 1. Following the lighting instruction label on the heater, proceed to light the pilot and allow to operate for
three minutes. If the pilot will not stay lit, hold the pilot button (located on the combination
thermostat/gas valve) down during this test
Step 2. Using a multimeter capable of measuring millivolts, connect one lead
using an alligator clip to the copper sheath of the thermocouple, use the second lead of the multi meter to
probe the top terminal located at the back of the gas control.
Step 6. With a meter reading of 13 millivolts or greater, rotate knob of gas control to the
“OFF” position.
Step 7. The magnet should remain closed for a drop of at least 6 millivolts. You will here a “snap” or “click” sound
when the magnet opens, if you hear this sound prior to a drop of 6 millivolts, the magnet is out of
specification and the gas control should be replaced.
MAGNET ASSEMBLY TESTING (Robertshaw Control)
Step 1. Disconnect thermocouple from gas control.
Step 2. Connect a thermocouple adaptor
(BWC P/N 239-44642-00, Robertshaw P/N 75036) at the
thermocouple location in the gas control.
Step 3. Reconnect thermocouple to adaptor. Make certain all connections
are tight (finger tight plus ¼” turn).
Step 4. Using a multimeter capable of measuring millivolts, connect one
alligator clip to the set screw of the adaptor and the other alligator
clip to copper portion of the thermocouple.
Step 5. Following the lighting instruction label on the heater, proceed to light the pilot and allow to operate for
three minuets.
Step 6. With a meter reading of 13 millivolts or greater, rotate knob of gas control to the
“OFF” position.
Step 7. The magnet should remain closed for a drop of at least 6 millivolts. You will here a “snap” or “click” sound
when the magnet opens, if you hear this sound prior to a drop of 6 millivolts, the magnet is out of
specification and the gas control should be replaced.
Figure 21
Figure 22
Figure 20
Probetop terminal on backof
gascontrol
Alligatorclipto copper sheath
ofthermocouple
SERVICE PROCEDURE AG-III
GasControl Testing andReplacement
ForModelsusing WhiteRodgersor
Robertshaw GasControl
13

GAS CONTROL REPLACEMENT
Step 1. Rotate knob of the gas control
to the “OFF” position.
Step 2. Turn off gas supply to water heater.
Step 3. Disconnect gas supply line from
gas control.
Step 4. Turn off water supply and drain water heater completely.
Step 5. Remove outer jacket burner access door.
Step 6. Slide open inner combustion chamber door.
Page14
ForWhite Rodgers gas
control,depress knob
slightlyand rotate
clockwise to the “OFF”
position.
For Robertshaw gas
control,rotate knob
clockwise to the “OFF”
position.
Step 1. Disconnect thermocouple from gas control.
Step 2. Using a multimeter capable of measuring Ohms (or continuity),
attach one lead (alligator clip) to the pilot tube. Insert the other lead
(probe) fully into the magnet opening, Be sure the probe makes
contact only at the top center of the magnet opening. Do not allow
the probe to make contact with the threaded sides of the opening.
Step 3. If continuity is indicated, the ECO is OK. If continuity is not indicated, the ECO has opened and the
gas control must be replaced.
ECO (EnergyCut Off) TESTING
SERVICE PROCEDURE AG-III
Gas Control Testing and Replacement
For Modelsusing White Rodgers or
Robertshaw Gas Control
Figure 23
Figure 24
Figure 25
Figure 26
14

Step 7. Removal of gas control.
a) Disconnect main burner feedline, pilot tube and thermocouple
from gas control & remove burner from combustion chamber.
NOTE: Feed line nut for natural gas control uses right hand threads,
LP control uses left hand thread.
b) Remove gas control from heater,
rotating counter clockwise using a control body wrench or a
length of ½" NPT pipe threaded into inlet of control.
Step 8. Installation of gas control.
a) Install new gas control using a control body wrench or a length of ½" NPT
pipe threaded into inlet of control. DO NOTOVER TIGHTEN.Use caution not to damage cast
aluminum body of gas control. Be certain not to damage the bundled wire
leads.
NOTE: gas control must be installed in proper upright position to
assure the feedline will align properly at the inner door flange.
DO NOT OVER TIGHTEN. If control is turned past proper alignment, do not
reverse direction to align.
b) Reattach main burner feedline, pilot tube and thermocouple to gas control.
NOTE: Feedline nut for natural gas control uses right hand threads,
LP control uses left hand thread.
c) Connect gas supply piping to inlet of control. Use back up wrench on wrench boss of control, never
use back up wrench on body of control.
Page15
To remove or install control,insert only
½" NPTthreaded pipe into inlet and
use to loosen or tighten control.
Wrench Boss
Step 9. Reconnect gas supply to gas control.
Step 10. Resume water supply to water heater. Be sure tank is full of water.
Step 11. Slide inner combustion chamber door closed
Step 12. Re-attach outer jacket door.
Step 13. To resume operation follow the instructions located on the lighting instruction label or the lighting instructions
located in the installation and operation manual.
SERVICE PROCEDURE AG-III
Gas Control Testing and Replacement
For Modelsusing White Rodgers or
RobertshawGas Control
Figure 27
15

SERVICE PROCEDURE AG-III
Honeywell Thermowell Testing and
Replacemet
Step 1. If gas control has gone into lockout due to excessive tank temperature (four flashes and a three second
pause) reset the gas control to the “OFF” position. Then follow the instructions located on the lighting
instruction label or the lighting instructions located in the installation and operation manual.
Step 2. Observe the water heater operation. If the gas control continues to lockout due to excessive tank
temperature proceed to Step 3, thermowell testing, to determine the cause.
Step 3. To perform thermowell testing turn the gas control to the “OFF” position and disconnect the
thermowell harness from the gas control.
Step 4. Using a multimeter set to measure Ohms determine the resistance of the thermowell sensor (See
caution on this page).
Step 5. Hold one probe in the center pin and measure the outside positions pins (see figure 29 & 30).
Step 6. Refer to Table 1 on page 17 to determine the correct resistance value for the water heater tank
temperature.
Step 7. If the resistance values are correct the gas control needs to be replaced. If they are incorrect the
thermowell needs to be replaced.
Figure28Figure29
Figure30
CAUTION
DO NOTUse standard multimeter probes to
test. Doing so will damage connector. Use
special pintype electronicprobes or small
diameter wire pins inserted into connector
Disconnect
thermowell wire
harness
Page16
HONEYWELL THERMOWELL TESTING
16

WARNING
Stored water may be HOT when
performingthe followingsteps in this
procedure. Take necessary precaution to
prevent personal injury
SERVICE PROCEDURE AG-III
Honeywell Thermowell Testing and
Replacement
DETERMINE WATERHEATERTANK TEMPERATURE
NOTE:
Itis important to understand oncetheresistance
for thethermowell is determined, waterflow
throughthewaterheatershouldnot occur. Prior
to performing thesteps below turn off coldwater
supplyto thewaterheater. This will prevent cold
waterflow into thetankaffecting theresistance
value ofthethermowell.
Step 1. Turn the gas control to the “OFF” position and
disconnect the thermowell harness from the gas control.
Step 2. Using a multimeter set to measure Ohms determine the resistance of the thermowell sensor (See
caution on this page).
Step 3. Hold one probe in the center pin and measure the outside positions pins (see figure 29 & 30, page 16).
Step 4. Draw approximately 1 quart of water from the drain valve and immediately measure the water
temperature using an accurate thermometer. It may be necessary to open a hot water faucet to allow
the heater to drain.
Step 5. Refer to Table 1 below to determine the correct resistance value for the water heater tank temperature.
Example: If the temperature of the water is 84°F, then the resistance through the sensor would be 8449 (see
shaded area). NOTE: Sensor resistance increases as the temperature falls.
°F 012345678 9
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 1000 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 1953 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 F
Page17
Sensor Resistance at Various Temperatures
(Table 1)
CAUTION
DO NOT use standard multimeter
probes to test. Doingso will damage
connector. Use special pin type
electronic probes or small diameter
wire pins inserted into connector
17

SERVICE PROCEDURE AG-III
Honeywell Gas Control and Thermowell
Replacement
Figure 31
Step 1. Turn the gas control knob to the “OFF” position.
Step 2. Turn off water supply and drain water heater completely.
Step 3. Turn off and disconnect gas supply to control
Step 4. Disconnect wire harness and burner
assembly from the gas control.
Step 5. Remove gas control and thermowell by rotating flats of the thermowell counter clockwise.
HONEYWELL GAS CONTROL & THERMOWELL REMOVAL
HONEYWELL GAS CONTROL REMOVAL FROM THERMOWELL
NOTE; Following the instructions below allows the removal of the gas control from the thermowell without
removing the thermowell from the tank.
Step 1. Turn the gas control knob to the “OFF” position.
Step 2. Turn off and disconnect gas supply piping to the gas control.
Step 3. Disconnect wire harnesses and burner assembly from the gas control.
Step 4. Using the gas control service tool (part number 239-45991-00) available from your Bradford White
parts supplier, insert tool into the back of the gas control (see Figure 32 & 33).
Step 5. Pivot service tool towards water heater as far as possible (see Figure 34). Lift up straight on gas
control. The gas control should move about 1/8”. Hold gas control in position and remove tool.
Lift straight up on the gas control to remove completely from the thermowell.
Figure 32 Figure 33
Insert tool into
backofgas
control
View from backof
gas control for clarity
Figure 34Page18
Gas Control
Thermowell
18

SERVICE PROCEDURE AG-III
Honeywell Gas Control and Thermowell
Replacement
HONEYWELL GAS CONTROL ASSEMBLY TO THERMALWELL
Step 1. Install threaded end of thermowell into water heater. When tight, be sure thermowell flange is
positioned so that thermowell relief opening is in the 6 o’clock position for proper control alignment
(see Figure 35).
Figure 35
Thermowell
flangeslots
Route wire through
reliefopening
Step 2. Route lead wires through the relief opening (see Figure 35).
Step 3. Align slots located on the thermowell flange with tabs located on the back of the gas control
(see Figure 36).
Figure 36
Gas control tabs
Step 4. Carefully push the gas control back onto the thermowell flange.
Step 5. Install burner assembly and reconnect pilot tubing and main burner feed line to gas control.
Step 6. Reconnect wire harness and igniter wire to the gas control.
Step 7. Resume water supply to water heater and check for leaks. Be sure tank is full of water.
Step 8. Reconnect the gas supply to gas control. Check for gas leaks using a soapy water solution.
Step 9. To resume operation follow the instructions located on the lighting instruction label or the lighting
instructions located in the installation and operation manual.
Page19
6o’clockposition
19

Step 1. With main burner in operation slide the inner combustion chamber door open.
Step 2. To adjust for proper burning, loosen the air shutter nut, rotate the shutter to close the opening in the burner,
then slowly rotate the shutter until the yellow tips are minimized and the flame becomes blue. Tighten the air
shutter nut. Too much air will cause the flame to lift off the burner ports and create noisy burner operation.
Too little air (yellow tips) will result in soot formation.
At periodic intervals (not more then 6 months) a visual inspection should be made of the main burner for proper operation
and to insure no debris accumulating.
Main burner should light smoothly from pilot and burn with a blue flame with a minimum of yellow tips.
Steel burner models have a self adjusting air mixture and do not have an adjustable air shutter. Cast iron burner can have
the gas and air mixture properly proportioned by adjusting the air shutter on the mixer face of the main burner (see step 2
below).
Main burner must be free from any debris accumulation that may effect burner operation (see burner cleaning procedure
on page 21).
MAIN BURNER: Inspection, Adjustment, Cleaning and Replacement
CAST IRON BURNER ADJUSTMENT
SERVICE PROCEDURE AG-IV
Burner Operation Inspection, Adjustment
Cleaning and Replacement
WARNING
Inner door and burner components may be HOT when performing this operation. Take
necessary precaution to prevent personal injury.
Air Shutter
Nut
Page20
R
Figure 37
20