Bradford White MI30T Series User manual

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Manual 238-44943-00D
SERVICE
MANUAL
Troubleshooting Guide
and Instructions for Service
FEATURING
(To be performed ONLY by
qualified service providers)
For the Bradford White
Defender Safety System®
Models:
MI30T*F(BN,CX,SX)
MI30S*F(BN, CX,SX)
MI303T*F(BN,CX,SX)
MI40T*F(BN,CX,SX)
MI403S*F(BN,CX,SX)
MI404T*F(BN,CX,SX)
MI503*F(BN,CX,SX)
MI50L*F(BN,CX,SX)
MI504S*F(BN,CX,SX)
MI60T*F(BN,CX,SX)
C(S,D)W2504T*F(BN,CX,SX)
M430T*F(BN,CX,SX)
M440T*F(BN, CX,SX)
M4403S*F(BN,CX,SX)
M4503*F(BN,CX,SX)
M460T*F(BN,CX,SX)
M1XR403S*F(BN,CX,SX)
M1XR504T*F(BN,CX,SX)
M2XR504T*F(BN,CX,SX)
M2XR65T*F(BN,CX,SX)
M2C504T*F(BN,CX,SX)
50T65F(B*N,C*X,S*X)
65T65F(B*N,C*X,S*X)
(*) Denotes Warranty Years
Gas Water Heaters
Flammable Vapor Ignition
Resistant Water Heaters
http://waterheatertimer.org/How-to-install-gas-water-heater.html#troubleshoot

The Bradford White
DEFENDER
Safety System®
Flammable Vapor Ignition Resistant Water Heaters
Table of Contents
Page Service Procedure
Introduction 3 - - -
Trouble shooting Chart 4 - - -
Inner Door Gasket Removal, Inspection, Replacement and Installation 7 RG-I
Thermocouple/Thermopile Testing and Replacement 10 RG-II
Pilot Assembly Inspection Cleaning and Replacement 13 RG-III
Piezo Igniter, Electrode Testing and Replacement 14 RG-IV
White Rodgers/Robertshaw Gas Valve Testing and Replacement 15 RG-V
Honeywell Gas Control Testing, Disassembly, and Replacement 20 RG-VI
Burner Operation Inspection, Adjustment, Cleaning and Replacement 31 RG-VII
Resettable Thermal Switch Testing and Replacement 34 RG-VIII
ScreenLok®Flame Arrestor Cleaning 36 RG-IV
Dip Tube and Anode Inspection and Replacement 37 RG-X
Generic Parts List 39 - - -
2
2
2

The Bradford White DEFENDER Safety System®
The Bradford White DEFENDER Safety System®was designed to resist
the ignition of flammable vapors that can occur outside of the water
heater. Use and installation are nearly identical to previous versions of
atmospherically fired and vented water heaters. A number of exclusive
design features are incorporated in the system that will require additional
knowledge on the part of the qualified service provider. The following
information will instruct service professionals on the function, proper
diagnosis and repair of water heaters employing the Bradford White
DEFENDER Safety System.
How the Safety System Works
During normal operation, air for combustion is drawn into the water
heater through the opening in the jacket. This air travels down and around
the combustion chamber and enters through holes in the very bottom of
the corrosion-resistant combustion chamber. The air then travels up
through the oriented flame arrestor plate louvers, where the velocity of the
air is increased and its direction altered. The air then mixes in a normal
manner with the supplied gas and is efficiently combusted, producing very
low NOx emissions.
In the case where trace amounts of flammable vapors are present in the air
flowing into the combustion chamber, the vapors are harmlessly ignited
by the burner / pilot flame. If flammable vapors are in sufficient quantity
to prevent normal combustion, the burner/pilot flame is shut down.
Should the flammable vapors continue to the burner, the flame arrestor
plate prevents the flames from traveling backwards and igniting vapors
outside of the combustion chamber. The calibrated, multipurpose thermal
switch recognizes this and shuts down the pilot and main burner. This
switch also deactivates the burner and pilot in the unlikely event of
restricted airflow caused by severe lint, dust or oil accumulation on the
arrestor plate.
INTRODUCTION
3
3
3

White Rodgers/Robertshaw Gas Valve Troubleshooting Chart
SYMPTOM PROBABLE CAUSE CORRECTIVE ACTION
Pilot Will Not Light
1. No incoming gas or too low gas
pressure.
2. Gas control knob set to wrong position.
3. Pilot light button not being fully
depressed when attempting to light pilot.
4. Pilot orifice or pilot tube is obstructed or
kinked.
5. Pilot electrode not sparking to pilot.
6. Piezo igniter not functioning.
1. Poor thermocouple connection at
combination thermostat/gas valve.
2. Thermocouple not fully engaged in pilot
assembly bracket.
3. Pilot flame is not fully enveloping the
thermocouple “hot” junction.
4. Weak or defective thermocouple.
5. Open ECO on combination thermostat/
gas valve.
6. Defective magnet in combination
thermostat/gas valve.
7 Resettable thermal switch has opened.
Pilot Will Not
stay lit
when button is
released
Pilot will light but
the main burner
will not come on
1. Combination thermostat/gas valve set too
low for desired water temperature.
2. Combination thermostat/gas valve
temperature is satisfied.
3. Insufficient gas supply or low gas
pressure.
4. Combination thermostat/gas valve has
wide differential or is out of calibration.
Pilot goes out
periodically (after
heating cycles,
once a day, once
a week 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. Combination thermostat/gas valve set too
low for desired water temperature.
2. Cold inlet water temperature is very cold.
3. High demand periods.
4. Incorrectly sized water heater for
application.
5. Combination thermostat/gas valve is out
of calibration/not functioning.
6. Out of spec dip tube is diluting hot water
with cold water.
1. Turn on gas supply and/or check line
pressure.
2. Review lighting instruction. Set
combination/thermostat
gas valve to correct position.
3. Review lighting instruction. Fully depress
pilot lighting button.
4. Clean, repair or replace.
5. Verify correct electrode position. Replace
pilot assembly.
6. Replace Piezo igniter.
1. Check connection at combination
thermostat/gas valve. Proper tightness
should be finger tight plus ¼ turn.
2. Inspect thermocouple to ensure that it is
fully engaged into pilot bracket.
3. Adjust tip of thermocouple to be fully
engulfed by pilot flame.
4. Check thermocouple and replace if
necessary.
5. Check ECO continuity and replace
combination thermostat/gas valve if
necessary.
6. Check magnet operation and replace
combination thermostat/gas valve if
necessary.
7. Determine cause of switch activation. To
reset, depress button on resettable thermal
switch located on inner door.
1. Adjust temperature dial on combination
thermostat/gas valve.
2. Check temperature dial setting on
combination thermostat/gas valve.
3. Check gas supply and line pressure.
4. Check combination thermostat/gas valve
for proper operation, replace if
necessary.
1. Verify adequate combustion air is available
to the unit. Check and clear Jacket slot
openings of any dirt, dust, restrictions or
other obstructions. Inspect flame arrestor
plate and clean with stiff bristled brush
and/or vacuum to remove any debris
accumulation.
2. Check venting for proper sizing and proper
operation
3. Check gas supply and line pressure.
1. Check dial on combination thermostat/gas
valve.
2.Extremely cold water going into the heater
will decrease the amount of hot water
produced. It may be necessary to temper
incoming water supply.
3. Adjust high demand usage.
4. Contact Plumbing professional.
5. Check combination thermostat/gas valve
for proper operation, replace if
necessary.
6. Inspect dip tube and replace if necessary.
SERVICE
PROCEDURE
1. See Service Procedure
RG-V, Page 12.
4. See Service Procedure
RG-III, Page 10.
5. See Service Procedure
RG-III, Page 10.
6. See Service Procedure
RG-IV, Page 11.
4. See Service Procedure
RG-II, Page 8
5. See Service Procedure
RG-V, Page 14
6. See Service Procedure
RG-V, Page 13
2. See Installation &
operation manual.
3. See Service Procedure
RG-V, Page 12
4. See Service Procedure
RG-V, Page 12
1. See Service Procedure
RG-VIII, Page 22
3. See Service Procedure
RG-V, Page 12
5. See Service Procedure
RG-V, Page 12
6. See Service Procedure
RG-IX, Page 23
Flammable Vapor Ignition Resistant Water Heaters
4
4
4

Honeywell Gas Control Troubleshooting Chart
LED Status Control Status Probable Cause
None (LED not on
or flashing
Gas Control is operating normally.
Pilot flame may not be present.
Check for pilot flame through sight
glass and light if necessary.
If set point knob is in “PILOT”
position then pilot flame is
detected. Turn set point knob to
desired setting.
One flash and
three second
pause
LED on
continuously
(Solid)
Set point knob has been recently
turned to the “OFF” position. Wait
until LED goes out before
attempting to relight
Two flashes and
three second
pause
Weak pilot signal detected. System
will reset when pilot flame is
sufficient.
1. Gas Control is functioning
normally.
2. Gas Control is not powered. Light
pilot.
3. Thermopile failure.
Gas Control is powered and waiting
for the set point knob to be turned to
a water temperature setting.
Set point knob was turned to “OFF”
position.
1. Thermopile failure
2. Unstable pilot
3. Pilot tube block or restricted.
4. Resettable thermal switch has
opened
Service
Procedure
If the pilot will not stay
lit replace pilot
assembly. If problem
persists replace Gas
Control.
Normal operation.
Adjust thermostat to
desired temperature
setting.
LED will go out and the
control will function
normally when the pilot
is lit.
1. See service
procedure RG-II
2. See service
procedure RG-III
3. See service
procedure RG-III
4. See service
procedure RG-VIII
Flammable Vapor Ignition Resistant Water Heaters
Green LED Indicator
Observe green 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.
Three flashes and
three second
pause
Insufficient water heating. System
will reset.
1. Temperature sensor out of
calibration
1. See service
procedure RG-VI
Four flashes and
three second
pause
Excessive tank temperature.
System must be reset.
1. Temperature sensor out of
calibration
2. Faulty Gas Control
1. See service
procedure RG-VI
2. See service
procedure RG-VI
5
5
5

Honeywell Gas Control Troubleshooting Chart
LED Status Control Status Probable Cause
Five flashes and
three second
pause
Thermostat/well sensor fault.
Gas Control electronic fault
detected.
Seven flashes and
three second
pause
Eight flashes and
three second
pause
Standing pilot remains on while set
point knob is in “OFF” position.
1. Damage to the temperature
sensor.
2. Temperature sensor resistance
out of range.
1. Control need to be reset.
2. Control is wet or physically
damaged.
Pilot valve stuck in open position.
Service
Procedure
1. See service
procedure RG-VI
1. Reset Gas Control
2. Replace Gas
Control.
Replace Gas Control.
Flammable Vapor Ignition Resistant Water Heaters
Green LED Indicator
Observe green 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.
6
Water leak detected by accessory
module.
Six flashes and
three second
pause
Excessive amount of water in drain
pan/water dam.
1. Check T&P valve
2. Check all water
fittings.
3. Pressurize and leak
test tank.
6
6

Inner Door Removal Procedure
Step 1. Rotate knob of the combination
thermostat/gas valve to the “OFF” position.
Step 2. Remove outer jacket burner access door
Step 3. Inner Door Removal.
a) Disconnect resettable thermal switch wire leads (leading from Gas Control/gas valve).
b) Remove (2) hex drive screws from right side inner door.
c) Remove (2) hex drive screws from flange section of inner door.
d) Remove (2) hex drive screws from left side inner door.
e) Remove inner door and inspect per step 4.
Step 4. Fully inspect inner door gaskets for the following:
>Tears >Other imperfections that will inhibit proper seal
>Missing Material >Gasket adhesion to inner door
>Cracks >Material left on combustion chamber (around opening)
>Dirt or debris
If the gasket is not effected by any of the above, gasket replacement is not required. If replacement is required,
proceed to Inner Door Gasket Replacement Procedure.
Inner Door Gasket Replacement Procedure.
WARNING
If the information in these instructions is not
followed exactly, a fire or explosion may result causing
property damage, personal injury or death.
Step 5. After inspection of inner door as noted in step 4, completely remove gasket and adhesive residue from right
and left side inner doors as needed.
Step 6. Use RTV sealant (recommended bead size 1/8") to secure the inner door gasket to the inner door sections
(right & left). Refer to illustration on next page for proper application. Note the overlap configuration in the
flange area of the inner door. Set the flange section first, this will help to achieve the proper over lap position.
For Robertshaw Control,
rotate knob clockwise to
the “OFF” position.
The Bradford White
DEFENDER
Safety System®
For White Rodgers Control,
depress knob slightly and rotate
clockwise to the “OFF” position.
For Honeywell Control, rotate
knob counter-clockwise to the
“OFF” position.
SERVICE PROCEDURE RG-I
Inner Door/Gasket Removal, Inspection
Replacement and Reinstallation
Resettable Thermal Switch
Wire Connection
Hex Drive Screws
Right and Left Side Inner Door.
Hex Drive Screws at
Flange Area of Inner Door
7
7
7

Installation of Inner Door With Gasket.
WARNING
Stripped fastener connections may allow
for seal breach of inner door. A seal
breach may result in a fire or explosion
causing property damage, personal injury
or death. Do not over tighten screws in
steps 8, 10 and 11.
If a fastener connection is stripped,
contact the manufacturer listed on the
water heater rating plate.
Step 7. Clean any residual gasket residue or other debris
from combustion chamber surface before
installing the inner door/gasket assembly.
Step 8. Place the left side inner door into position first.
Firmly position the radiused channel of the inner
door around the feedline. Using the (2) hex drive
screws from step 3d, secure left side inner door in
place. DO NOT OVER TIGHTEN SCREWS.
Step 9 Position thermocouple, pilot tube and Piezo wire
against left side inner door flange gasket.
DO NOT ROUTE THROUGH RADIUSED
CHANNEL WITH FEEDLINE.
Radiused Channel for
Feedline
Position thermocouple/thermopile,
pilot tube and piezo wire.
PLACE FLANGE
SECTIONS FIRST
RECOMMENDED PATTERN
FOR RTV SEALANT
GASKET
OVERLAP MUST
BE AS SHOWN
±1/32" ENLARGED
VIEW OF
FLANGE AREA
EXPANDED VIEW
VIEW WITH GASKETS
IN PLACE
SERVICE PROCEDURE RG-I
Inner Door/Gasket Removal, Inspection
Replacement and Reinstallation
8
8
8

Step 10. Firmly place right side inner door flange against the left side inner door flange and secure with (2) hex drive
screws from step 3c. DO NOT OVER TIGHTEN SCREWS.
Step 11. Align right side inner door to combustion chamber and verify the fastener holes of the combustion
chamber are aligned with the right side inner door slotted opening. Verify seal integrity around combustion
opening. Secure right side inner door using (2) hex drive screws from step 3b. DO NOT OVER TIGHTEN
SCREWS. Verify both left and right sides of the inner door are properly positioned and sealed against
the combustion chamber.
Step 12. Reconnect lead wires from combination thermostat/gas valve to resettable thermal switch (See photo in step
3). Note, wire terminations are interchangeable with either resettable thermal switch connections.
Step 13. Replace outer jacket burner access door.
Step 14. To resume operation follow the instructions located on the lighting instruction label or the lighting instructions
located in the installation and operation manual.
Verify threaded hole
alignment with slotted
openings in inner door.
Secure flange with
hex drive screws.
SERVICE PROCEDURE RG-I
Inner Door/Gasket Removal, Inspection
Replacement and Reinstallation
9
9
9

Step 1. Closed circuit testing is the preferred method for testing thermocouple. Following the lighting instruction
label on the heater, proceed to light the pilot and allow to operate for three minuets. 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 combination thermostat/gas valve.
Step 3. If meter reads 10 millivolts or higher, the thermocouple is OK. If reading is below 10 millivolts,
replace the thermocouple.
CLOSED CIRCUIT THERMOCOUPLE TESTING (White Rodgers Control)
The Bradford White
DEFENDER
Safety System®
Probe top terminal on
back of combination
thermostat/gas valve Alligator clip to copper
sheath of thermocouple
Step 1. Disconnect thermocouple from combination thermostat/gas valve.
Step 2. Connect a thermocouple adaptor
(BWC P/N 239-44642-00, Robertshaw P/N 75036) at the
thermocouple location in the combination thermostat/gas valve.
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. If the pilot will not stay lit, hold the red reset button (located on the combination
thermostat/gas valve) down during this test
Step 6. If meter reads 13 millivolts or higher, the thermocouple is OK. If reading is below 13 millivolts
replace the thermocouple.
CLOSED CIRCUIT THERMOCOUPLE TESTING (Robertshaw Control)
SERVICE PROCEDURE RG-II
Thermocouple/Thermopile Testing and
Replacement
10
10
10

THERMOCOUPLE REPLACEMENT (White Rodgers/Robertshaw Gas Valve)
Step 1. Turn off gas supply to water heater. Rotate knob of combination
thermostat/gas valve to “OFF” position.
Step 2. Remove outer jacket door.
Step 3. Remove right side of inner door per SERVICE PROCEDURE RG-I, steps 3a through 3c.
Step 4 Disconnect thermocouple from combination thermostat/gas valve. 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. Position thermocouple against left side inner door flange at its original position. Connect other end of
thermocouple to combination thermostat/gas valve (finger tight + ¼ turn).
Step 6. Inspect inner door gasket per
SERVICE PROCEDURE RG-I, Step 4.
Step 7. Install right side inner door per
SERVICE PROCEDURE RG-I,
Step 10 through Step 13
Step 8. To resume operation follow the instructions located on the lighting instruction label or the lighting
instructions located in the installation and operation manual.
Thermocouple position
For White Rodgers Control,
depress knob slightly and rotate
clockwise to the “OFF” position.
For Robertshaw Control, rotate
knob clockwise to the “OFF”
position.
Step 1. Disconnect thermocouple from combination thermostat/gas valve.
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. It will be necessary to hold the pilot button down continuously throughout this test.
A reading of 20 to 30 millivolts indicates good thermocouple output.
OPEN CIRCUIT THERMOCOUPLE TESTING (White Rodgers/Robertshaw Gas Valve)
SERVICE PROCEDURE RG-II
Thermocouple/Thermopile Testing and
Replacement
11
11
11

The following test should be performed while the pilot flame is on.
Step 1. Turn knob to pilot position and depress.
Step 2. Continue pressing knob and remove red (+) wire from resettable thermal door switch.
Step 3. Using a multimeter capable of measuring millivolts, connect the positive side of the multimeter to the
terminal of the resettable thermal door switch. Connect the negative side of the multimeter to any earth
ground location (jacket base, screw, etc.).
OPEN CIRCUIT THERMOPILE TESTING (Honeywell Gas Control)
Normal thermopile operation will be between 350mV - 850mV. If reading is less than 350mV, replacement of pilot
assembly is recommended following SERVICE PROCEDURE RG-III.
Step 4. If thermopile reading is between 350mV - 850mV, remove multimeter and reconnect red wire to positive (+)
terminal of Gas Control.
Step 5. Release Gas Control knob and turn to desired setting to resume normal operation.
SERVICE PROCEDURE RG-II
Thermocouple/Thermopile Testing and
Replacement
Resettable Thermal Door
Switch Terminal (+)
Jacket Base Screw (-)
12
12
12

PILOT/ELECTRODE ASSEMBLY INSPECTION,
CLEANING AND REPLACEMENT
Step 1. Turn off gas supply to water heater. Rotate knob
of gas control/gas valve
to “OFF” position.
Step 2. Remove outer jacket door.
Step 3. Remove right side of inner door per
SERVICE PROCEDURE RG-I, steps
3a through 3c.
Step 4 Disconnect thermocouple/thermopile, pilot tube,
and feedline from gas control/gas valve.
NOTE: Feedline nut for natural gas control
uses right hand threads, LP control uses left hand thread.
Step 5 Disconnect piezo ignition wire from piezo igniter.
Step 6. Remove burner assembly from combustion chamber.
Step 7. Remove pilot/electrode assembly from feedline
Step 8. 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 9. 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.
(Honeywell pilot orifice not replaceable, replace pilot assembly)
Step 10. Install pilot/electrode assembly to feedline, secure with screw from step 7.
Step 11. Re-Install burner assembly into combustion chamber, connect feedline,
pilot tube and thermocouple/thermopile to gas conrol/gas valve.
Step 12. Install inner door per SERVICE PROCEDURE RG-I, step 4 through 13.
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.
Primary Air
Opening
The Bradford White
DEFENDER
Safety System®
For White Rodgers Control,
depress knob slightly and rotate
clockwise to the “OFF” position.
For Robertshaw Control, rotate
knob clockwise to the “OFF”
position.
Pilot Orifice
Feedline Nut
SERVICE PROCEDURE RG-III
Pilot Assembly Inspection, Cleaning
and Replacement
For Honeywell Control, rotate
knob counter-clockwise to the
“OFF” position.
13
Removal of thermopile from
Honeywell pilot assembly is not
recommended, but can be
achieved by viewing the pilot
assembly from the top and
pressing the thermopile towards
the right while pulling to remove.
13
13

PIEZO IGNITER, ELECTRODE TESTING AND REPLACEMENT
With the pilot not in operation (no pilot flame) you can check the Piezo and electrode circuit by viewing pilot
thru the sight glass located on the inner door and observing the spark action.
Step 1. Remove outer jacket door.
Step 2. Repeatedly depress the Piezo igniter while viewing the pilot thru the sight glass. If a spark is
present, the circuit is OK. If there is no spark, proceed to step 3.
Step 3 Remove orange (or white) wire from Piezo igniter and install a jumper wire in its place. Hold the
other end of the jumper by the wire insulation or using an insulated tool, next to an unpainted
surface such as the feedline or gas valve and depress the Piezo igniter. If there is a spark, the igniter
is OK, the pilot is not functioning and must be replaced, see SERVICE PROCEDURE RG-III for
pilot replacement. If no spark is present the igniter is not functioning and must be replaced.
Step 4a. For White Rodgers/Robertshaw gas valves: With orange wire disconnected from piezo igniter.
Using a common screw driver, place blade of screw driver under piezo bracket and gently pry
bracket from front of gas valve and unhook bracket from rear of gas valve.
View spark
Action through
Sight glass
Repeatedly
Depress Piezo
Igniter
Common Screw
Driver
The Bradford White
DEFENDER
Safety System®
Step 4b. For Honeywell gas controls: To replace igniter, see “Gas Control Disassembly/Reassembly” in
SERVICE PROCEDURE RG-VI.
SERVICE PROCEDURE RG-IV
Piezo Igniter, Electrode Testing
and Replacement
14
14
14

SERVICE PROCEDURE RG-V
Gas Valve
Testing and Replacement (White Rodgers/Robertshaw)
The gas valve is a non repairable device. If trouble shooting has determined a problem with the gas valve, 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 valve may be faulty.
MANIFOLD PRESSURE TESTING (this procedure assumes a maximum line pressure of 14.0" w.c.)
Step 1. Set gas valve 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 valve 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 valve 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 valve 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 (check rating plate). Line pressure must be checked with burner on and burner off to
assure proper readings.
Pressure Tap
Shown Installed
The Bradford White
DEFENDER
Safety System®
Gas Valve Testing and Replacement (White Rodgers/Robertshaw)
15
15
15

See SERVICE PROCEDURE RG-II
THERMOCOUPLE TESTING
MAGNET ASSEMBLY TESTING (White Rodgers Control)
Step 1. Following the lighting instruction label on the heater, proceed to light the pilot and allow to operate for
three minuets. If the pilot will not stay lit, hold the pilot button (located on the 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 valve.
Probe top terminal on
back of combination
thermostat/gas valve Alligator clip to copper
sheath of thermocouple
Step 6. With a meter reading of 13 millivolts or greater, rotate knob of combination thermostat/gas valve 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 valve should be replaced.
MAGNET ASSEMBLY TESTING (Robertshaw Control)
Step 1. Disconnect thermocouple from gas valve.
Step 2. Connect a thermocouple adaptor
(BWC P/N 239-44642-00, Robertshaw P/N 75036) at the
thermocouple location in the gas valve.
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 valve 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 valve should be replaced.
SERVICE PROCEDURE RG-V
Gas Valve
Testing and Replacement (White Rodgers/Robertshaw)
16
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COMBINATION THERMOSTAT/GAS VALVE REPLACEMENT
Step 1. Rotate knob of the gas valve to the “OFF” position.
Step 2. Turn off gas supply to water heater.
Step 3. Disconnect gas supply line from gas valve.
Step 4. Turn off water supply and drain water heater completely.
Step 5. Remove outer jacket burner access door.
Step 6. Right side inner door removal.
a) Disconnect resettable thermal switch wire leads (leading from gas valve)
and remove wire tie from feedline.
b) Remove (2) hex drive screws from right side inner door.
c) Remove (2) hex drive screws from flange section of inner door.
d) Remove right side inner door and set aside. Be careful not to damage gasket material on inner door.
Resettable Thermal Switch
Wire Connection
Hex Drive Screws shown on
Right Side Inner Door.
Hex Drive Screws at
Flange section of Inner Door
Remove
Wire Tie
For White Rodgers Control,
depress knob slightly and rotate
clockwise to the “OFF” position.
For Robertshaw Control, rotate
knob clockwise to the “OFF”
position.
Step 1. Disconnect thermocouple from gas valve.
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 valve must be replaced.
ECO (Energy Cut Off) TESTING
SERVICE PROCEDURE RG-V
Gas Valve
Testing and Replacement (White Rodgers/Robertshaw)
17
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Step 7. Removal of gas valve.
a) Disconnect main burner feedline, pilot tube and thermocouple
from gas valve & 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 piezo bracket with piezo igniter (refer to SERVICE PROCEDURE RG-IV) from gas valve.
c) Remove gas valve from water 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 valve.
a) Install new gas valve using a control body wrench or a length of ½" NPT
pipe threaded into inlet of control. DO NOT OVER TIGHTEN. Use caution not to damage cast
aluminum body of gas valve. Be certain not to damage the bundled wire leads.
Note: Gas valve 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 Piezo bracket with Piezo igniter to gas valve.
c) Reattach main burner feedline, pilot tube and thermocouple to gas valve.
NOTE: Feedline nut for natural gas control uses right hand threads,
LP control uses left hand thread.
d) Gather wire leads of gas valve and Piezo igniter and secure along side of
feedline using new wire tie provided.
e) 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.
Step 9. Reinstallation of inner door assembly.
a) Prior to reinstallation of inner door, fully inspect inner door gasket for the following:
> Tears > Gasket Adhesion to inner door
> Missing Material > Other imperfections that will inhibit proper seal
> Cracks > Material left on combustion chamber
> Dirt or debris
If the gasket is not effected by any of the above, gasket replacement will not be required. If replacement is
required, replace using new gasket kit following the instructions provided with kit.
To remove or install control, insert
only ½" NPT threaded pipe into inlet
and use to loosen or tighten control.
Wrench Boss
SERVICE PROCEDURE RG-V
Gas Valve
Testing and Replacement (White Rodgers/Robertshaw)
18
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Step 9. Reinstallation of inner door assembly. (cont.)
b) Clean any gasket residue or other debris from combustion chamber surface before installing
the inner door/gasket assembly.
c) Position thermocouple, pilot tube and Piezo wire against left side inner door flange gasket. DO NOT ROUTE
THROUGH RADIUSED CHANNEL WITH FEEDLINE. Be sure that thermocouple and pilot tube are not
in position to interfere with outer jacket burner access door when reinstalled.
Position thermocouple,
pilot tube and Piezo wire.
WARNING
A seal breach may result in a fire or
explosion causing property damage,
personal injury or death.
d) Firmly place right side inner door flange against the left side inner door flange and secure with (2) hex drive
screws from step 6c. DO NOT OVER TIGHTEN SCREWS.
e) Align right side inner door to combustion chamber and verify the fastener holes of the combustion
chamber are aligned with the right side inner door slotted openings. Verify seal integrity around combustion
opening. Secure right side inner door using (2) hex drive screws from step 6b. DO NOT OVER TIGHTEN
SCREWS. Verify both left and right sides of the inner door are properly positioned and sealed against
the combustion chamber.
Step 10. Reconnect wire leads from gas valve to resettable thermal switch (See photo in step 6). Note: wire
terminations are interchangeable with either resettable thermal switch connection.
Step 11. Replace outer jacket burner access door.
Step 12. Reconnect gas supply to gas valve.
Step 13. Resume water supply to water heater. Be sure tank is full of water.
Step 14. To resume operation follow the instructions located on the lighting instruction label or the lighting instructions
located in the installation and operation manual.
Verify threaded hole
alignment with slotted
openings in inner door.
Secure flange with
¼" drive screws.
SERVICE PROCEDURE RG-V
Gas Valve
Testing and Replacement (White Rodgers/Robertshaw)
19
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SERVICE PROCEDURE RG-VI
Gas Control
Testing, Disassembly & Replacement (Honeywell)
The Bradford White
DEFENDER
Safety System®
Honeywell Gas Control Testing, Disassembly, and Replacement
The Gas Control is made up of (5) major components; the control cover, the piezo igniter, the valve body, the temperature
sensor, and the back plate. The Gas Control is designed so that any of these components may be replaced without
replacing the entire Gas Control.
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’s rated manifold pressure (check rating plate). Line pressure must be checked with the main burner on and
off to assure proper readings.
Gas Control
Cover
Piezo Igniter
Valve Body Backplate
Temperature
Sensor
Insertion Stick
Valve Body
Screw
Gas Control
Cover Screw
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