Bradford White MI30T*F(BN 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
®
National Excelsior Company
www.excelsiorhvac.com
Subject to change without notice.

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
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www.excelsiorhvac.com
Subject to change without notice.

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
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www.excelsiorhvac.com
Subject to change without notice.

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 ¼turn.
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
National Excelsior Company
www.excelsiorhvac.com
Subject to change without notice.

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
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www.excelsiorhvac.com
Subject to change without notice.