Bradford-White 55X80B-N, 25X78B-N, GX155S-BN, M1XR65T-BN, 75T80-BN User Manual
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SERVICE
MANUAL
Atmospheric Gas Water Heaters
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by qualified service providers)
Save this manual for future reference
Manual 238-46647-00A
Models Covered
by This Manual :
GX225S*BN
GX155S*BN
25X78B*N
55X80B*N
M1XR65T*(BN,CX)
MI75S*(BN,CX)
M2XR75S*(BN,CX)
MI100T*(BN,CX)
65T65*(BN,CX)
75T80*(BN,CX)
(*) Denotes Warranty Year
Table of Contents
Page Service Procedure
Trouble shooting Chart 3 - - -
Thermocouple Testing and Replacement 4 AG-I
Pilot Assembly Inspection Cleaning and Replacement 5 AG-II
Combination Thermostat/Gas Valve Testing and Replacement 6 AG-III
Burner Operation Inspection, Adjustment, Cleaning and Replacement 10AG-IV
Dip Tube and Anode Inspection and Replacement 13 AG-V
Page 2
2
Troubleshooting Chart
SYMPTOM PROBABLE CAUSE CORRECTIVE ACTION
Pilot will not light
1
. No incoming gas or too low g as
pressure.
2
. Gas control knob set to wrong position.
3
. Pilot light button not being fully
d
epressed when attempting to light pilot.
4. Pilot orifice or pilot tube is obstructed or
k
inked.
1. Poor thermocouple connection at
c
ombination thermostat/gas valve.
2. Thermocouple not fully engaged in pilot
assembly bracket.
3. Pilot flame is not fully envelopin g 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.
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 sa tisfied.
3. Insufficient gas supply or low gas
pressure.
4. Combination thermostat/gas valve ha s
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 period s.
4. Incorrectly sized water he ater 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.
7. Integrated mixing device is set too low for
desired water temp erature.
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.
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 ma gnet ope ration an d replace
combination thermostat/gas valve if
necessary.
1. Adjust temperatu re dial on combination
thermostat/gas valve.
2. Check temperature dial setting on
combination thermostat/gas valve.
3. Check gas supply an d line pressure.
4. Check combination thermostat/gas valve
for proper operation, replace if
necessary.
1. Verify adequ ate combustion air is available
to the unit. Check and clear Jacket slot
openings of any dirt, dust, restrictions or
other obstructions.
2. Check ventin g for proper sizing and proper
operation
3. Check gas supply an d 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 b e nece ssary 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.
7. Reset device using the procedure
in the instructions included with the device.
SERVICE
PROCEDURE
1
. See Service Procedure
AG-III, Page 6.
4
. See Service Procedure
AG-II, Page 5.
4. See Service Procedure
AG-I, Page 4
5. See Service Procedure
AG-III, Page 6
6. See Service Procedure
AG-III, Page 6
2. See Installation &
operation manual.
3. See Service Procedure
AG-III, Page 6
4. See Service Procedure
AG-III, Page 6
3. See Service Procedure
AG-III, Page 6
5. See Service Procedure
AG-III, Page 6
6. See Service Procedure
AG-V, Page 13
Page 3
3
THERMOCOUPLE REPLACEMENT
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. Slide open inner combustion chamber door.
Step 4 Disconnect thermocouple from combination thermostat/gas valve (3/8" wrench). Locate other end of
thermocouple inside of combustion chamber and remove from pilot bracket. Pullfirmly 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 combination thermostat/gas valve (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
Thermocouple Testing and Replacement
Page 4
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
Thermocouple position
4
PILOT ASSEMBLY INSPECTION,
CLEANING AND REPLACEMENT
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. Slide open inner combustion chamber door.
Step 4 Disconnect thermocouple (3/8" wrench), pilot tube (7/16" wrench),
and feedline (¾" wench) from combination thermostat/gas valve.
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 (¼" drive tool)
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 Assembly Inspection, Cleaning
and Replacement
Step 9. Install pilot assembly to feedline, secure with screw from step 7.
Step 10. Re-Install burner assembly into combustion chamber, connect feedline, pilot tube and thermocouple
to combination thermostat/gas valve.
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.
Page 5
Primary Air
Opening
R
F
or White Rodgers Control,
depress knob slightly and rotate
clockwise to the “OFF ” position.
For Robertshaw Co ntrol, rotate
k
nob clockwise to the “OFF”
p
osition.
Pilot Orifice
Feedline
Nut
5
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