Bradford White URG1D30T*N User manual

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Manual 238‐51673‐00A 10/15
SERVICE
MANUAL
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualified service providers)
Models Covered
by This Manual:
URG1D30T*N
URG1D40S*N
URG1D40T*N
URG1D50T*N
(*) Denotes Warranty Years
Gas Water Heaters
Ultra Low NOx
Residential D Series

2
The Bradford White
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2

Ultra Low NOx
Residential D Series
Gas Water Heaters
Table of Contents
Page D Service Procedure
Introduction...................................................................................................................................................4 ---
How to Use This Manual.............................................................................................................................5 ---
Tools Required for Service..........................................................................................................................5 ---
Specifications................................................................................................................................................6 ---
Control Timings............................................................................................................................................7 ---
Sequence of Operation.................................................................................................................................8 ---
Troubleshooting............................................................................................................................................11 ---
Burner Inspection, Cleaning & Replacement............................................................................................14 D-I
Pilot Testing, Cleaning & Replacement.....................................................................................................17 D-II
Damper Removal & Installation.................................................................................................................18 D-III
Gas Control Testing & Replacement..........................................................................................................19 D-IV
Flammable Vapor Device Testing and Replacement ...............................................................................22 D-V
Diptube Inspection & Replacement............................................................................................................23 D-VI
Anode Inspection & Replacement..............................................................................................................24 D-VII
Flue Baffle Inspection & Replacement ......................................................................................................25 D-VIII
Inner Door Removal, Inspection & Replacement.....................................................................................27 D-IX
115 VAC Circuit Trace................................................................................................................................30 D-X
Damper Relay Installation ...........................................................................................................................31 D-XI
Chamber Sensor Testing..............................................................................................................................34 D-XII
Resettable Thermal Switch, Inspection & Replacement ..........................................................................35 D-XIII
ScreenLok® Flame Arrestor Cleaning .......................................................................................................37 ---
Glossary of Terms ........................................................................................................................................38 ---
Parts List........................................................................................................................................................39 ---

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WARNING: If the information in these
instructions is not followed exactly, a fire or
explosion may result causing property damage,
personal injury, or death.
IMPORTANT
Before proceeding, please inspect the
water heater and its components for
possible damage. DONOT install any
water heater with damaged
components. If damage is evident
then please contact the supplier where
the water heater was purchased or the
manufacturer listed on the rating plate
for replacement parts.

WHATTODOIFYOUSMELLGAS!
xDonottrytolightanyappliance.
xDonottouchanyelectricalswitch;donotuseany
phoneinyourbuilding.
xImmediatelycallyourgassupplierfromaneighbor'sphone.
Followthegassupplier'sinstructions.
xIfyoucannotreachyourgassupplier,callthefire
department.
Installationandservicemustbeperformedbyaqualified
installer,serviceagencyorthegassupplier.

DANGER
Do not store or use gasoline or other flammable,
combustible, or corrosive vapors and liquids in
the vicinity of this or any other appliance.
WARNING
DO NOT ATTEMPT TO LIGHT ANY GAS APPLIANCE IF YOU ARE
NOT CERTAIN OF THE FOLLOWING:
xLiquefied petroleum gases/propane gas and natural gas
have an odorant added by the gas supplier that aids in the
detection of the gas.
xMost people recognize this odor as a “sulfur” or “rotten egg”
smell.
xOther conditions, such as “odorant fade” can cause the
odorant to diminish in intensity, or “fade”, and not be as
readily detectable.
xIf you have a diminished sense of smell, or are in any way
unsure of the presence of gas, immediately contact your gas
supplier from a neighbor’s telephone.
Gas detectors are available. Contact your gas supplier, or plumbing
professional, for more information.
WARNING
FAILURE TO INSTALL AND MAINTAIN A NEW, LISTED ¾” X ¾”
TEMPERATURE AND PRESSURE RELIEF VALVE WILL RELEASE
THE MANUFACTURER FROM ANY CLAIM THAT MIGHT RESULT
FROM EXCESSIVE TEMPERATURE AND PRESSURES.
CAUTION
Turn off or disconnect the electrical power supply to the water heater
before servicing. Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and dangerous operation.
Verify proper operation after servicing.
WARNING
Water heaters are heat producing appliances. To avoid damage
or injury, do not store materials against the water heater or vent-
air intake system. Use proper care to avoid unnecessary contact
(especially by children) with the water heater and vent-air intake
components. UNDER NO CIRCUMSTANCES MUST
FLAMMABLE MATERIALS, SUCH AS GASOLINE OR PAINT
THINNER BE USED OR STORED IN THE VICINITY OF THIS
WATER HEATER, VENT-AIR INTAKE SYSTEM OR IN ANY
LOCATION FROM WHICH FUMES COULD REACH THE
WATER HEATER OR VENT-AIR INTAKE SYSTEM
WARNING
Hydrogen gas can be produced in an operating water heater that
has not had water drawn from the tank for a long period of time
(generally two weeks or more). Hydrogen gas is extremely
flammable. To prevent the possibility of injury under these
conditions, we recommend the hot water faucet to be open for
several minutes at the kitchen sink before you use any electrical
appliance which is connected to the hot water system. If
hydrogen is present, there will be an unusual sound such as air
escaping through the pipes as hot water begins to flow. Do not
smoke or have open flame near the faucet at the time it is open.
CAUTION
If sweat fittings are to be used DO NOT apply heat to the nipples
on top of the water heater. Sweat the tubing to the adapter
before fitting the adapter to the water connections. It is
imperative that heat is not applied to the nipples containing a
plastic liner.

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The Bradford White
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Introduction
The new Bradford White Ultra Low NOx Residential Flue Damper water heaters are designed to provide
reliable performance with enhanced standard features. New design features include reliable spark-to-pilot
ignition system, enhanced diagnostics, simplified servicing, significantly quiet operation, and the Bradford
White Defender Safety System.
Spark-to-Pilot Ignition System – employing the spark-to-pilot ignition system promotes reliable and
consistent pilot and main burner ignitions to provide hot water on demand.
Integrated Immersion Thermal Well/Gas Control with LED – was developed for ease of troubleshooting
by providing simple diagnostic codes to pinpoint an installation or component performance issue.
Rugged Wiring Connections – receptacle type connections promote error free wiring.
The gas control maintains water temperature, ignition sequence, and regulates gas flow. If a situation
outside of the normal operating parameters exists, the gas control diagnostic LED will flash a code to
positively identify an operational issue.
Please read the service manual completely before attempting service on this new series of damper models.
How the Safety System Works
During normal operation, most air for combustion is drawn into the water heater through the openings in the
jacket door. This air travels into the burner venturi, mixing with the gas jet. This air is then mixed with gas
inside the burner and drawn to the burner screen and is efficiently combusted producing Ultra Low NOx
emissions. Additional air is drawn through the openings in the jacket. This air travels down and around the
combustion chamber and enters through holes in the 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 combustion products
from the burner.
In the case where trace amounts of flammable vapors are present in the air flowing into the combustion
chamber and burner venturi, the vapors are harmlessly ignited by the burner/pilot flame. If flammable vapors
are in sufficient quantity to prevent normal combustion, the burner and pilot flames are designed to shut
down.
Should the flammable vapors continue to the burner, the flame arrestor plate and burner screen prevent the
flames from traveling backwards and igniting vapors outside of the combustion chamber. The gas control
utilizes a flammable vapor sensor to detect the presence of flammable vapors and shut down if the vapors
achieve a certain level.It is intended for this manual to be used by qualified service personnel for the primary
purpose of troubleshooting and repair of the Bradford White D Series water heaters. Understanding the
sequence of operation section of this manual will contribute greatly to troubleshooting the water heater.
The Honeywell WV4472 electronic gas control will display status codes in the event of abnormal operation.
Status codes are listed in the troubleshooting chart beginning on page 11 of this service manual. The
troubleshooting chart will also indicate the probable cause for the status code and direct the service
professional to a service procedure to properly diagnose the abnormal operation.
Contact the Bradford White technical support group immediately if diagnosis cannot be made using the
methods described in this service manual.

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It is intended for this manual to be used by a qualified service personnel for the primary purpose of the
troubleshooting and repairing of the Bradford White “D” Series water heaters. Understanding the sequence
of operation section of this manual will contribute greatly to troubleshooting the water heater.
The Honeywell WV4472 electronic gas control will display status codes in the event of abnormal operation.
Status codes are listed in the troubleshooting chart beginning on page 11 of this service manual. The
troubleshooting chart will also indicate the probable cause for the status code and direct the service
professional to a service procedure to properly diagnose the abnormal operation.
Contact the Bradford White technical support group immediately if diagnosis connot be made using the
methods described in this service manual.
Tools Required for Service
Manometer:
Multi-Meter:
Electronic Probes:
Thermometer:
Water Pressure Gage:
Various Hand Tools:
A liquid “U” tube type or a digital (magnahelic) type can be used. This
device is used to measure gas and/or air pressure and vacuum.
A digital type is strongly recommended. 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.
In some cases, standard multi-meter probes will damage or simply not be
effective to obtain certain voltage and ohm readings. It will be necessary to
have special electronic “pin” type multi-meter probes. These probes are
available at most electronic wholesale outlets.
Used to measure water temperature. An accurate thermometer is
recommended.
Used to measure water supply pressure. Also used to determine tank
pressure by adapting to the drain valve of the heater.
Pipe wrench, channel locks, open end wrenches (3/8”, 7/16”, 1/2”), 12”
crescent wrench, allen wrench set, screw drivers (common & Phillip’s), 1/4”
nut driver, pliers (common & needle nose), socket set, side cutters, wire
cutters, wire strippers, wire crimpers, torpedo level, small shop vac, step
ladder, flashlight and 5 gallon pail.

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Power supply Dedicated 115 VAC, 60 Hz, 15A
Gas Supply Pipe Minimum 1/2” NPT (schedule 40 black iron pipe recommended)
Approved Gas
Type Natural Gas unit must match gas type supplied
Gas Pressure 6.0” w.c. min., 14.0” w.c. maximum
Venting System Single or Double Wall Metal Vent Pipe
Minimum
Clearance for
Servicing
18” from top, 24” from front, 4” sides and rear
Water Supply
Pressure
150 PSI maximum allowable working pressure. Check local codes for supply
pressure
Gas Control
ECO Limit Residential 188°F (87°C)
Temperature
Setpoint Range 60°F (16°C) to 160°F (71°C) (approximate temperatures)

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Control Timings
Ignition State Timing
Adjust Damper Position and Verify (Open
Position) 15 Seconds
Trial for Ignition 90 Seconds
Flame Stabilization Period 3 Seconds
Re-adjust Damper Position and Verify 15 Seconds
Flame Failure Response Time 1.5 Seconds (2 second maximum; 1 second minimum.)
Adjust Damper Position and Verify (Closed
Position)
15 Seconds
Damper Blade Position Fault (failed open/close) Retry after 2 minutes
Soft Lockout Retry after 5 minutes
ECO Limit Lockout Indefinite (see page 27)
Verify Resistive Delay Retry after 2 minutes (repeats 5 times)
Simulated Resistive Load Lockout Indefinite (cycle power to restart)
Hardware Status Lockout
Indefinite (self clears if fault clears for at least 15
seconds)
Wiring Diagram

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Power Up Sequence
1. Start Up.
Upon power up, the control runs a safe-start check with a typical start-up delay of 5
seconds.
2. Flammable Vapor.
The gas control verifies that the Flammable Vapor Sensor is in the proper operating
range prior to energizing any components. If the sensor is within the proper range,
the gas control resumes normal operation. If the Flammable Vapor Sensor is out of
range, the gas control LED immediately flashes 7 times with a 3 second pause.
Normal Heating Sequence
When the phrase “Damper Open” is used, this means that the damper blade is in
the vertical position (open). Alternatively, “Damper Closed” means that the damper
blade is in the horizontal position (closed). This must not be confused with the
phrase “Damper Circuit Open,” as this means that the damper blade is in the
horizontal position. “Damper Circuit Closed” means that the damper blade is in the
vertical position, and the water heater can proceed to an ignition trial.
1. Thermostat calls for heat.
Prior to energizing damper, gas control verifies the damper safety circuit to ensure it
is in the correct state. If the safety circuit is closed, the gas control LED flashes 2
times with a 3 second pause. The gas control waits 2 minutes. Then, the damper
is powered closed. This cycle repeats until the safety circuit opens.
2. Damper Powered Open.
3. Damper Safety Circuit Check:
If the damper safety circuit does not close within 30 seconds, the gas control LED
flashes 3 times with 3 second pause. The damper is powered open for a maximum
of 30 seconds every 2 minutes trying to close the damper safety circuit. This cycle
repeats as long as there is a call for heat.
4. Damper hold period (15 seconds).
5. Trial for pilot ignition (90 seconds): The gas control lights the pilot by activating the
spark igniter and gas flow to the pilot burner. If flame is not sensed within 90
seconds, the spark igniter and gas flow are deactivated. The damper will remain
open, and the gas control LED flashes 6 times with a 3 second pause.
6. Main burner ignition: After the pilot flame is sensed, the gas control activates the
main valve for main burner ignition. The gas control will ignore flame signals for 3
seconds to allow for the main burner to stabilize

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Normal Heating Sequence (cont.)
7. Steady state operation.
During steady state operation, the control monitors:
Thermostat Temperature Sensor-when setpoint temperature is satisfied, gas
valve is shut down and damper is powered closed. The gas control LED flashes a
short flash once every 4 seconds (idle) status code.
Damper Position-if the damper position is altered during a call for heat, the pilot
and main valves are shutdown. The damper is powered open attempting to close
the damper safety circuit. The gas control LED flashes 3 times with a 3 second
pause.
Flame Sensor-if flame is lost, pilot & main valves are shut down. The damper is
powered open. The gas control attempts to re-light the pilot 4 times. If
unsuccessful, the damper is closed, and the gas control proceeds to a 5 minute
lockout. The gas control re-attempts to light the pilot starting at normal heating
sequence #2.
8. Thermostat satisfies. (Gas Control LED flashing once every 4 seconds).
9. Burner off.
10.Damper Powered Closed (15 seconds).
Abnormal Operation
1. Flammable Vapor Sensor Fault:
a. If the Resistance is Greater than 70,000 Ohms-the gas control
immediately turns off all outputs. The gas control waits and monitors
resistance for 30 seconds. If the resistance is greater than 65,000 ohms
after 30 seconds, the gas control proceeds to verify resistive delay for 2
minutes and flashes 7 times, then 1 time with a 3 second pause. This
process is repeated 5 times until the control either returns to normal
operation or proceeds to flammable vapor lockout.
b. If the Resistance is Below 3000 Ohms-The gas control immediately turns
off all outputs and proceeds to flash 8 times, then 1 time with a 3 second
pause. The status self clears if the resistance returns to normal range for at
least 15 seconds.
2. Temperature Sensor Fault:
a. Temperature Sensor Open Circuit–The gas control immediately turns off
all outputs and proceeds to flash 8 times then, 3 times with 3 second pause.
The status self clears if the fault clears for at least 15 seconds.

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Abnormal Operation (cont.)
b. Thermal Well Sensor Not Reading the Same Temperature Within ±5.5°F
–The gas control immediately turns off all outputs and proceeds to flash 8
times, then 3 times twice with 3 second pauses. The status self clears if the
fault clears for at least 15 seconds.
c. Water Temperature in Excess of ECO (Energy Cut Out) Limit -The gas
control immediately turns off pilot & main valves and proceeds to flash 4
times with a 3 second pause. To reset the gas control, rotate the setpoint
knob to the minimum setting for at least 6 seconds before returning to
desired temperature setting.
3. Damper Safety Circuit Fault:
a. Damper Failed to Open-The gas control proceeds to flash 3 times with a 3
second pause. The gas control waits 5 minutes, and then tries to open the
damper again.
b. Damper Failed to Close-the gas control proceeds to flash 2 times with a 3
second pause. The gas control waits 5 minutes, and then tries to open the
damper again.
4. Trial for Ignition Fault:
a. Damper Jostled During Trial-The gas control stops the trial for ignition.
The gas control proceeds to flash 3 times with a 3 second pause. The gas
control waits 5 minutes, and then tries to open the damper again.
b. Flame Not Sensed-The gas control energizes the spark igniter attempting to
light the pilot and prove flame. If flame is not sensed within 90 seconds, the
spark igniter turns off, the pilot valve is closed. The gas control LED flashes
6 times, then 1 time with a 3 second pause. The gas control waits 5 minutes
before repeating the ignition sequence.
5. Flame sensing fault:
a. Flame Lost During Run-The gas control turns off pilot and main valves.
The gas control increments the recycle count, if the recycle count has not
reached its limit (4), another trial for ignition begins. If the recycle count has
been reached, the gas control LED flashes 6 times, then 3 times with a 3
second pause. The gas control waits 5 minutes before repeating the ignition
sequence.
b. Flame Sensed Out of Sequence-the gas control only looks for pilot flame
when the damper is in the open position. If flame is present when the pilot
valve is not open, the gas control proceeds to wait for flame loss and flashes
5 times with 3 second pause. This continues until flame is lost. Once the
flame signal is lost, the control flashes 6 times then, 4 times with 3 second
pause. The control waits 5 minutes before repeating the ignition sequence.

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Observe green LED indicator on
electronic gas control. Status 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 Service Procedure
None, control
LED not on or
flashing
No electrical
power
Control power switch in “OFF” position.
Supply voltage interrupted. Turn power on.
One short flash,
once every two
seconds
Stand-by mode,
Waiting for call
for heat (no fault).
Temperature demand is satisfied.
Normal operation.
Adjust thermostat to
temp level.
“Heartbeat”
alternates
bright/dim
Thermostat
calling
for heat (no fault).
Tank temperature below setpoint of
thermostat.
Normal operation.
Adjust thermostat to
temp level.
Short flash once
per second
Weak pilot signal
on last call for
heat.
1. Unstable pilot.
2. Pilot tube blocked or restricted.
3. Oxidation build up on pilot electrode.
4. Wire damage to pilot assembly or bad
connection at gas valve.
1. See burner
inspection on Page
16.
2-4. See Pilot
Inspection, Testing
and Replacement
on page 16.
Two flash, three
second pause
Damper test
circuit not
working
1. Damper not in proper position or
malfunctioning-stuck in open position.
2. Obstructed venting.
3. Faulty damper.
1. Verify cord sets are
fully plugged in
2. Verify switch on
damper is in
“Automatic” position.
3. Replace damper, see
page 17.
Three flash,
three second
pause
Damper test
circuit not
working.
1. Damper not in proper position or
malfunctioning-not reaching full open
position.
2. Obstructed venting.
3. Faulty damper.
1. Verify cord sets are
fully plugged in
2. Verify switch on
damper is in
“Automatic” position.
3. Replace damper, see
page 17.
Four flash, three
second pause
Excessive tank
temperature.
System must be
reset.
1. Temperature sensor out of calibration.
2. Faulty gas control.
Replace gas control,
page 21.
Five flash, three
second pause
Undesired-false
pilot flame
present.
1. Pilot valve stuck in open position. Replace gas control,
page 21.

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LEDStatus ControlStatus ProbableCause Service Procedure
Six-one
flash, three
second
pause
Failed to light
pilot.
System auto
resets.
1. Unstable pilot.
2. Pilot tube blocked or restricted.
3. Oxidation build up on pilot electrode.
4. Wire damage to pilot assembly or bad
connection at gas valve.
1. See Burner Inspection on
page 14.
2. See Pilot Inspection,
Testing and Replacement
on page 16.
Six-two
flash, three
second
pause
Damper test
circuit not
working properly
during burner
operation, system
auto resets after
(5) minutes.
1. Damper not in proper position or
malfunctioning-damper moved from full
open position during run cycle.
2. Obstructed venting.
3. Faulty damper.
4. Damper jostled during run cycle.
Page 17.
Six-three
flash, three
second
pause
Pilot flame
extinguished.
System auto
resets.
1. Unstable pilot.
2. Pilot tubing kinked or blocked.
3. Oxidation build-up on pilot electrode.
4. Wire damage to pilot assembly or bad
connection at gas control.
5. Insufficient combustion air.
6. Insufficient gas pressure.
1-4. Page 16.
5-6. Refer to Installation &
Operation Manual.
Six-four
flash, three
second
pause
Undesired-false
pilot flame
sensed.
System auto
resets.
Pilot valve stuck in open position. Replace gas control,
Page 21.
Seven flash,
three
second
pause
Flammable vapor
sensor or
resettable
thermal switch
fault detected.
1. Flammable vapor present
2. Flammable vapor sensor exposed to
excessive moisture
3. Flammable vapor sensor exposed to
extreme ambient temperature
4. Resettable thermal switch open
1-3. Flammable sensor
testing, Page 22.
4. Resettable thermal switch
testing, Page 33.
Eight-one
flash, three
second
pause
Flammable vapor
sensor out of
specification.
Flammable vapor sensor out of
specification. Page 21.
Eight-two
flash, three
second
pause
Temperature
sensor fault.
1. Damage to temperature sensor wire.
2. Temperature sensor resistance out of
range.
Replace gas control,
Page 21.
Eight-three
flash, three
second
pause
Gas control
electronics fault
detected.
1. Control needs to be reset.
2. Control is wet or physically damaged.
1. Interrupt power supply
2. Replace gas control, page
21.
Eight-four
flash, three
second
pause
Gas valve fault
detected.
1. Control needs to be reset.
2. Control is wet or physically damaged.
1. Interrupt power supply
2. Replace gas control, page
21.

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
LEDStatus ControlStatus ProbableCause Service Procedure
Nine-One flash,
three second
pause
Insufficient
combustion air
detected.
Insufficient combustion air Page 37.
Nine-two flash,
three second
pause
Chamber
temperature
sensor out of
specification
1. Chamber sensor out of calibration.
2. Possible short.
Test Chamber door
sensor on page 34

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Burner Inspection
At periodic intervals (every 6 months) a visual inspection should be made of the pilot and main
burner for proper operation and to assure no debris is accumulating.
Pilot flame should be stable, some causes for an unstable pilot flame are:
a) Water heater vent is less than the allowable vent length.
b) Gas pressure is out of specification.
c) Pilot flame not fully engulfing spark/flame sensor.
Main burner should light smoothly from pilot and burn with a blue flame with a minimum of yellow
tips.
Main burner must be free from any debris accumulation that may affect burner operation (see
burner cleaning procedure on page 15).

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Burner Cleaning
Step 1. Position the gas control power
switch to the “OFF” position and
unplug the heater from the wall
outlet.
Step 2. Turn off gas supply to the water
heater.
Step 3. Remove outer jacket door.
Step 4. Disconnect pilot tube (7/16” wrench)
and feedline (¾” wrench) from gas
control.
Step 5. Disconnect igniter/flame sensor
wire, damper wire harness and FV
wire harness from the gas control.
Step 6. Remove the (4) ¼” hex drive
screws holding the right side inner
door in place.
Step 7. Remove the (3) ¼” hex drive
screws holding the left side burner
door in place.
Step 8. Remove burner assembly from
combustion chamber.

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Burner Cleaning (cont.)
Step 9. Remove manifold mount from
burner inner door by removing (2)
¼” hex drive screws.
Step 10. Use a stiff brush, compressed air
and/or a vacuum to remove any
debris build up from the manifold
mount.
Step 11. Thoroughly inspect burner surface
area and burner port area and
remove any loose debris using
compressed air and/or a vacuum.
Step 12. Thoroughly inspect burner screen
and burner venturi and remove any
loose debris accumulation. Inspect
burner screen for any openings
larger than the normal screen
openings.
Step 13. Remove main burner orifice from
feedline (
1/2” wrench) inspect
orifice, clean or replace if
necessary.
Step 14. Reassemble burner and reinstall
inner door with gasket into water
heater per service procedure IX on
page 26. Restore gas supply and
check for gas leaks.
Step 15. To resume operation, follow the
instruction located on the lighting
instruction label or the lighting
instruction located in the
installation and operation manual.

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Pilot Testing and Replacement
Step 1. Visually inspect
igniter/flame sense
electrode for oxidation
build up. Carefully clean
any oxidation using very
fine emery cloth.
Step 2. Remove pilot assembly
from the burner
assembly (¼” nut driver).
Step 3. Visually inspect
igniter/flame sense wire
for damage. Replace
pilot if damage is found.
Step 4. With a multi-meter set to ohms setting, check continuity through igniter/flame
sense wire. Replace pilot if no continuity.
Step 5. Visually inspect igniter/flame sense electrode for deterioration. Replace pilot
as necessary. Electrode should not be in contact with pilot hood, if so,
carefully adjust electrode to a gap of distance of 3/32” (.09) from pilot hood.
Step 6. Visually inspect pilot tubing for kinks or cracks. If damage is found, replace
pilot.
Step 7. Inspect pilot tubing and pilot orifice for blockage:
a. Remove ferrule nut from bottom of pilot assembly (7/16” wrench).
b. Remove pilot tube and pilot orifice.
c. Inspect pilot tubing and pilot orifice for blockage. Clean or replace pilot as
necessary.
Step 8. Reassemble pilot and install on burner. Reinstall inner door assemblies to water
heater per service procedure IX on page 26.
Step 9. Restore gas supply and check for gas leaks.
Step 10.To resume operation, follow the instruction located on the lighting instruction
label or the lighting instruction located in the installation and operation
manual.

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ULN Res. D Series
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Damper Removal & Installation
Step 1. Position the power switch on the gas
control to the “OFF” position and unplug
the water heater from the wall outlet.
Step 2. Disconnect the vent system from the draft
hood that is mounted on top of the damper
Step 3. Remove the draft hood from the damper
and retain it for use on the new damper.
Step 4. Disconnect the cord sets from the damper.
Step 5. Remove the two mounting screws from the
damper using a ¼” nut driver and retain for
later.
Step 6. Carefully remove the damper from the top
of the water heater.
Step 7. Clean any debris from the jacket head of
the water heater.
Step 8. Set the new damper in place using the
water heater tank flue and the screw holes
in the jacket head.
Step 9. Secure the damper in place using the
screws from step 5.
Step 10. Re-install the draft hood from Step 3.
Step 11. Reconnect the vent system to the draft
hood.
Step 12. Reconnect the cord sets from step 4.
Step 13. Plug the water heater into the wall outlet.
Step 14. Position the gas control power switch to
the “ON” position.
Step 15. To resume operation, follow the instructions located on the lighting
instruction label or the lighting instructions located in the installation and
operation manual.

19
ULN Res. D Series
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
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.
Manifold Pressure Testing
(this procedure presumes a maximum
line pressure of 14.0” W.C.)
Step 1. Set the Gas Control to the “OFF” position.
Step 2. Remove pressure tap plug and install 1/8”
NPT pipe, coupling & pressure tap.
Step 3. Connect manometer to pressure tap.
Step 4. Follow instructions located on the lighting
instructions label and proceed to light the
main burner and observe manometer
reading.
Step 5. Proper operating range for Natural Gas is
5.0” ±0.5” W.C.
Step 6. If pressure is within the range specified in
the previous step, set Gas Control knob to
the “OFF” position, remove manometer
and pressure tap, and replace pressure
tap plug. Check for gas leaks prior to
placing water heater back into operation
by following the instructions located on
the lighting label, or the lighting
instructions located in the installation and
operation manual.
Step 7. If gas pressure is outside the specification
noted above, refer to page 20 to replace
gas control or valve body.

20
ULN Res. D Series
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
ECO (Energy Cut Out)
The Honeywell gas control is designed with an ECO device that will reset.
To reset the gas control after a status code (4), turn the gas control knob to the “OFF”
position and wait a minimum of (5) minutes before relighting following the instructions
located on the lighting instruction label or the lighting instructions located in the
installation and operation manual.
Determine Water Temperature Inside Tank
Step 1. Position gas control power switch to “OFF” position.
Step 2. Draw approximately 4 gallons of water from the drain valve into a container
and discard. Draw an additional gallon and immediately measure water
temperature using an accurate thermometer (It may be necessary to open
a hot water faucet to allow heater to drain).
Step 3. Compare the measured water temperature with the setting on the gas
control. In most instances, they should not differ by more than approx.
10°F.
WARNING
Stored water may be HOT WHEN PERFORMING THE FOLLOWING STEPS IN
THIS PROCEDURE. Take necessary precaution to prevent personal injury.