Bradford White TTW 75 SERIES User manual

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Manual 47150A
SERVICE
MANUAL
For Bradford White
TTW®Series Models:
M2TW75T*(BN,CX)
TW475S76(B,C)* (N,X)
(*) Denotes Warranty Years
Gas Water Heaters
TTW 75 SERIES
®
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualified service providers)

Bradford White
TTW Series
Gas Water Heaters
Table of Contents
Page TTW Service Procedure
Introduction 4 - - -
How to use this manual 5 - - -
Tool required for service 5 - - -
Specifications 6 - - -
Control Timings 8 - - -
Sequence of Operation 9 - - -
Troubleshooting 12 - - -
Burner Inspection, Cleaning and Replacement 14 I
Pilot Testing, Cleaning and Replacement 16 II
Pressure Switch Testing and Replacement 17 III
Blower Testing and Replacement 19 IV
Blower Temperature Switch Testing and Replacement 21 V
Gas Control & Thermal well Testing & Replacement 23 VI
Simulated Resistive Device Testing and Replacement 27 VII
Safety Circuit Voltage Trace 28 VIII
115VAC Circuit Trace 29 IX
Dip Tube inspection and Replacement 30 X
Anode Inspection and Replacement 31 XI
Flue Baffle Inspection and Replacement 32 XII
Glossary of Terms 33 - - -
Parts List 35 - - -
Page 2
2

WARNING: If the information in these
instructions is not followed exactly, a fire or
explosion may result causing property damage,
personal injury, or death.
WHAT TO DO IF YOU SMELL GAS
Do not try to light any appliance.
Do not touch any electrical switch; do not use any
phone in your building.
Immediately call your gas supplier from a neighbor's
phone. Follow the gas supplier's instructions.
If 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.
FOR YOUR SAFETY
Do not store or use gasoline or other
flammable, combustible, or corrosive vapors
and liquids in the vicinity of this or any other
appliance.
CAUTION
Incorrect operation of this
appliance may create a hazard to
life and property and will nullify the
warranty.
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.
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.
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
DO NOT ATTEMPT TO LIGHT ANY GAS APPLIANCE
IF YOU ARE NOT CERTAIN OF THE FOLLOWING:
Liquefied petroleum gases/propane gas and
natural gas have an odorant added by the gas
supplier that aids in the detection of the gas.
Most people recognize this odor as a “sulfur” or
“rotten egg” smell.
Other conditions, such as “odorant fade” can
cause the odorant to diminish in intensity, or
”fade”, and not be as readily detectable.
If 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.
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. WARNING
FAILURE TO INSTALL AND MAINTAIN A NEW,
LISTED 3/4” X 3/4” TEMPERATURE AND PRESSURE
RELIEF VALVE WILL RELEASE THE
MANUFACTURER FROM ANY CLAIM THAT MIGHT
RESULT FROM EXCESSIVE TEMPERATURE AND
PRESSURES.
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
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.
Page 3
3

Page 4
Introduction
The new Bradford White TTW2 & TW4 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 additional vent lengths.
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 Thermostat/Gas Control Valve with LED - was developed for ease
of troubleshooting by providing simple diagnostic codes to pinpoint an installation or
component performance issue.
New Powerful Blower - will eliminate problems with difficult venting situations.
Quieter and Cooler Blower Operation - blower noise is significantly reduced for both
interior and exterior environments. Cooler operation increases blower life by reducing bearing
wear and noise.
Rugged Wiring Connections - receptacle type connections promote error free wiring.
Increased Vent Lengths - increased venting performance is achieved while maintaining
Energy Factor & FHSR performance.
The TTW2 & TW4 water heaters use a combustion system were flue gases are combined with
dilution air to reduce the flue gas temperature in the blower. The diluted flue gases are
evacuated to the exterior through low temperature vent materials. The gas control maintains
water temperature, ignition sequence and regulates gas flow. A safety circuit consisting of a
pressure switch and blower temperature switch verifies proper conditions exist for safe and
reliable operation. If a situation outside of normal operating parameters exists, the gas control
diagnostic LED will flash a code to positively identify an operational issue.
This service manual is designed to facilitate problem diagnosis and enhance service efficiency.
To further promote quicker service times the new gas valve can be removed and replaced
without draining the water heater. A special tool is required and will be provided with each gas
valve kit shipped from our Service Parts department.
Please read the service manual completely before attempting service on this new series of
power vent models.
4

Tools Required for Service
It is intended for this manual to be used by qualified service personal for the primary purpose of
troubleshooting and repair of the Bradford White TTW Series water heaters. Understanding the
sequence of operation section of this manual will contribute greatly to troubleshooting the water
heater.
The Honeywell WV4460E Electronic Gas Control will display error codes in the event of abnormal
operation. Error codes are listed in the troubleshooting chart beginning on page 12 of this service
manual. The troubleshooting chart will also indicate the probable cause for the error code and
direct the service professional to a service procedure to properly diagnose the abnormal operation.
In some difficult to diagnose conditions, it may be necessary to isolate the heater from the vent
system to determine the problem.
Contact the Bradford White technical support group immediately if diagnosis can not be made
using the methods described in this service manual.
Page 5
Manometer: A liquid “U” tube type or a digital (magna-helic) type can be used. This
device is used to measure gas and/or air pressure and vacuum.
Multi-Meter: 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.
Electronic Probes: In some cases, standard multi-meter probes will damage or simply
not be effective to obtain certain voltage and ohm reading. It will be
necessary to have special electronic “pin” type multi-meter probes.
These probes are available at most electronic wholesale outlets.
Thermometer: Used to measure water temperature. An accurate thermometer is
recommended.
Water Pressure Gage: Used to measure water supply pressure. Also used to determine tank
pressure by adapting to the drain valve of the heater.
Gas Control Service Tool: BWC part number 239-45991-00. A specialized tool designed to remove
the gas control from gas control thermal well. Available from
your Bradford White parts supplier.
Various Hand Tools: Pipe wrench, channel locks, open end wrenchs (3/8",7/16",½"),
12" crescent wrench, Allen wrench set, screw drivers (common &
Phillips), ¼" nut driver, pliers (common & needle nose), socket set, side
cutters wire cutters, wire strippers, wire crimpers, torpedo level, small
shop vac, step ladder, and flashlight, 5 gallon pail.
How to Use This Manual
5

Specifications
Thermal well TCO Limit Residential 188°F (87°C), Commercial 199°F (93°C)
Residential Temperature
Set Point Range 60°F (16°C) to 160°F (71°C) (Approximate temperatures)
Blower Temperature
Switch Normally closed, opens @ 165°F (74°C), auto reset @ 130°F (54°C).
Blower M2TW75 and TW475S Models:
115VAC, 60Hz, 3.1 amps, 3000 RPM, [email protected]" W.C.
Pressure switch M2TW75 and TW475S Models:
Normally open, closes on vacuum increase @ -1.28, opens on vacuum decrease @ -1.25
Power supply Dedicated 115VAC, 60 Hz, 15A
Approved Gas Type Natural or Propane. Unit must match gas type supplied.
Venting System Power vent through the wall or vertical through the roof
Approved Vent Materials PVC, CPVC or ABS
Gas Supply Pipe Minimum 1/2" NPT (schedule 40 black iron pipe recommended)
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 Pressure 5.0" W.C. min. for Nat gas, 11.0" W.C. min. for L.P. gas, 14.0" W.C. maximum (Nat. & L.P.)
Commercial Temperature
Set Point Range 80°F (27°C) to 180°F (82°C) (Approximate temperatures)
Page 6
6

Specifications
Venting Specifications:
Through the Wall
Terminating # of
Elbows
Maximum
Length ft (m)
Minimum
Length ft (m)
3" Diameter (7.6 cm) PVC Vent Connector Lengths
145 (13.7) 2 (.6)
Through the Wall 240 (12.2) 2 (.6)
Through the Wall 335 (10.7) 2 (.6)
Through the Wall 430 (9.1) 2 (.6)
Through the Wall
Terminating # of
Elbows
Maximum
Length ft (m)
Minimum
Length ft (m)
4" Diameter (10.2 cm) PVC Vent Connector Lengths
1175 (53.3) 10 (3.1)
Through the Wall 2170 (51.8) 10 (3.1)
Through the Wall 3165 (50.3) 10 (3.1)
Through the Wall 4160 (48.8) 10 (3.1)
Through the Roof 050 (15.2) 7 (2.1)
Through the Roof 145 (13.7) 7 (2.1)
Through the Roof 240 (12.2) 7 (2.1)
Through the Roof 335 (10.7) 7 (2.1)
Through the Roof 0180 (54.9) 15 (4.6)
Through the Roof 1175 (53.3) 15 (4.6)
Through the Roof 2170 (51.8) 15 (4.6)
Through the Roof 3165 (50.3) 15 (4.6)
Through the Wall 5155 (47.2) 10 (3.1)
Through the Roof 4160 (48.8) 15 (4.6)
Vent Tables
Page 7
7

Control Timings
Ignition State Timing
Pre-purge 2Seconds
Trial for Ignition 90 Seconds
Flame Stabilization Period 3 Seconds
Inter-purge 15 Seconds
Flame Failure Response Time 1.5 Seconds (2 second. Maximum; 1 second minimum.)
Post-purge 15 Seconds
PS Fault Delay (failed open/close) Retry after 2 Minutes
Soft Lockout Retry after 5 Minutes
TCO Limit Lockout Indefinite (cycle power to restart)
Simulated Resistive Load Lockout Indefinite (cycle power to restart)
Hardware Error Lockout Indefinite (self clears if fault clears for at least 15 seconds)
Verify Resistive Delay Retry after 2 Minutes (repeats 5 times)
Specifications
Page 8
A
C
B
Blower
Motor
Blower
Temperature
Switch
Pressure
Switch
Pilot
Blower
Housing
Wiring Diagram
Simulated
Resistive
Device
Thermal
Well
8

Sequence of Operation
Thermostat calls for heat.
Prior to energizing blower, gas control checks safety circuit to insure the circuit is open. Normal switch positions
in the safety circuit are as follows:
a) Pressure switch normally open.
b) Blower temperature switch normally closed.
If the safety circuit is closed, the control waits 4 seconds, gas control LED flashes 2 times with 3 second pause.
Gas control waits 2 minutes then, blower runs for 30 seconds. This cycle repeats until safety circuit opens.
Power up Sequence
1Start Up.
Upon power up, the control runs a safe-start check with a typical start-up delay of 1-5 seconds.
2Simulated Resistive Load Device Check.
To assure no outputs are energized if the “Simulated Resistive device” is out of range, the control will test the
the device for proper operating range. If the device is within range the control resumes normal operation with no
perceptible delay. If the device is out of range, the control LED immediately flashes 7 times with 3 second pause.
Normal Heating Sequence
1
2Blower energizes.
3
Pressure switch proves blower/vent system operation.
If the pressure switch does not close within 30 seconds, the control LED Flashes 3 times with 3 second pause.
The blower runs for 30 seconds every 2 minutes trying to get the pressure switch or blower temperature switch to
close. This cycle repeats as long as there is a call for heat.
4
Blower pre-purge period (2 seconds)
5Trial for pilot ignition (90 seconds).
a) The gas control lights the pilot by activating spark igniter and gas flow to pilot burner.
b) If flame is not sensed within 90 seconds, igniter and gas flow are deactivated, blower will post purge and
control LED flashes 6 times with 3 second pause.
6Main burner Ignition
After pilot flame is sensed, gas control activates main valve for main burner ignition. The gas control will ignore
flame and pressure switch signals for 3 seconds allowing for main burner to stabilize.
Page 9
9

Steady state operation.
During Steady State Operation the Control Monitors:
Thermostat temperature sensor- When set point temperature is satisfied, gas valve is shut down and
blower will post purge for 15 seconds. Control LED flashes a short flash once every 4 seconds (idle) status
code.
Pressure switch / Blower temperature switch- If either switch opens, pilot valve and main valve is shut
down. The blower continues to runs for 30 seconds attempting to close the circuit. The control LED Flashes
3 times with 3 second pause.
Flame Sensor- If flame is lost, pilot & main valve are shut down, blower runs for 15 seconds. Control attempts
to re-light pilot 4 times. If unsuccessful, Blower is shut down and control proceeds to 5 minute lockout. Control
re-attempts to light pilot starting at normal heating sequence #2.
Thermostat satisfies.
Burner off.
Blower post purge (15 seconds).
9
8
10
7
Sequence of Operation
Abnormal Operation
1. Simulated Resistive Device Fault:
a) If the resistance is greater than 70,000 Ohms - the gas control immediately turns off all outputs. Control waits
and monitors resistance for 30 seconds. If the resistance is greater than 70,000 ohms after 30 seconds, the
gas control proceeds to verify resistive delay for 2 minutes and flashes 8 times then once with a three second
pause. This process is repeated 5 times until the control either returns to normal operation or proceeds to flashing
7 times with a 3 second pause.
b) If the resistance is below 3000 ohms - The gas control immediately turns off all outputs and proceeds to flash
8 times then once with three second pause. The error self clears if the resistance returns to normal range for at
least 15 seconds.
Normal Heating Sequence (cont.)
2. Temperature Sensor Fault:
a) Temperature sensor detected open circuit - The gas control Immediately turns off all outputs and proceeds to
flash 8 times then twice with three second pause. The error self clears if the fault clears for at least 15 seconds.
b) Temperature sensors not reading the same temperature within ±5.5 °F - The gas control Immediately turns off
all outputs and proceeds to flash 8 times then three times with three second pause. The error self clears if the fault
clears for at least 15 seconds.
c) Water temperature in excess of TCO (Temperature Cut Off) limit - The gas control immediately turns off pilot &
main valve and proceeds to flash 4 times with 3 second pause. Blower continues to run until gas control is reset.
Power needs to be cycled to remove gas control from TCO lockout.
Page 10
10

Sequence of Operation
Abnormal Operation (cont.)
3. Pressure Switch/Blower Temperature Fault:
a) Pressure switch closed at start of call for heat - The gas control waits four seconds then, proceeds to flash
2 times with 3 second pause. The control waits 2 minutes and then turns on blower for 30 seconds. The blower
turns off after 30 seconds and the control waits for pressure switch to open. Any time the Pressure switch opens,
the blower turns on (or stays on) and the control proceeds to waiting for pressure switch to close.
b) Pressure switch or blower temperature switch failed open - The gas control runs the blower for 30 seconds
waiting for the pressure switch and/or blower temperature switch to close. If either switch does not close in 30
seconds, the blower turns off and the control flashes 3 times with 3 second pause. The gas control waits two
minutes before turning on the blower for another 30 seconds to see the circuit close. This cycle repeats as long as
there is a call for heat or until the circuit closes.
c) Pressure switch or blower temperature switch opens during burner operation - The gas control turns off the
pilot and main valve, runs blower for 15 seconds (inter-purge) waiting for pressure switch and/or blower
temperature switch to close. If either switch fails to close, the control proceeds as described in 3b above. If the
circuit closes again by the end of the inter-purge, the recycle counter is incremented, 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
turns off the blower and flashes 6 times then 2 times with 3 second pause. The gas control waits 5 minutes before
repeating ignition sequence.
4. Trial For Ignition Fault:
a) Pressure switch opens during trial - The gas control turns off igniter and pilot valve. The gas control proceeds
as described in 3b above. If the pressure switch closes within 30 seconds the gas control will continue with trial for
ignition starting at blower pre-purge.
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 igniter turns off, the pilot valve is closed and the gas control runs the
blower through post purge and flashes 6 times then once with 3 second pause. The control waits 5 minutes before
repeating the ignition sequence.
5. Flame Sensing Fault:
b) Flame lost during run - The gas control turns off pilot and main valves, runs blower for 15 seconds (inter purge).
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 turns off the blower and flashes 6 times
then 3 times with 3 second pause. The gas control waits 5 minutes before repeating the ignition sequence.
c) Flame sensed out of sequence - the gas control only looks for pilot flame when the blower is running. 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.
Page 11
11

Short flash, once every
four seconds
“Heartbeat”, alternates
bright/dim
Thermostat calling
for heat (no fault).
Short flash once per
second
Weak pilot signal
on last call for
heat.
Two flash, three
second pause
Pressure switch
not working-
closed position.
Three flash, three
second pause
Pressure switch
or blower temp.
switch not working
-open position.
Four flash, three
second pause
Excessive tank
temperature.
System must be
reset.
Five flash, three
second pause
Undesired-false
pilot flame
present.
Troubleshooting
LED Status
Stand-by mode,
Waiting for call for
heat (no fault).
Control
Status
Service
Procedure
Probable Cause
Temperature demand is satisfied
Normal operation.
Adjust thermostat to
temp level
Tank temperature below set point of thermostat.
Normal operation.
Adjust thermostat to
temp level
1. Unstable pilot.
2. Pilot tube block or restricted.
3. Oxidation build up on pilot electrode.
4. Wire damage to pilot assembly or bad
connection at gas valve.
1. Page 14
2-4. Page 16
1. Pressure switch tubing kinked or blocked.
2. Blocked pressure tap on switch or blower.
3. Faulty pressure switch.
Page 17
1. Vent blockage or improper vent configuration.
2. Pressure switch tubing kinked or blocked.
3. Faulty pressure switch.
4. Blower not spinning up to speed.
5. Blower temp or exhaust temp too high
6. Faulty blower temperature switch.
1. Check vent or vent tables.
2 & 3 Page 18
4. Page 19
5 & 6 Page 21
1. Thermal well sensor out of calibration.
2. Faulty gas control.
3. Pluming leak
1. Page 23
2. Replace gas control,
page 23
1. Pilot valve stuck in open position. Replace gas control,
page 23
None, control LED not
on or flashing
No electrical
power
Control power switch in “OFF” position.
Supply voltage interrupted. Turn power on
Page 12
Observe green LED indicator on
Electronic 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.
Green LED
Indicator
12

Six-four flash, three
second pause
Undesired-false
pilot flame
sensed.
System auto
resets.
Seven flash, three
second pause
Simulated
Resistive Device
Harness out of
specification.
Eight-one flash, three
second pause
Simulated
Resistive Device
Harness
specification
check.
Thermal well
sensor damaged
or unplugged
Eight-three flash, three
second pause Gas valve
electronics fault
detected
LED Status Control
Status
Service
Procedure
Probable Cause
Pilot valve stuck in open position. Replace gas control,
page 25
Simulated resistive device out of specification. Page 27
Simulated resistive device out of specification. Page 27
1. Damage to thermal well wire.
2. Thermal well sensor resistance out of range. Page 23
1. Control needs to be reset.
2. Control is wet or physically damaged.
1. Interrupt power supply
2. Replace gas control,
page 25
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 25
Troubleshooting
Six-three flash, three
second pause
Pilot flame
extinguished.
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.
5. Insufficient combustion air.
6. Gas pressure is out of specification.
1. Page 14
2-4. Page 16
5. Refer to installation manual
Page 13
Six-two flash, three
second pause
Pressure switch
or blower temp
switch opened
during burner
operation.
System auto
resets.
1. Check vent or vent tables.
2 & 3 Page 17
4. Refer to venting section of
installation manual
5. Page 19
6 & 7 Page 21
1. Vent blockage or improper vent configuration.
2. Pressure switch tubing kinked or blocked.
3. Faulty pressure switch.
4. Vent termination being affected by wind
5. Blower not spinning up to speed.
6. Blower temp or exhaust temp too high
7. Faulty blower temperature switch.
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. Page 14
2-4. Page 16
13

Step 1. With main burner in operation, remove outer jacket door and slide inner door from left to right to open.
Step 2. To adjust for proper burning, loosen the air shutter nut, rotate the air shutter to close the opening in the
burner, then slowly rotate the air shutter open until flame becomes as blue as possible with a minimum of
yellow tips. 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 will result in soot formation.
Step 3. Close inner door and observe burner operation. Burner should operate as adjusted in step 2. If not,
repeat air shutter adjustment compensating for proper burner operation with inner door closed.
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.
Steel burner models self adjust air to gas ratio 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 cast iron burner adjustment below).
Main burner must be free from any debris accumulation that may effect burner operation (see burner cleaning
procedure on page 15).
Burner Inspection and Air Shutter Adjustment.
Cast Iron Burner Air Shutter Adjustment
WARNING
Inner door and burner components may be HOT when performing this operation. Take
necessary precaution to prevent personal injury.
Air Shutter Nut
TTW SERVICE PROCEDURE I
Burner Operation Inspection,
Adjustment, Cleaning and Replacement
Air Shutter
Page 14
14

Burner Cleaning
Step 1. Position gas control power switch to the
“OFF” position and unplug heater from wall
outlet.
Step 2. Turn off gas supply to water heater.
Step 3. Remove outer jacket door and remove inner door.
Step 4. Disconnect pilot tube (7/16 wrench) and
feedline (¾ wrench) from gas control.
Step 5. Disconnect igniter/flame sensor wire from gas control.
Step 6. Remove burner assembly from combustion chamber.
Step 7. Thoroughly inspect burner surface area and burner port area and
remove any loose debris.
Step 8. For cast iron burners, inspect for any debris build up inside
burner casting.
Burner
surface area
Burner
port area
Step 9. Unscrew burner from main burner
orifice. On cast iron burners, loosen
air shutter nut and unscrew feedline
from burner.
Step 10. Remove main burner orifice from
feedline (½" wrench on steel
burners, 3/8" wrench on cast iron)
inspect orifice, clean or replace if
necessary.
Step 11. Reassemble burner and reinstall into water heater. Restore gas supply
and check for gas leaks.
Step 12 To resume operation follow the instruction located on the lighting
instruction label or the lighting instruction located in the installation
and operating manual.
TTW SERVICE PROCEDURE I
Burner Operation Inspection,
Adjustment, Cleaning and Replacement
Page 15
L.P. Main burner
orifice. Left hand
thread
Main burner
orifice
Remove Outer
door.
Remove
inner door
Feedline nut
Pilot tubing nut
Igniter/flame
sense wire
15

TTW SERVICE PROCEDURE II
Pilot testing, Cleaning and Replacement
Pilot Inspection, Testing and Replacement
Step 1. Position gas control power switch to the
“OFF” position and unplug heater from wall
outlet.
Step 2. Turn off gas supply to water heater.
Step 3. Remove outer jacket door and remove inner door.
Remove Outer
door.
Remove
inner door
Feedline nut
Pilot tubing nut
Igniter/flame
sense wire
Step 4. Disconnect pilot tube nut (7/16 wrench) and feedline nut
(¾ wrench) from gas control.
Step 5. Disconnect igniter/flame sense wire from gas control.
Step 6. Remove burner assembly from combustion chamber.
Step 7. Remove pilot assembly from feedline (¼" nut driver).
Step 8. Visually inspect igniter/flame sense wire for damage. Replace
pilot if damage is found.
Step 9. With a multi-meter set to the ohms setting, check continuity
through igniter/flame sense wire. Replace pilot if no continuity.
Step 10. 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
distance of 3/32" (.09) from pilot hood.
Step 11. Visually inspect igniter/flame sense electrode for oxidation
build up. Carefully clean any oxidation using very fine emery
cloth.
Step 13. 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 as necessary.
Step 14. Reassemble pilot and install to feedline. Reinstall burner assembly to water heater. 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 operating manual.
Step 12. Visually inspect pilot tubing for kinks or cracks. If damage is
found replace pilot.
Ferrule
nut
Pilot
orifice
Pilot
hood
Igniter/flame
sense electrode
Igniter/flame
sense wire
Pilot
tubing
Page 16
16

TTW SERVICE PROCEDURE III
Pressure Switch Testing and
Replacement
Pressure Switch Testing WARNING
120 volt potential exposure. Use caution
making voltage checks to avoid personal injury.
Step 1. Position power switch on gas control
to the “OFF” position.
Step 2. Remove the three screws (Phillips screw driver) from control access cover on blower assembly and
remove cover (see photo 1).
Step 3. Carefully remove pressure switch from blower housing (see photo 2)
2
Use a multi-meter set to the
ohms setting. With blower off,
check across pressure
switch terminals.
Are switch contacts open?
(no electrical continuity)
Check tubing and pressure
tap on switch for blockage.
Is there blockage?
Replace switch
(see page 18)
Position gas valve power
switch to the “ON” position
and adjust thermostat
to call for heat,
this will start the blower.
Check with multi-meter, do
pressure switch contacts
close with blower running?
1
With steps 1,2 & 3
complete,
disconnect wire leads from
pressure switch.
Y
N
Y
N
Switch contacts are OK.
See safety circuit trace
(page 28)
Is vent
system
blocked
NSee blower testing
(page 19)
Is blower OK?
Clear blockage
Y
N
Y
N
Correct blower
problem.
Pressure Switch
Slide pressure switch in direction
of arrow while tilting slightly away
from blower housing.
Is vent system length
within vent table
specifications
listed on page 7
Y
Reconfigure vent
system to be
compliant with
vent tables.
N
Y
Pressure switch
wire leads
Page 17
Check tubing and
pressure tap on
switch for blockage.
Is there blockage?
N
Y
17

Pressure Switch Replacement WARNING
120 volt potential exposure. Use caution
to avoid personal injury.
Step 6. Reconnect wires from step 5 to new pressure switch.
Step 7. Reconnect tubing to new pressure switch.
Step 8. Carefully position pressure switch into blower housing.
Step 9. Position gas control power switch to “ON” position and verify proper heater operation.
Step 10. Replace control access cover from step 2.
Step 1. Position gas control power switch
to “OFF” position.
Step 2. Remove the three screws (Phillips screw driver) from control access cover on blower assembly and
remove cover (see photo 3).
Pressure Switch
Slide pressure switch in direction
of arrow while tilting slightly away
from blower housing.
Step 3. Carefully remove pressure
switch from blower
housing (see photo 4)
Step 4. Disconnect tubing from
pressure switch.
(see photo 5)
Step 5. Disconnect yellow wires
from pressure switch
(see photo 6)
TTW SERVICE PROCEDURE III
Pressure Switch Testing and
Replacement
Page 18
3 4
56
18

TTW SERVICE PROCEDURE IV
Blower Testing and Replacement
WARNING
115 volt potential exposure. Use caution when
making voltage checks to avoid personal injury.
Blower Testing
Is there 115VAC
across terminals
shown in photo 12 ?
Incorrect supply
voltage polarity
Determine
power source
problem and
correct.
Does blower energize
Within 2 minutes?
Y
Disconnect cord set
shown in photo 9. Is
there 115VAC across
terminals shown in
photo 11
N
See pressure
switch testing
Page 17
Is there 115 VAC
at wall outlet?
Check power cord
for damage.
Y
N
Disconnect
pressure switch
tubing from blower.
(see photo 8)
Connect
manometer to
pressure tap of
blower.
(see photo 8)
With blower running, and exhaust
adapter removed from top of
blower, is there a negative
pressure of -2.15" to -2.30" W.C.?
Step 1. Position gas control power switch
to “ON” position and adjust control to call for heat.
Step 2. Remove the three screws (Phillips Screw driver)
from control access cover on blower assembly and
remove cover (see photo 7).
Reconnect cord set
shown in photo 9, is
there 115VAC between
blue wire and green
ground wire
(see photo 13)
Replace blower
Does cord set
have electrical
continuity?
Disconnect vent
system from top of
blower and remove
vent adapter.
(see photo 10)
Does blower energize after
2 minutes, run for 30
seconds and shut down?
N
Is there 115vac across
blue and green wires
(see photo 13)
Blower OK
Y
Repair or replace
power cord
Replace blower
Y
N
N
N
N
Y
Y
Y
Y
N
Pressure
switch tubing
Pressure tap
Remove exhaust
adapter
Shown with pressure
switch removed.
Green ground
wire
Blue wire
Replace blower
Y
Determine voltage
problem and correct.
N
Page 19
7
8 9
11 12
13
10
Replace
gas control
Y
Replace
cord set
N
19

TTW SERVICE PROCEDURE IV
Blower Testing and Replacement
Step 1. Position gas control power switch to the “OFF” position.
Step 2. Unplug blower power cord from wall outlet.
Step 3. Disconnect vent system from exhaust adapter on top of
blower.
Step 4. Remove exhaust adapter from blower (blade screw driver)
and retain for use on new blower
Step 5. Unplug cord sets from blower.
Step 6. Remove the three blower mounting screws
(¼" nut driver).
Step 7. Remove blower with gasket from water heater.
Blower Mounting
Screws
Blower
Cord Sets
Step 8. Clean any debris from jacket head of water heater.
Step 9. Set new blower with gasket in place using locating pins on
blower flange to line up with location holes in jacket head.
Be sure not to damage gasket.
Step 10 Secure blower in place using mounting screws from step 6.
Step 11. Re-install exhaust adapter from step 4.
Step 12. Reconnect vent system to
exhaust adapter.
Step 13. Reconnect cord sets from step 5.
Step 14. Plug blower power cord into wall outlet.
Step 15. Position gas control power switch to the “ON” position.
Step 16. Verify proper blower operation.
Locating Pins
on blower flange
Pin location holes in
jacket head
Remove exhaust
adapter and retain for
use on new blower.
Blower removal
Blower Installation
Page 20
20