Bradford White M-2-TW-75T6BN User Manual
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Manual 238-46238A-00A
SERVICE
MANUAL
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualified service providers)
Models Covered
by This Manual:
M1TW40S*F (BN,CX,SX)
M1TW50S*F (BN,CX,SX)
M1TW60T*F (BN,CX,SX)
M4TW40T*F (BN,SX)
M4TW50T*F (BN,SX)
M4TW60T*F (BN,SX)
M2TW50T*F (BN,CX,SX)
M2TW65T*F (BN,CX,SX)
TW450S65F (B,C,S)*(N,X)
TW465S65F (B,C,S)*(N,X)
(*) Denotes Warranty Years
Through-The-Wall Gas Water Heaters
TTW Series
®
The Bradford White
2
Through-The-Wall Gas Water Heaters
Page TTW Service Procedure
Introduction 4 - - -
How to use this manual 5 - - -
Tool required for service 5 - - -
Specifications 6 - - -
Control Timings 9 - - -
Sequence of Operation 10 - - -
Troubleshooting 13 - - -
Burner Inspection, Cleaning and Replacement 15 I
Pilot Testing, Cleaning and Replacement 17 II
Pressure Switch Testing and Replacement 18 III
Blower Testing and Replacement 20 IV
Blower Temperature Switch Testing and Replacement 22 V
Gas Control & Thermal well Testing & Replacement 24 VI
Flammable Vapor Sensor Testing and Replacement 28 VII
Safety Circuit Voltage Trace 29 VIII
115VAC Circuit Trace 30 IX
Dip Tube inspection and Replacement 31 X
Anode Inspection and Replacement 32 XI
Flue Baffle Inspection and Replacement 33 XII
Inner Door Removal, Inspection & Replacement
®
ScreenLok
Flame Arrestor Cleaning
Glossary of Terms
Parts List
34 XIII
37 XIV
38 - - -
39 - - -
Page 2
Page 2
WARNING: If the information in these instructions
3
is not followed exactly, a fire or explosion may
result causing property damage, personal injury, or
death.
Incorrect operation of this appliance
CAUTION
may create a hazard to life and
property and will nullify the warranty.
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.
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.
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.
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
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.
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.
To
Do not store or use gasoline or other
DANGER
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
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.
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.
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
Page 3
4
Introduction
4
The new Bradford White TTW1, 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 TTW1 (M1TW), TTW2 (M2TW) & 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.
Page
How to Use This Manual
5
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 13 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.
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.
Page 5
Page 5
Specifications
6
Power supply Dedicated 115VAC, 60 Hz, 15A
Gas Supply Pipe Minimum 1/2" NPT (schedule 40 black iron pipe recommended)
Approved Gas Type Natural or Propane. Unit must match gas type supplied.
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.)
Venting System Power vent through the wall or vertical through the roof
Approved Vent Materials PVC, CPVC or ABS
Minimum Clearance
for Servicing
Water Supply Pressure 150 PSI maximum allowable working pressure. Check local codes for supply pressure
Thermal well TCO Limit Residential 188°F (87°C), Commercial 199°F (93°C)
Residential Temperature
Set Point Range
Commercial Temperature
Set Point Range
Blower Temperature
Switch
18" from top, 24" from front, 4" sides and rear.
60°F (16°C) to 160°F (71°C) (Approximate temperatures)
80°F (27°C) to 180°F (82°C) (Approximate temperatures)
Normally closed, opens @ 165°F (74°C), auto reset @ 130°F (54°C).
Pressure switch
Blower
TTW1 (M1TW) Models:
Normally open, closes on vacuum increase @ -.68, opens on vacuum decrease @ -.65
TTW1 (M4TW) Models:
Normally open, closes on vacuum increase @ -.83, opens on vacuum decrease @ -.80
TTW2 (M2TW & TW4) Models:
Normally open, closes on vacuum increase @ -1.28, opens on vacuum decrease @ -1.25
TTW1 (M1TW & M4TW) Models:
115VAC, 60Hz, 3.1 amps, 3000 RPM, 42CFM@1.5" W.C.
TTW2 (M2TW & TW4) Models:
115VAC, 60Hz, 3.1 amps, 3000 RPM, 68CFM@0.4" W.C.
Page 6
Venting Specifications for:
7
40 Gallon
50 Gallon
60 Gallon
Specifications
Vent Tables
2" Diameter (5.1 cm) PVC Vent Connector Lengths
Terminating
Through the Wall
# of
Elbows
1 45 (13.7) 2 (.6)
Maximum Straight
Length ft (m)
Minimum Straight
Length ft (m)
Through the Wall 2 40 (12.2) 2 (.6)
Through the Wall 3 35 (10.7) 2 (.6)
Through the Wall 4 30 (9.2) 2 (.6)
Through the Roof 0 50 (15.2) 7 (2.1)
Through the Roof 1 45 (13.7) 7 (2.1)
Through the Roof 2 40 (12.2) 7 (2.1)
Through the Roof 3 35 (10.7) 7 (2.1)
Through the Roof 4 30 (9.2) 7 (2.1)
3" Diameter (7.6 cm) PVC Vent Connector Lengths
Terminating
Through the Wall
# of
Elbows
1 115 (35.0) 10 (3.1)
Maximum Straight
Length ft (m)
Minimum Straight
Length ft (m)
Through the Wall 2 110 (33.5) 10 (3.1)
Through the Wall 3 105 (32.0) 10 (3.1)
Through the Wall 4 100 (30.5) 10 (3.1)
Through the Wall 5 95 (29.0) 10 (3.1)
Through the Roof 0 120 (36.6) 15 (4.6)
Through the Roof 1 115 (35.0) 15 (4.6)
Through the Roof 2 110 (33.5) 15 (4.6)
Through the Roof 3 105 (32.0) 15 (4.6)
Through the Roof 4 100 (30.5) 18 (5.5)
Page 7
Page 7
Venting Specifications for:
8
48 Gallon
65 Gallon
Specifications
Vent Tables
3" Diameter (7.6 cm) PVC Vent Connector Lengths
Terminating
Through the Wall
# of
Elbows
1 55 (16.8) 2 (.6)
Maximum Straight
Length ft (m)
Minimum Straight
Length ft (m)
Through the Wall 2 50 (15.2) 2 (.6)
Through the Wall 3 45 (13.7) 2 (.6)
Through the Wall 4 40 (12.2) 2 (.6)
Through the Roof 0 60 (18.3) 7 (2.1)
Through the Roof 1 55 (16.8) 7 (2.1)
Through the Roof 2 50 (15.2) 7 (2.1)
Through the Roof 3 45 (13.7) 7 (2.1)
4" Diameter (10.2 cm) PVC Vent Connector Lengths
Terminating
Through the Wall
# of
Elbows
1 10 (3.1)
Through the Wall 2 10 (3.1)
Through the Wall 3 10 (3.1)
Through the Wall 4 10 (3.1)
Through the Wall 5 12 (3.6)
Maximum Straight
Length ft (m)
175 (53.3)
170 (51.8)
165 (50.3)
160 (48.8)
155 (47.2)
Minimum Straight
Length ft (m)
Page 8
Through the Roof 0 15 (4.6)
Through the Roof 1 15 (4.6)
Through the Roof 2 15 (4.6)
Through the Roof 3 15 (4.6)
Through the Roof 4 15 (4.6)
180 (54.9)
175 (53.3)
170 (51.8)
165 (50.3)
160 (48.8)
Page 8
Control Timings
A
9
Ignition State Timing
Pre-purge 2 Seconds
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 (See Page 24 to reset)
Verify Resistive Delay Retry after 2 Minutes (repeats 5 times)
Simulated Resistive Load Lockout Indefinite (cycle power to reset)
Hardware Error Lockout Indefinite (self clears if fault clears for at least 15 seconds)
Specifications
Pilot
Pilot
Wiring Diagram
Wiring Diagram
Blower
Blower
Housing
Housing
B
B
Thermal
Thermal
Well
Well
Blower
Blower
Temperature
Temperature
Switch
Switch
Pressure
Pressure
Switch
Switch
C
C
Simulated
Flammable
Resistive
Vapor
Device
Sensor
Blower
Blower
Motor
Motor
Page 9
Page 9
Sequence of Operation
10
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.
To assure no outputs are energized if the “Flammable Vapor Sensor” is out of range, the control will test the
“Flammable Vapor Sensor” for proper operating range. If the “Flammable Vapor Sensor” is within range the
control resumes normal operation with no perceptible delay. If the “Flammable Vapor Sensor” is out of range,
the control LED immediately flashes 7 times with 3 second pause.
1
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.
2
Blower energizes.
3
Pressure switch proves blower/vent system operation.
If the pressure switch does not close within 30 seconds, the control LED Flashes
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)
5
Trial 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.
6
Main 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.
.3 times with 3 second pause
Page 10
Page 10
Steady state operation.
11
7
During Steady State Operation the Control Monitors:
Thermostat temperature sensor-
blower will post purge for 15 seconds. Control LED flashes a short flash once every 4 seconds (idle) status
code.
Sequence of Operation
When set point temperature is satisfied, gas valve is shut down and
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.
8
Thermostat satisfies
9
Burner off.
10
Blower post purge (15 seconds).
(Control LED flashing once every 4 seconds).
1. Flammable Vapor Sensor 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 65,000 ohms after 30 seconds, the
gas control proceeds to verify resistive delay for 2 minutes and flashes 7 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
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 once with three second pause. The error self clears if the resistance returns to normal range for at
least 15 seconds.
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 three times with three second pause. The error self clears if the fault clears for at least 15 seconds.
b) Thermal well 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.
To reset control, rotate knob of temperature control to the minimum setting for at least 6 seconds before returning
to desired temperature setting.
Page 11
Page 11
Sequence of Operation
12
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 to close - 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 12
Page 12
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