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