Bradford-White U2TW65T-FRN, UTW450S60FR-N, U1TW50S-FRN, UTW465S60FR-N, U1TW60T-FRN User Manual

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TTW® Eco-Defender

Residential U a Low N

er Heaters

S ICE MANUAL

T eshooting Guide a structions for Service

(To be performed ONLY by

qua

ce providers)

M

Covered

b

 

U1TW40

U1TW50

U1TW60T*FRN

U2TW50T*FRN

U2TW65T*FRN

UTW450

UTW465

(*) Denotes Warra y Years

M

l 238-48385-00A

Save this manual for future reference

Table of Contents

Section

Page

Introduction ______________________________________________5 How to Use this Manual _____________________________________6 Tools Required for Service ___________________________________7 Specifications _____________________________________________8 Sequence of Operation_____________________________________ 12

Power Up Sequence Normal Heating Sequence Abnormal Operation

Troubleshooting __________________________________________ 17 Burner Maintenance _______________________________________ 20

Burner Inspection

Burner Cleaning Procedure

Pilot Maintenance _________________________________________ 22 Pilot Inspection Testing and Replacement

Pressure Switch Testing and Replacement _____________________ 25 Blower Testing and Replacement _____________________________ 28 Blower Temperature Switch Testing and Replacement ____________ 31 Thermal Well Testing ______________________________________ 34 Determine Water Temperature Inside Tank_____________________ 35 Gas Control and Thermal Well Testing and Replacement __________ 36 Flammable Vapor Sensor Testing and Replacement ______________ 40 115 VAC Circuit Trace _____________________________________ 40 Safety Circuit Voltage Trace_________________________________ 42 Flue Baffle Inspection and Replacement _______________________ 43 Diptube Inspection and Replacement _________________________ 44 Anode Inspection and Replacement___________________________ 45 Inner Door Removal, Inspection and Replacement _______________ 46 Inner Door Gasket Replacement _____________________________ 47 Inner Door Installation_____________________________________ 48 ScreenLok ® Flame Arrestor Cleaning_________________________ 49 Common Terms __________________________________________ 50 Notes __________________________________________________ 50 Parts List _______________________________________________ 51

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:

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.

CAUTION

Incorrect operation of this water heater may create a hazard to life and property and will nullify the warranty.

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.

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.

NOTICE

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.

Page 3

3

WARNING

Water heaters are heat producing appliances. To avoid damage or injury, do not store materials against the water heater or any of its components. Use proper care to avoid unnecessary contact, especially by children, with the water heater and its components. Under no circumstances must flammable materials, such as gasoline or paint thinner be used or stored in the vicinity of this water heater or in any location in which the fumes could reach the water heater.

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 a 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.

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.

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.

Page 4

4

Introduction

The Bradford White ECO-DEFENDER Safety System®

The Bradford White ECO-DEFENDER Safety System was designed to resist the ignition of flammable vapors that can occur outside of the water heater and produce Ultra Low NOx emissions. Use and installation are nearly identical to previous versions of atmospherically fired and vented water heaters. A number of exclusive design features are incorporated in the system that will require additional knowledge on the part of the qualified service provider. The following information will instruct service professionals on the function, proper diagnosis, and repair of water heaters employing the Bradford White ECO-DEFENDER Safety System.

Introduction

The new Bradford White TTW ECO-DEFENDER 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, quiet operation, additional vent lengths, Bradford White ECO-DEFENDER Safety System ® and Ultra Low NOx emissions.

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.

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 and FHSR performance.

The TTW1, 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

Page 5

5

How to Use this Manual

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

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. This causes the thermopile to overheat and shuts down the main pilot and burner. The thermopile powers the intelligent diagnostic control which is capable of recognizing restricted airflow conditions caused by severe lint, dust and oil accumulation on the burner screen and arrestor plate. The intelligent diagnostic control will deactivate the burner and pilot in the unlikely event of restricted airflow.

How to Use this Manual

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 Residential Flue Damper 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.

Page 6

6

Tools Required

Contact the Bradford White technical support group immediately if diagnosis cannot be made using the methods described in this service manual.

Tools Required for Service

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 wrenches (3/8", 7/16", 1/2"), 12" crescent wrench, Allen wrench set, screw drivers (common & Phillips), 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.

Page 7

7

Specifications

 

Power Supply

Dedicated 115VAC, 60 Hz, 15A.

 

 

 

 

 

 

Gas Supply Pipe

Minimum 1/2” NPT (schedule 40 black iron pipe recommended).

 

 

 

 

 

 

Approved Gas Type

Natural Gas.

 

 

 

 

 

 

Gas Pressure

6.0” W.C. minimum, 11.0” W.C. maximum.

 

 

 

 

 

 

Venting System

Power vent through the wall or vertical through the roof.

 

 

 

 

 

 

Approved Vent Materials

PVC, CPVC or ABS.

 

 

 

 

 

 

Minimum clearance for

18” from top, 24” from front, 4” sides and rear.

 

 

Servicing

 

 

 

 

 

 

 

 

 

Water Supply Pressure

150 PSI maximum allowable working pressure. Check local codes for

 

 

supply pressure.

 

 

 

 

 

 

 

 

 

TCO Limit

Residential 118oF (87oC), Commercial 199oF (93oC).

 

 

 

 

 

 

Residential Temperature

60oF (16oC) to 160oF (71oC) (approximate temperatures).

 

 

Set Point Range

 

 

 

Commercial Tempera-

80oF (27oC) to 180oF (82oC) (approximate temperatures).

 

 

ture Set Point Range

 

 

 

 

 

 

 

 

 

Blower Temperature

Normally closed, opens @ 165oF (74oC), auto reset @130oF (54oC)

 

 

Switch

 

 

 

 

 

 

 

 

 

 

UTW1 Models:

 

 

 

Normally open, closes on vacuum increase @ -0.68, opens on vacuum

 

 

Pressure Switch

decrease @ -0.65

 

 

U2TW Models:

 

 

 

 

 

 

Normally open, closes on vacuum increase @ -1.28, opens on vacuum

 

 

 

decrease @-1.25

 

 

 

 

 

 

 

UTW1 Models:

 

 

Blower

115VAC, 60Hz, 3.1 amps, 3000 RPM, 42 CFM @ 1.5” W.C.

 

 

U2TW Models:a,

 

 

 

 

 

 

115VAC, 60Hz, 3.1 amps, 3000 RPM, 68 CFM @ 0.4” W.C.

 

 

 

 

 

Page 8

8

Specifications

Vent Tables

Venting Specifications for:

40 Gallon—40,000 BTU/hr.

50 Gallon—40,000 BTU/hr.

60 Gallon—42,000 BTU/hr.

2” Diameter (5.1 cm) PVC Vent Connector Lengths

Terminating

 

# of Elbows

Maximum Straight

 

Minimum Straight

 

Length ft (m)

 

Length ft (m)

 

 

 

 

 

 

 

 

 

 

Through the Wall

 

1

45 (13.7)

 

2 (0.6)

 

 

 

 

 

 

Through the Wall

 

2

40 (12.2)

 

2 (0.6)

 

 

 

 

 

 

Through the Wall

 

3

35 (10.7)

 

2 (0.6)

 

 

 

 

 

 

Through the Wall

 

4

30 (9.2)

 

2 (0.6)

 

 

 

 

 

 

 

 

 

 

 

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

 

# of Elbows

Maximum Straight

 

Minimum Straight

 

Length ft (m)

 

Length ft (m)

 

 

 

 

 

 

 

 

 

 

Through the Wall

 

1

115 (35.0)

 

10 (3.1)

 

 

 

 

 

 

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)

 

15 (4.6)

 

 

 

 

 

 

 

Page 9

9

Specifications

Vent Tables

Venting Specifications for:

48 Gallon—60,000 BTU/hr.

65 Gallon—60,000 BTU/hr.

3” Diameter (7.6 cm) PVC Vent Connector Lengths

Terminating

# of Elbows

Maximum Straight

Minimum Straight

Length ft (m)

Length ft (m)

 

 

 

 

 

 

Through the Wall

1

55 (16.8)

2 (0.6)

 

 

 

 

Through the Wall

2

50 (15.2)

2 (0.6)

 

 

 

 

Through the Wall

3

45 (13.7)

2 (0.6)

 

 

 

 

Through the Wall

4

40 (12.2)

2 (0.6)

 

 

 

 

 

 

 

 

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

# of Elbows

Maximum Straight

Minimum Straight

Length ft (m)

Length ft (m)

 

 

 

 

 

 

Through the Wall

1

175 (53.3)

10 (3.1)

 

 

 

 

Through the Wall

2

170 (51.8)

10 (3.1)

 

 

 

 

Through the Wall

3

165 (50.3)

10 (3.1)

 

 

 

 

Through the Wall

4

160 (48.8)

10 (3.1)

 

 

 

 

Through the Wall

5

155 (47.2)

10 (3.1)

 

 

 

 

 

 

 

 

Through the Roof

0

180 (54.9)

15 (4.6)

 

 

 

 

Through the Roof

1

175 (53.3)

15 (4.6)

 

 

 

 

Through the Roof

2

170 (51.8)

15 (4.6)

 

 

 

 

Through the Roof

3

165 (50.3)

15 (4.6)

 

 

 

 

Through the Roof

4

160 (48.8)

15 (4.6)

 

 

 

 

Page 10

10

Bradford-White U2TW65T-FRN, UTW450S60FR-N, U1TW50S-FRN, UTW465S60FR-N, U1TW60T-FRN User Manual

Specifications

 

Control Timings

 

Ignition State

 

 

 

Timing

Pre-purge

15 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 34 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)

 

Wiring Diagram

 

 

BLOWER

 

 

BLOWER

 

BLOWER

 

 

 

TEMPERATURE

 

 

MOTOR

 

SWITCH

 

 

 

 

 

 

 

M

 

PRESSURE

G

 

BL

 

SWITCH W

 

Y

 

 

 

 

 

W

R

 

 

BK

Y

PILOT

G

 

 

 

W Honeywell

 

 

 

PLUG

BK

 

BKBK

 

G W RY

 

BK BL

WATER TEMPERATURE

 

SENSOR

RESETTABLE

FLAMMABLE

THERMAL

VAPOR SENSOR

Page 11

11

Sequence of Operation

Power Up Sequence

1.Start-up: Upon power up, the gas control runs a safe start check with a typical delay of 5 seconds.

2.Flammable Vapor Verification: 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

1.Thermostat Calls for Heat: Prior to energizing the blower, the gas control checks the safety circuit to insure the circuit is open. In the safety circuit the pressure switch is normally open and the blower temperature switch is normally closed.

2.If the safety circuit is closed, the gas control waits 4 seconds, the gas control LED flashes 2 times with a 3 second pause. The gas control waits 2 minutes. Then, the blower runs for 30 seconds. This cycle repeats until the safety circuit opens.

3.Blower energizes.

4.Pressure switch proves blower/vent system operation: If the pressure switch does not close within 30 seconds, the gas 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.

5.Blower pre-purge period (15 seconds).

6.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 blower will post-purge, and the gas control LED flashes 6 times with a 3 second pause.

Page 12

12

Sequence of Operation

Normal Heating Sequence (cont’d)

7.Main Burner Ignition: After pilot flame is sensed, the gas control activates the main valve for main burner ignition. The gas control will ignore flame and pressure switch signals for 3 seconds to allow for the main burner to stabilize.

8.Steady State Operation: During steady state operation, the gas control monitors:

Thermostat Temperature Sensor: When the setpoint temperature is satisfied, the gas control is shutdown, and the blower will post-purge for 15 seconds. The gas control LED flashes a short flash once every 4 seconds (Idle status code).

Pressure switch/blower temperature switch: If either switch opens, the pilot valve and the main valve are shut down. The blower continues to run for 30 seconds attempting to close the circuit. The gas control LED flashes 3 times with 3 second pause.

Flame Sensor: If flame is lost, the pilot and main valves are shutdown. The blower runs for 15 seconds. The gas control attempts to re-light the pilot 4 times. If unsuccessful, the blower is shutdown, 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.

9.Thermostat Satisfies: Gas control LED flashes once every 4 seconds. 10.Burner Off.

11.Blower post-purge (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 three second pause. This process is repeated 5 times until the control either returns to normal operation or proceeds to flammable vapor lockout.

Page 13

13

Sequence of Operation

Abnormal Operation (cont’d)

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 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 Open Circuit: The gas control immediately turns off all outputs and proceeds to flash 8 times then 3 times with a 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 3 times with three second pause. The error self clears if the fault clears for at least 15 seconds.

C)Water Temperature in excess of ECO (Energy Cut Off) Limit: The gas control immediately turns off the pilot and main valves. The gas control LED 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.Pressure Switch/Blower Temperature Fault:

A)Pressure switch closed at start of call for heat: The gas control waits 4 seconds then, proceeds to flash 2 times with a 3 second pause. The gas control waits 2 minutes and then turns on the blower for 30 seconds. The blower turns off after 30 seconds and the control waits for the pressure switch to open. Any time the pressure switch opens, the blower turns on (or stays on) and the control proceeds to wait for the pressure switch to close.

Page 14

14

Sequence of Operation

Abnormal Operation (cont’d)

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 the 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 a 3 second pause. The gas control waits 2 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 operation: The gas control turns off the pilot and main valve, runs the blower for 15 seconds (inter-purge) waiting for the pressure switch and/or the blower temperature switch to close. If either switch fails to close, the gas 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 a 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 the 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 a 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 spark igniter turns off, the pilot valve is closed. The gas control LED flashes 6 times then 1 time with 3 second pause. The control waits 5 minutes before repeating the ignition sequence.

Page 15

15

Sequence of Operation

Abnormal Operation (cont’d)

5.Flame Sensing Fault:

A)Flame Lost During Run: The gas control turns off the pilot and main valves and runs the 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 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 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 a 3 second pause. The control waits 5 minutes before repeating the ignition sequence.

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