Bradford-White UDH75T50FR'N User Manual

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UDS / UDH Series

Ultra Low NOx Direct Vent Water Heaters

SERVICE

MANUAL

Troubleshooting Guide and Instructions for Service

(To be performed ONLY by qualified service providers)

Models Covered

by This Manual:

ECO-DefenderSafety System® Models

UDS140S*FRN

UDS150S*FRN

UDH1504T*FRN

UDH165T*FRN

UDH175S*FRN

UDH50T45FR*N

UDH65T45FR*N

UDH75T50FR*N

(*) Denotes Warranty Years

Manual 238-49640-00A

Save this manual for future reference

The Bradford White

Ultra Low NOx Direct Vent Water Heaters

Table of Contents

 

Page

 

Service Procedure

Introduction

 

3

 

- - -

Trouble shooting Chart

4

- - -

Inner Door Gasket Removal, Inspection, Replacement and Installation

6

 

I

Thermopile Testing and Replacement

9

 

II

Pilot Assembly Inspection Cleaning and Replacement

10

 

III

Igniter, Electrode Testing and Replacement

11

 

IV

Honeywell Gas Control Testing, Disassembly, and Replacement

20

 

V

Burner Operation Inspection, Adjustment, Cleaning and Replacement

21

 

VI

Dip Tube and Anode Inspection and Replacement

23

 

VII

Generic Parts List

25

- - -

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2

INTRODUCTION

The new Bradford White UDS and UDH water heaters are designed to provide reliable performance with enhanced standard features. Design features include reliable standing pilot ignition system, enhanced diagnostics, simplified servicing, certified FVIR technology and Ultra Low NOx emissions.

The UDS and UDH water heaters use a combustion system where combustion air is drawn from the outside of the building. The gas control maintains water temperature and maintains gas flow. If a situation outside of normal operating parameters exists, the gas control diagnostic LED wll 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 gas valve can be removed and replaced without draining the water heater.

Please read the service manual completely before attempting service on this new series of direct vent water heaters.

How the Safety System Works

During normal operation, air for the combustion chamber is drawn into the water heater through the vent pipe from outside your building. The air travels into the closed combustion chamber. The air then mixes in a normal manner with supplied gas and is efficiently combusted, producing Ultra Low NOx emissions.

In the unlikely event trace amounts of flammable vapors are present in the area surrounding the water heater, the sealed combustion system prevents the flammable vapors from reaching the ignition source.

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Honeywell Gas Control Troubleshooting Chart

Flammable Vapor Ignition Resistant Water

Heaters

Observe green LED indicator on 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.

LED Status

Control Status

None (LED not on or

Pilot assembly is not lit

flashing

 

Green LED Indicator

Probable Cause

Service

Procedure

If the pilot will not stay

. lit replace pilot

Gas Control is not powered. Light pilot. assembly. If problem persists replace Gas Control.

One flash and three second pause

1.If set point knob is in “PILOT” position then pilot flame is detected. Turn set point knob to desired setting.

2.If the set point knob is already at the desired setting, the water heater is satisfied.

1.Gas Control is powered and waiting for the set point knob to be turned to a water temperature setting.

2.Water heater is satisfied and operating normally.

1. Adjust set point knob to desired setting.

Two quick flashes and a three second pause

LED on continuously (Solid)

Two flashes and three second pause

Four flashes and three second pause

Gas control is calling for heat (no fault).

Set point knob has been recently turned to the “OFF” position. Wait until LED goes out before attempting to relight

Weak pilot signal detected. System will reset when pilot flame is sufficient.

Excessive tank temperature. System must be reset.

Tank temperature below set point of thermostat.

Set point knob was turned to “OFF” position.

1.Thermopile failure

2.Unstable pilot

3.Pilot tube block or restricted.

1.Temperature sensor out of calibration

2.Faulty Gas Control

Normal operation.

LED will go out and the control will function normally when the pilot is lit.

1.See service procedure II

2.See service procedure III

3.See service procedure III

1.See service procedure V

2.See service procedure V

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4

Honeywell Gas Control Troubleshooting Chart

Flammable Vapor Ignition Resistant Water

Heaters

Observe green LED indicator on 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

LED Status

Control Status

Probable Cause

Service

Procedure

 

 

 

Five flashes and three second pause

Six flashes and three second pause

Seven flashes and three second pause

Eight flashes and three second pause

Thermostat/well sensor fault.

Water leak detected by accessory module.

Gas Control electronic fault detected.

Standing pilot remains on while set point knob is in “OFF” position.

1.Damage to the temperature sensor.

2.Temperature sensor resistance out of range.

Excessive amount of water in drain pan/water dam.

1.Control needs to be reset.

2.Control is wet or physically damaged.

Pilot valve stuck in open position.

1. See service procedure V

1.Check T&P valve

2.Check all water fittings.

3.Pressurize and leak test tank.

1.Reset Gas Control

2.Replace Gas Control.

Replace Gas Control.

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5

The Bradford White

SERVICE PROCEDURE I

Inner Door/Gasket Removal, Inspection

Replacement and Reinstallation

Inner Door Removal Procedure

Step 1. Rotate set point knob of the gas control to the “OFF” position.

Step 2. Turn off the gas supply to the water heater

Step 3. Remove the outer door.

Step 4. Remove the four (4) ¼” hex drive screws holding the right side inner door in place

Step 5. Remove the three (3) ¼” hex drive screws holding the left side burner door in place.

¼” Hex Drive Screws at Flange Area of Inner Door

¼” Hex Drive Screws on Left Side Inner Door

Step 6. Disconnect the pilot tube from the gas control using a 7/16" wrench. Remove the main burner feedline from the gas control with a ¾” wrench.

Step 7. Disconnect the spark igniter wire from the gas control.

Step 8. Remove the burner assembly from the combustion chamber.

¼” Hex Drive Screws Right Side Inner Door

Step 9. Fully inspect burner and inner door gaskets for the following:

>Tears

>Other imperfections that will inhibit proper seal

>Missing Material

>Gasket adhesion to inner door

>Cracks

>Material left on combustion chamber (around opening)

>Dirt or debris

 

If the gasket is not affected by any of the above, gasket replacement is not required. If replacement is required, proceed to Inner Door Gasket Replacement Procedure.

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6

The Bradford White

SERVICE PROCEDURE I

 

Inner Door/Gasket Removal, Inspection

 

Replacement and Reinstallation

Inner Door Gasket Replacement Procedure.

WARNING

If the information in these instructions is not followed exactly, a fire or explosion may result causing property damage, personal injury or death.

Step 10. After inspection of inner door as noted in step 9, completely remove gasket and adhesive residue from burner and left side inner doors as needed.

Step 11. Use RTV sealant (recommended bead size 1/8") to secure the inner door gasket to the inner door sections (right & burner). The burner door gasket must be sliced in the location shown on the illustration below in order to slide the gasket over the burner venturi. Refer to illustration below for proper RTV sealant application. Note the overlap configuration in the flange area of the inner door. Set the flange section first, this will help to achieve the proper over lap position.

Installation of Inner Door With

Gasket.

Step 12. Clean any residual gasket residue or other debris from combustion chamber surface before installing the inner door/gasket assembly.

Step 13. Place the burner door into position first. Tighten the pilot line nut to the gas control. Tighten the

main burner feedline to the gas control. Use the ¼” hex drive screw without the built-inwasher to secure the right side of the burner door to the chamber. Use the ¼” hex drive screws with thebuilt-inwasher to secure the left side of the burner door in place.DO NOT OVER

TIGHTEN SCREWS.

Step 14. Position the fiberglass sock containing the igniter wire, the pilot tube and the armored thermopile cable against the inner door flange.

WARNING

Stripped fastener connections may allow for seal breach of inner door. A seal breach may result in a fire or explosion causing property damage, personal injury or death. Do not over tighten screws in steps 13, 15 and 16.

If a fastener connection is stripped, contact the manufacturer listed on the water heater rating plate.

Page 37

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7

The Bradford White

SERVICE PROCEDURE I

Inner Door/Gasket Removal, Inspection

Replacement and Reinstallation

Position fiberglass sock, pilot tube and armored thermopile cable against flange.

Step 15. Firmly place right side inner door flange against the burner door flange and secure with two ¼” drive screws from step 5. DO NOT OVER TIGHTEN SCREWS.

Step 16. Align right side inner door to combustion chamber and verify the fastener holes of the combustion chamber are aligned with the right side inner door slotted opening. Verify seal integrity around combustion

opening. Secure right side inner door using 1/4” hex drive screws from step 5. DO NOT OVER TIGHTEN SCREWS. Verify both burner and right sides of the inner door are properly positioned and sealed against

the combustion chamber.

Secure flange with ¼" drive screws.

Verify threaded hole alignment with slotted openings in inner door.

Step 17. Reconnect the igniter wire to the gas control

Step 18. Replace outer jacket burner access door.

Step 19. To resume operation follow the instructions located on the lighting instruction label or the lighting instructions located in the installation and operation manual.

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The Bradford White

SERVICE PROCEDURE II

Thermopile Testing and Replacement

OPEN CIRCUIT THERMOPILE TESTING

The following test should be performed while the pilot flame is on.

Step 1. Turn knob to pilot position and depress.

Step 2. Continue pressing knob and remove red (+) thermopile wire from the red wire leading from the gas control. Also remove white (-)thermopile wire from the gas control.

Step 3. Using a multimeter capable of measuring millivolts, connect the positive side of the multimeter to the red (+) thermopile wire connector. Connect the negative side of the multimeter to the white thermopile connector.

White (-)thermopile wire

Red (+) thermopile wire

Red gas control wire

Red (+) thermopile wire

White (-)thermopile wire

Normal thermopile operation will be between 350mV - 850mV. If reading is less than 350mV, replacement of pilot assembly is recommended following SERVICE PROCEDURE III.

Step 4. If thermopile reading is between 350mV - 850mV, remove multimeter and reconnect red (+) thermopile wire to red wire leading from the gas control. Reconnect white (-)thermopile wire negative(-)terminal on gas control.

Step 5. Release Gas Control knob and turn to desired setting to resume normal operation.

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The Bradford White

SERVICE PROCEDURE III

Pilot Assembly Inspection, Cleaning

and Replacement

PILOT/ELECTRODE ASSEMBLY INSPECTION,

CLEANING AND REPLACEMENT

Step 1. Turn off gas supply to water heater. Rotate knob of gas control/gas valve

to “OFF” position.

For Honeywell Control, rotate knob counter-clockwiseto the “OFF” position.

Thermopile connections

Pilot tube

Step 2. Remove outer jacket door.

Step 3. Remove burner and right side inner door per

SERVICE PROCEDURE I, steps 1 through 8.

Step 4 Disconnect thermopile, pilot tube, and feedline from gas control.

Step 5 Disconnect igniter wire from gas control.

Step 6.

Remove pilot/electrode assembly from burner (¼”

Feedline nut

 

drive tool).

Igniter wire

Step 7. Inspect pilot for the following:

a)Primary air openings for blockage. Must be free from any debris (dirt, lint, etc).

b)Kinks or cracks in the pilot tube. If found,

the pilot must be replaced.

Step 8. Inspect pilot orifice:

Primary air opening

a)Remove ½" nut from bottom of pilot assembly.

b)Remove pilot tube and pilot orifice.

c)Inspect pilot orifice for blockage, must be cleaned or replaced. (Honeywell pilot orifice not replaceable, replace pilot assembly)

Step 9.

Install pilot/electrode assembly to feedline, secure with screw from step 6.

 

Step 10.

Re-Installburner assembly and right side inner door per SERVICE

Pilot orifice

 

PROCEDURE I, steps 9 through 19.

 

Step 11.

To resume operation follow the instructions located on the lighting instruction label or the lighting instructions

 

located in the installation and operation manual.

 

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