Bradford-White ECOSTOR2 SDW2TW50T User Manual

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E

tor2Solar

Ga

Water Heate

S ICE

MANUAL

S

T eshooting Guide a structions for Service

(To be performed ONLY by

qua

ce providers)

M

Covered

by This Manual:

SDW250

SDW265

SDW275S*(BN,SX)

SDW2TW50T*F(BN,SX)

SDW2TW65T*F(BN,SX)

SDW2TW75T*(BN,SX)

(*) Denotes Warra y Years

SDW

n above

M

l 238-4

Save this manual for future reference

The Bradford White

EcoStor2™ Solar

Gas Water Heaters

Table of Contents

 

Page

Service Procedure

How to use this manual

3

- - -

Introduction

4

- - -

Thermistor Wiring

5

- - -

Thermistor Wiring Test Procedure

6

ST-I

Gas Control Temperature Sensor

7

- - -

Temperature Sensor and Harness Testing

8

ST-II

Temperature Sensor Measurement

9

ST-III

Solar Thermal Troubleshooting

10

- - -

Solar Thermal Parts List (Atmospheric)

11

- - -

Solar Thermal Parts List (Ultra Low NOx)

12

- - -

Solar Thermal Parts List (TTW)

13

- - -

Notes

14

- - -

2

2

EcoStor2™ Solar

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 EcoStor2™ Solar with Gas Backup Water Heaters. Understanding the solar thermal sequence of operation section of this manual will contribute greatly to troubleshooting the water heater.

This manual serves as a water heater supplement to service and troubleshoot specifically the solar features of the water heater. Please refer to the table below to determine which base model service manual is appropriate for the non-solarfeatures of the water heater.

Solar Model

Base Model

Service Manual

SDW4U5036FRN

U45036FRN

238-47132-00

 

 

 

SDW2504T6F(BN,SX)

M2XR504T6F(BN,SX)

238-44923-00

 

 

 

SDW2TW50T6F(BN,SX)

M2TW50T6F(BN,SX)

238-46238-00

 

 

 

SDW2U65T6FRN

U2XR65T6FRN

238-47132-00

 

 

 

SDW265T6F(BN,SX)

M2XR65T6F(BN,SX)

238-44943-00

 

 

 

SDW2TW65T6F(BN,SX)

M2TW65T6F(BN,SX)

238-46238-00

 

 

 

SDW275S6(BN,SX)

M2XR75S6(BN,SX)

238-46647-00

 

 

 

SDW2TW75T6(BN,SX)

M2TW75T6(BN,SX)

238-47150-00

 

 

 

3

3

EcoStor2™ Solar

Introduction

The Bradford White EcoStor2 Solar Water Heater System

The new Bradford White Solar with Gas Backup water heaters are designed to provide reliable performance with enhanced standard features. New design features include an internal double-wall,atmospherically vented heat exchanger for safe and effective heat transfer, a gas control temperature sensor in the upper portion of the water heater to maximize solar efficiency and thermistor wires to allow seamless connection to a solar controller.

Double-wall Heat Exchanger—Anatmospherically venteddouble-wallheat exchanger allows an internal heat exchanger to safely use a propylene glycol/water mix commonly applied in solar thermal heating systems. In the unlikely event that either wall of the heat exchanger leaks, the fluid will follow a vent path to exit the water heater through the heat exchanger fitting. This fluid will run down the outside of the water heater to indicate a leak to the home owner.

Having an immersed heat exchanger enhances heat transfer, being able to heat directly to the potable water.

Gas Control Temperature Sensor—Atemperature sensor located in the upper portion of the water heater allows the solar thermal system to maximize the solar collector efficiency. This is due to the potential low temperatures observed in the tank bottom where the immersed heat exchanger is located. The gas backup will only heat the water when the solar thermal system is not producing enough heat to keep the gas control temperature sensor at the temperature level indicated on the gas control, thereby requiring the backup heat.

Thermistor Wiring—Thermistorwiring is provided to allow thermistor connection to the solar thermal control without running wires outside the water heater. Thermistors are not included due to multiple thermistor possibilities with the various solar thermal controls that may be installedon-site.There are 2 pair of wires provided; one in the lower portion of the tank to allow the temperature difference to be read between the water heater and the solar collector, and a second in the upper portion of the water heater to allow a solar control to read the expected delivered temperature.

This service manual supplement 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. 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 supplement completely before attempting service on this new series of solar thermal models.

4

4

EcoStor2™ Solar

Thermistor Wiring

This section is intended to provide a better understanding of the solar thermal design application and how it varies from the base model listed on page 3.

Solar Thermistor Wiring

The solar with gas backup water heater comes provided with two sets of twisted thermistor wiring. They are color coded for ease of use.

Brown and Orange twisted thermistor wires

The solar with gas backup models come with an internal double-wallheat exchanger.

Brown thermistor wiring is provided under an access panel between the solar heat exchanger connections. A thermistor (not included) wired to this pair can be connected to the solar control to determine the temperature differential between the tank and the solar collector. The control can then activate a circulator to heat the tank. To assist in connecting the thermistor, the end has a supplied wire nut. A bracket and plate is supplied to mechanically press the thermistor against the tank wall.

A twisted orange wire set is provided under the upper access panel. Some solar controllers have locations for a second tank temperature input. This is not used for controlling the solar thermal system, but helps the end user understand what an anticipated delivered temperature may be.

Upper Access Location

Lower Access Location

(Orange Twisted Pair)

(Brown Twisted Pair)

5

5

EcoStor2™ Solar

ST-IThermistor Wiring

Test Procedure

Thermistor Wire Testing

Step 1. Disconnect and unplug the solar control.

Step 2. Disconnect the thermistor twisted pair from the control or control sensor wiring.

Step 3. Connect a multimeter set to read ohms to the twisted wire stripped ends.

Determine the resistance value of the attached thermistor. NOTE: The thermistor is field supplied and various

thermistors have different ohm values for different temperatures. Refer to the temperature specification sheet for the thermistor installed on the water heater to determine if the resistance value is correct.

The image to the side shows a resistance value for a thermistor at ambient temperature connected under the lower access cover (brown twisted pair). The same procedure can be followed to determine if the upper thermistor value is correct.

Step 4. If the multimeter indicates a resistance that does not match the actual temperature of the thermistor, replace the thermistor. Reconnect the wiring, verify that the new thermistor does match, and reconnect to the solar control. Turn on the power to the solar control.

If the multimeter indicates a short or open, disconnect the thermistor from the connection made under the access cover. Measure the thermistor ohm value directly. If the multimeter indicates an open, replace the thermistor.

If the multimeter indicates an appropriate ohm value, determine which wire is open by measuring directly from one end of the wire to the other, or if short; verify by measuring both wire ends from the same location. If the wiring cannot be fixed, the wiring for the thermistor may have to be ran on the outside of the water heater. Replace the wiring, and reconnect it to the solar control. Turn on the power to the solar control.

6

6

EcoStor2™ Solar

Gas Control

Temperature Sensor

The solar with gas backup water heater senses temperature from the upper portion of the tank. This allows the solar thermal heating system to maximize the ability to heat the water inside the tank. Only when the upper portion of the water heater tank reaches the water temperature to turn on the gas control, does the backup heat begin. This is achieved by placing a thermistor sensor inside a thermal well and connecting the sensor by means of a wire harness to the gas control. The thermistor well, sensor and wire harness connection is located under the top access cover.

Thermistor sensor

Thermistor sensor

Wire harness

in well

outside well

connection to

 

 

thermistor

Wire harness connected

Wire harness plug in

to the gas control

location to the gas control

 

NOTE: Depending on the solar with gas backup model, the gas control may vary. Refer to the base model service manual as indicated on page 3.

7

7

EcoStor2™ Solar

ST-IITemperature Sensor

and Harness Testing

If the control has gone into lockout due to excessive tank temperature (four flash, 3 second pause) reset the control by rotating the gas control knob to “OFF” position. Then follow the lighting instructions and return the gas control knob to the desired setpoint.

Observe the water heater operation. If the gas control continues to lockout due to excessive tank temperature, proceed to thermal sensor and harness testing to determine the cause.

Disconnect thermal well wire harness

THERMAL SENSOR AND

HARNESS TESTING Position the gas control knob to the “OFF” position and disconnect the thermal sensor harness from the gas control.

Using a multi-meterset to the Ohms setting, determine the resistance of thermal sensor .

(see caution photos at right)

CAUTION

DO NOT use standard multimeter probes for this test. Doing so will damage connector. Use special pin type electronic probes or small diameter wire pins inserted into connector.

Using a multi-meterset to the ohms setting, insert one meter probe (see caution) into center wire position of thermal well connector, insert the second probe (see caution) into either of the outside wire positions (see photo on left).

Alternate the probe on the outside position to the opposite outside wire position (see photo on right).

Once the thermal sensor resistance values are

N

Repeat Ohm measurement at the

 

known, the water temperature must also be known

 

sensor connector.

to determine if the resistance values are correct.

 

Are thermal sensor resistance

See page 9 to obtain water temperature.

 

 

values correct?

 

 

Are thermal sensor and harness resistance values correct?

Y

Replace gas control

N

Y

Replace sensor

Replace thermal

wire harness

well sensor

8

8

EcoStor2™ Solar

ST-IIITemperature Sensor

Measurement

WARNING

Stored water may be HOT when performing the following steps in this procedure. Take necessary precaution to prevent personal injury.

DETERMINE THE WATER TEMPERATURE INSIDE THE STORAGE TANK

NOTICE

It is important to understand once the resistance for the temperature sensor is determined from the previous page, water flow through the water heater should not occur. Prior to drawing water from drain valve, turn off the cold water supply to the water heater. This will prevent cold water flow into the tank affecting the resistance value of the temperature sensor.

Step 1. Set the Gas Control knob to the “OFF” position.

Step 2. Turn off inlet water supply to water heater.

Step 3. Draw approximately 4 gallons of water from drain valve into a container, or suitable drain, and discard. Draw an additional gallon and immediately measure water temperature using an accurate thermometer. It may be necessary to open a hot water faucet to allow water heater to drain.

Step 4. Using the chart below, determine correct resistance value for the water temperature from step 3.

Example: If the temperature of the water is 84°F, then the resistance through the sensor would be 8449 (see shaded area). NOTE: Sensor resistance increases as the temperature decreases.

In Degrees F

°F

0

1

2

3

4

5

6

7

8

9

40

26109

25400

24712

24045

23399

22771

22163

21573

21000

20445

50

19906

19383

18876

18383

17905

17440

16990

16553

16128

15715

60

15314

14925

14548

14180

13823

13477

13140

12812

12494

12185

70

11884

11592

11308

11032

10763

10502

10248

10000

9760

9526

80

9299

9078

8862

8653

8449

8250

8057

7869

7685

7507

90

7333

7165

7000

6839

6683

6531

6383

6238

6098

5961

100

5827

5697

5570

5446

5326

5208

5094

4982

4873

4767

110

4663

4562

4464

4368

4274

4183

4094

4006

3922

3839

120

3758

3679

3602

3527

3453

3382

3312

3244

3177

3112

130

3048

2986

2925

2866

2808

2752

2697

2643

2590

2538

140

2488

2439

2391

2344

2298

2253

2209

2166

2124

2083

150

2043

2004

1966

1928

1891

1856

1820

1786

1753

1720

160

1688

1656

1625

1595

1566

1537

1509

1481

1454

1427

170

1402

1376

1351

1327

1303

1280

1257

1235

1213

1191

180

1170

1150

1129

1110

1090

1071

1953

1035

1017

999

190

982

965

949

933

917

901

886

871

857

842

200

828

814

801

788

775

762

749

737

725

713

9

9

EcoStor2™ Solar

Solar Thermal

Troubleshooting Chart

This troubleshooting chart serves as a water heater supplement to troubleshoot specifically the solar features of the water heater. Please refer to page 3 to determine which base model service manual is appropriate for the non-solartroubleshooting chart for the water heater.

 

 

 

 

 

SERVICE

SYMPTOM

PROBABLE CAUSE

CORRECTIVE ACTION

PROCEDURE

 

1.

Gas control

1.

Verify accurate

 

 

 

temperature is sensed.

 

 

 

temperature sensor

2.

 

 

 

Review calculations to

 

 

 

out of spec.

 

 

2.

Improperly sized

 

determine appropriate

 

Not enough

 

solar collector(s).

3.

collectror array.

1. See service

hot water

3.

Gas backup not

Review service manual

procedure ST-II.

 

 

functioning.

4.

for base model.

 

 

4.

Solar thermal

Review solar thermal

 

 

 

system not

 

system for

 

 

 

functioning.

 

functionality.

 

10

10