EcoStor2™ Solar
Gas Water Heaters
SERVICE
MANUAL
SUPPLEMENT
Troubleshooting Guide
and Instructions for Service
(To be performed ONLY by
qualified service providers)
Models Covered
by This Manual:
SDW2504T*F(BN,SX)
SDW265T*F(BN,SX)
SDW275S*(BN,SX)
SDW2TW50T*F(BN,SX)
SDW2TW65T*F(BN,SX)
SDW2TW75T*(BN,SX)
(*) Denotes Warranty Years
SDW275S6BN shown above
Manual 238-48244-00A 11/09
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How to use this Manual
EcoStor2™ Solar
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-solar
features of the water heater.
Solar Model
SDW4U5036FRN
Base Model Service Manual
U45036FRN
238-47132-00
238-44923-00
238-46238-00
238-47132-00
238-44943-00
238-46238-00
238-46647-00
238-47150-00
SDW2504T6F(BN,SX)
SDW2TW50T6F(BN,SX)
SDW2U65T6FRN
M2XR504T6F(BN,SX)
M2TW50T6F(BN,SX)
U2XR65T6FRN
SDW265T6F(BN,SX)
SDW2TW65T6F(BN,SX)
SDW275S6(BN,SX)
SDW2TW75T6(BN,SX)
M2XR65T6F(BN,SX)
M2TW65T6F(BN,SX)
M2XR75S6(BN,SX)
M2TW75T6(BN,SX)
3
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Introduction
EcoStor2™ Solar
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—An atmospherically vented double-wall heat
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—A temperature 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—Thermistor wiring 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 installed on-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
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Thermistor Wiring
EcoStor2™ Solar
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-wall heat 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
(Orange Twisted Pair)
Lower Access Location
(Brown Twisted Pair)
5
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ST-I
Thermistor Wiring
Test Procedure
EcoStor2™ Solar
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
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Gas Control
Temperature Sensor
EcoStor2™ Solar
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.
Wire harness
connection to
thermistor
Thermistor sensor
in well
Thermistor sensor
outside well
Wire harness connected
to the gas control
Wire harness plug in
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
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ST-II
Temperature Sensor
and Harness Testing
EcoStor2™ Solar
Disconnect thermal
well wire harness
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.
THERMAL SENSOR AND
HARNESS TESTING
Position the gas control knob to the
“OFF” position and disconnect the
thermal sensor harness from the gas
control.
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-meter set to the
Using a multi-meter set 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).
Ohms setting, determine the
resistance of thermal sensor .
(see caution photos at right)
Alternate the probe on the outside position to the opposite outside wire position
(see photo on right).
N
Repeat Ohm measurement at the
sensor connector.
Once the thermal sensor resistance values are
known, the water temperature must also be known
to determine if the resistance values are correct.
See page 9 to obtain water temperature.
Are thermal sensor resistance
values correct?
Are thermal sensor and harness
resistance values correct?
N
Y
Replace sensor
wire harness
Replace thermal
well sensor
Y
Replace gas
control
8
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ST-III Temperature Sensor
Measurement
EcoStor2™ Solar
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 draw-
ing 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
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
0
1
2
3
4
5
6
7
8
9
26109
19906
15314
11884
9299
7333
5827
4663
3758
3048
2488
2043
1688
1402
1170
982
25400
19383
14925
11592
9078
7165
5697
4562
3679
2986
2439
2004
1656
1376
1150
965
24712
18876
14548
11308
8862
7000
5570
4464
3602
2925
2391
1966
1625
1351
1129
949
24045
18383
14180
11032
8653
6839
5446
4368
3527
2866
2344
1928
1595
1327
1110
933
23399
17905
13823
10763
8449
6683
5326
4274
3453
2808
2298
1891
1566
1303
1090
917
22771
17440
13477
10502
8250
6531
5208
4183
3382
2752
2253
1856
1537
1280
1071
901
22163
16990
13140
10248
8057
6383
5094
4094
3312
2697
2209
1820
1509
1257
1953
886
21573
16553
12812
10000
7869
6238
4982
4006
3244
2643
2166
1786
1481
1235
1035
871
21000
16128
12494
9760
7685
6098
4873
3922
3177
2590
2124
1753
1454
1213
1017
857
20445
15715
12185
9526
7507
5961
4767
3839
3112
2538
2083
1720
1427
1191
999
842
713
828
814
801
788
775
762
749
737
725
9
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Solar Thermal
EcoStor2™ Solar
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-solar troubleshooting
chart for the water heater.
SERVICE
PROCEDURE
SYMPTOM PROBABLE CAUSE CORRECTIVE ACTION
1. Verify accurate
1. Gas control
temperature is sensed.
temperature sensor
2. Review calculations to
determine appropriate
collectror array.
out of spec.
2. Improperly sized
solar collector(s).
3. Gas backup not
functioning.
Not enough
hot water
1. See service
procedure ST-II.
3. Review service manual
for base model.
4. Solar thermal
system not
4. Review solar thermal
system for
functioning.
functionality.
10
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Solar Thermal Parts List
(Atmospheric)
EcoStor2™ Solar
1
2
3
4
5
6
7
8
9
Draft Hood
Hex Head Anode Aluminum
Heat Trap Insert
Hot Water Outlet Anode Aluminum
Cold Water Inlet Polysulfone (NC Code)
Flue Baffle Complete
Junction Box Cover
Conduit Cover/Ground
T&P Relief Valve
10 Thermostat Bracket Assembly
11 Access Cover
12 Outer Door
13 Screw-#6-20 x 3/8 PHCR
14 Nat. Gas Resettable Thermal Switch
15 Nat. Gas Right Side Inner Door Complete
16 Screw-#8-18 x 3/4 HWH
17 Left Side Inner Door Complete
18 Screw-#10-12 x 3/4 HWH
19 Brass Drain Valve
Wire Harness (Gas Control to Resettable
Thermal Switch)
20
21 Gas Control Natural Gas (w/ Service Tool)
22 Gas Control Service Tool
23 Control Bracket
24 Thermostat Sensor
25 Thermostat Sensor Well
26 Inner Door Gasket Kit
27 ASSE Approved Mixing Valve (Optional)
28 Universal Integrated Mixing Device Kit (IMD)
29 Thermostat Sensor Wire Harness
30 Solar Sensor Wire Harness
31 Burner Assembly Complete
32 Burner
33 Main Burner Orifice
34 Pilot Assembly
35 Pilot Orifice
11
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Solar Thermal Parts List
(Ultra Low NOx)
EcoStor2™ Solar
1
2
3
4
5
6
7
8
9
Draft Diverter
Hex Head Anode (Aluminum)
Heat Trap Insert
Hot Water Outlet Anode (Aluminum)
Cold Water Inlet Polysulfone (NC Code)
Flue Baffle
Junction Box Cover
Conduit Cover/Ground
T&P Relief Valve
10 Thermostat Bracket Assembly
11 Access Cover
12 Screw-#8-18 X 3/4 HWH
13 Screw-#10-12 X 3/4 HWH
14 Right Side Inner Door Complete
15 Screw-#6-20 X 3/8 PHCR
16 RTD Sensor
17 Outer Door
18 Brass Drain Valve
Wire Harness (Gas Control to Resettable
Thermal Switch)
19
20 Gas Control (w/ Service Tool)
21 Gas Control Service Tool
22 Gas Control Bracket
23 Thermostat Sensor
24 Thermostat Sensor Well
25 Inner Door Gasket Kit
26 ASSE Approved Mixing Valve (Optional)
27 Universal Integrated Mixing Device Kit (IMD)
28 Burner Assembly
29 Manifold Mount
30 Orifice
31 Flexible Gas Feedline
32 Resettable Thermal Switch
33 Burner
36 Pilot Orifice
37 Thermopile Kit
34 Pilot Assembly Kit
38 Thermostat Sensor Wire Harness
39 Solar Sensor Wire Harness
35 Screw-#8-18 X 1/2 TEK
12
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Solar Thermal Parts List
(TTW)
EcoStor2™ Solar
1
2
3
4
5
6
7
8
9
Blower Complete
Air Mixing Inlet
Pressure Switch
Blower Temperature Switch
Blower Gasket
Blower Power Cord
3" Exhaust Adaptor w/Vent Terminal
Condensate Hose Kit (Optional)
Heat Trap Insert
10 Hot Water Outlet Aluminum
11 Flue Baffle
12 Hex Head Anode Aluminum
13 Cold Water Inlet
14 Safety Circuit Wire Harness
15 T&P Relief Valve
16 Outer Door
17 Right Side Inner Door Complete
18 Screw-#8-18 x 3/4 HWH
19 Left Side Inner Door Complete
20 Screw-#10-12 x 3/4 HWH
21 Brass Drain Valve
22 Flammable Vapor Sensor Clip
23 Flammable Vapor Sensor
Flammable Vapor Sensor Harness/
Simulated Resistive Device
24
25 Control Bracket
26 Gas Valve Natural Gas
27 Gas Valve Service Tool
28 Temperature Sensor Well
29 Temperature Sensor
30 Solar Sensor Bracket Assembly
31 Access Cover
32 Cover Junction Box
33 Cover Conduit/Ground
34 Inner Door Gasket Kit
39 Burner Assembly Complete
35 ASSE Approved Mixing Valve (Optional)
36 Universal Integrated Mixing Device Kit (IMD)
37 Thermostat Sensor Wire Harness
38 Solar Sensor Wire Harness
40 Burner
41 Main Burner Orifice
42 Pilot Assembly
43 Pilot Orifice
13
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NOTES
14
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NOTES
15
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