Bradford White S-DW2-TW-75T6BN User Manual
EcoStor2
Gas Water Heaters
™
SERVICE
MANUAL
SUPPLEMENT
Solar
Troubleshooting Guide
SDW275S6BN shown above
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
Manual 238-48244-00A 11/09
Save this manual for future reference
2
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
3
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.
EcoStor2™ Solar
Solar Model Base Model
SDW4U5036FRN U45036FRN
SDW2504T6F(BN,SX) M2XR504T6F(BN,SX)
SDW2TW50T6F(BN,SX) M2TW50T6F(BN,SX)
SDW2U65T6FRN U2XR65T6FRN
SDW265T6F(BN,SX) M2XR65T6F(BN,SX)
SDW2TW65T6F(BN,SX) M2TW65T6F(BN,SX)
SDW275S6(BN,SX) M2XR75S6(BN,SX)
SDW2TW75T6(BN,SX) M2TW75T6(BN,SX)
Service Manual
238-47132-00
238-44923-00
238-46238-00
238-47132-00
238-44943-00
238-46238-00
238-46647-00
238-47150-00
How to use this Manual
3
4
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.
EcoStor2™ Solar
Introduction
4
5
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.
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.
EcoStor2™ Solar
Thermistor Wiring
Brown and Orange twisted
thermistor wires
Upper Access Location
(Orange Twisted Pair)
Lower Access Location
(Brown Twisted Pair)
5
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