Bradford White S-DW2-TW-75T6BN - Manual (Page 4)

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