13
Explanation of Major Components and Their
Function.
COLLECTOR:
The SunEarth collectors in your SUN HoM system
are flat plate type. They are designed to maximize
the capture of solar energy in the temperature
ranges required for domestic hot water. Flat plate
collectors accomplish this by employing the green
house effect. The glass covering permits up to 90%
of the visible sunlight to enter the collector. When
the light passes through the glass it’s frequency is
changed slightly to a lower energy level. When the
light strikes the absorbing surface of the flat plate
inside the light is absorbed as heat. The
combination of the glass frequency change and the
solar absorbing surface of the plate capture the
maximum amount of energy. As the absorber plate
heats up it begins to radiate energy as infrared (IR)
or heat radiation. Glass is essentially opaque to IR
wavelengths so the heat is trapped increasing the
temperature.
TANK SYSTEM ASSEMBLY:
Unlike most other solar systems your SUN HoM
Drainback system comes pre plumbed and wired as
a complete assembly. This is called the Tank
System Assembly or TSA. The TSA contains the
water heater tank, the heat exchanger, pump
controller, drainback tank, tank sensor, drain valve,
system drain valve and the wiring and piping to
make all connections. The TSA, the collectors and
the interconnect piping make up the complete
system.
TANK SYSTEM ASSEMBLY: (cont.)
•
Pump: The system is equipped with a single
TACO 009 or 008 Bronze circulator pump. It
uses 115V regular AC power which is supplied
from the controller. When heat is available in
the collector the pump is energized to lift the
heat transfer fluid (distilled water) through the
interconnect piping to the collectors where it
gains heat. The water then returns to the
drainback tank, then to the heat exchanger
where it heats the potable water. The cycle
continues until the collector can no longer
contribute heat energy.
•
Controller: The controller is powered by 115V
house current and is the device that determines
if solar energy is available. The controller,
through the sensors, constantly measures the
temperature of the water heater tank and the
collector, comparing them to see if the collector
is hotter then the tank. When the collector
reaches a 12
0
F higher temperature than the
water heater tank the controller energizes the
pump. As stated above the pump will continue
to run until the differential temperature (the
difference between the collector and the tank)
drops to 4
0
F. When this happens the pump is
turned off and the heat transfer fluid drains back
into the drainback tank.
•
Sensors: The system contains 2 sensors, one
at the outlet of the collector and one on the
bottom of the water heater tank. The controller
uses these 2 sensors to measure tank and
collector temperatures. They are simple
thermistor (thermal resistors) type sensors that
have an inverse reaction to temperature. As the
temperature goes, up the resistance goes
down. The controller is calibrated to read this as
temperature changes. As the collector heats up
the resistance goes down and at the right point
the controller turns on the pump. The reverse
happens when the collector cools off.
•
Water Heater Tank: This is standard glass lined
steel tank that is constructed just like any other
water heater. The only difference is that it has a
heat exchanger wrapped around the outer steel
or it has extra ports to make connections to. In
the DBHE series systems the heat exchanger is
a copper coil wrapped around the lower half of
the tank before it is insulated. In the DBSA
series, the tank has side ports and the heat
exchanger is external to the tank. In either
system the heat exchanger is used to transfer
solar heat energy to the potable water.
•
Heat Exchanger: An all copper device used to
transfer solar heat to the potable water. See
“System Start Up” section above for more detail
on how this works.
•
Temperature and Pressure Relief Valve: This
device is inserted into the water heater tank for
safety. It is located on top of the tank. The T&P
relief valve is preset to open and discharge if
either a high pressure or high temperature
situation occurs in the water heater. All water
heaters regardless of whether they are solar
power or not, must have this safety device
which is required by national building codes.
There is no T&P valve required in the collector
loop as it is a non-pressurized type.
•
Isolation Valve: Also called “Shut Off Valve”,
this valve is installed in the cold water service
13
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