
Installation Manual
two tank systems the mixing valve may be located;
either at the outlet to the solar storage tank; or at the
outlet to the auxiliary heater.
22. Pump Throttling Valve: May be partially closed
to reduce the flow rate and prevent pump cavitation.
11) ESTIMATED COMPONENT LIFE
You can expect a long useful life from the primary
components in your Cascade Drainback solar water
heating system by adhering to the routine service
and maintenance tips provided above.
The SunEarth solar collector and drainback reser-
voir have a design life of twenty-five to thirty years.
The solar storage tank should last twelve to twenty
years in most water quality areas provided the anode
rod is periodically replaced. The circulating pump
and differential control should last 10 to 15 years
before needing to be replaced. Like EPA mileage
estimates for automobiles, these component design
lives represent average figures for drainback system
components installed in the United States. The life
of your components may vary.
To obtain warranty service, please see the com-
pleted Appendix on the back of this manual with
your installation contractor contact information or
contact SunEarth Inc. for the name of an authorized
service agent near you.
12) SYSTEM OPERATING PARAMETERS
12.1 Collector Loop Pressure
The pressure in the solar collector loop should be
within 0 – 20 PSIG.
12.2 Circulation Flow Rate
The flow rate in the collector loop should be 0.5 –
4 GPM when the pump first comes on (filling the
collector loop). Once the collector loop is full and
water starts to siphon down the return piping the
flow rate will normally increase and should be 0.8 –
5 GPM with the system circulating.
12.3 Temperature Differential
The temperature difference between the collector
outlet sensor (T1) and the solar tank sensor (T2)
should be 4 ºF – 30ºF when the system is circulating.
12.4 Fluid Level
The water level when the system is not circulat-
ing (pump stopped) should such that the drainback
tank not less than 75% full. When the system is
circulating (pump running); the water level in the
drainback tank should be not less than 25% full.
The drainback tank should never be pumped dry in
normal operation as this may result in damage to the
circulator pump.
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