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Operating the System
22
Three Modes of System Operation
Both single and double tank systems are
designed to accommodate three separate
modes of operation. Your solar water
heating system can, (1) provide 100% solar
operation during good weather, or (2) serve
as a preheater to your electric or gas water
heater adding solar energy when and as
available, or (3) completely bypass the solar
collector loop and solar storage tank and
run 100% on utility power during inclement
weather.
Single Tank Operating Instructions:
100% Solar Operation:
Turn off the thermostatic gas valve to your
solar storage tank. If a water heater time
switch has been installed, set the switch to
the "off" position. If you have a mechanical
timer remove the trippers from the face of
the switch.
Solar Preheat
Leave the thermostatic gas valve to
your solar storage tank on and set the
tank thermostat to the lowest acceptable
temperature setting. The thermostatic gas
valve will come on only when the tank
temperature falls below the thermostatic
set point. If the solar heated water entering
the tank is warmer than the thermostatic
set point, the thermostatic gas valve will
not come on. If you have a water heater
timer, you may preset the timer to turn the
thermostatic gas valve on and off at specified
times throughout the day if desired.
100% Utility Power
Leave the thermostatic gas valve to your
solar storage tank on and close the isolation
ball valves in the collector loop (Nos. 6
and 8). In this mode of operation you must
turn off the circulation pump. To turn the
pump off open the controller and change
the operational setting from automatic to
off. Failure to turn off the pump can quickly
damage the pump motor, shaft, bearings or
impeller.
Two Tank System Instructions:
100% Solar Operation
Follow the instructions for single tank
systems above. You also must change the
position of the three way ball valves above
both the solar storage tank and the back-up
water heater (Nos. 24 and 25). Valve handle
No. 24 must be in the horizontal position.
Valve handle No. 25 must be in the vertical
position. (See Figure 22a, 100% Solar
Operation)
Solar Preheat
Follow the instructions for the single tank
system for setting the thermostatic gas valve
for automatic operation. The three way valve
above the solar storage tank (No. 24) must
be in the vertical position. Each valve handle
(Nos. 24 and 25) must be placed in the
horizontal position. (See Figure 22b, Solar
Preheat)
100% Utility Power
Follow the instructions for the single tank
system above. All three way ball valves
above the heaters (Nos. 24 and 25) must
have the valve handles placed in the
horizontal position. (See Figures 22c, 100%
Utility Power and 22d, Valve Position
Diagram)
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