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System Components
VALVES IN THE SYSTEM
COLD WATER INLET VALVE – This valve is a conventional gate valve located on the cold inlet to the solar storage tank that allows
you to shut off all the water in the tank. This is an EMERGENCY SHUTOFF VALVE — in the event that there happens to be a leak in
the tank or the associated hot water plumbing in your house. Closing this valve totally isolates the Simple Drainback Tank and the
existing conventional tank from its cold water supply. Whenever this valve is closed, the gas supply should also be turned off to
the conventional tank.
MIXING VALVE – Located at the outlet of the existing conventional backup heater, this valve mixes hot water with cold water to
ensure that hot water in the home does not exceed a certain temperature regardless of how hot the water is in the Simple
Drainback tank. The setting on this valve is variable but a recommended temperature setting is 120F. A good thermostatic Mixing
Valve is a required component of OG-300 certified systems and should be plumbed with brass union connections for ease of
future repair.
TEMPERATURE/PRESSURE RELIEF VALVES – This valve is located on the side of the conventional backup tank in a two-tank
configuration, and is approximately 2” long. Its purpose is to protect your system in the event that it overheats, or for some reason
pressure builds up in the tank beyond 150 lbs. per square inch. Anytime the water temperature reaches 210º this valve will open
and discharge the hot water in your system until the water in contact with this valve reaches approximately 150º, at which time it
will close.
A different P/T Relief Valve is located in the top of the Simple Drainback tank. This is a non-pressurized tank. It’s purpose is to
protect the system in the event the pressure should build to 29 lbs. per square inch or if the temperature reaches 210°F. This valve
will open and discharge the hot water in your Simple Drainback Tank until the pressure and temperature drops. With this valve
installed, the solar loop pressure cannot increase to the potable water pressure in the heat exchanger. Therefore, the solar fluid
cannot backflow into the higher-pressure domestic potable water system.
ISOLATION OR BALL VALVES - There are three (3) of these valves. These three valves are part of the solar bypass used to isolate
the Simple Drainback tank from the existing conventional tank for the two tank configuration. The proper positioning of these
valves is illustrated in diagrams #1 and #2 on page 5
These valves have a 3” lever, which can be rotated back and forth 90º. When the valve handle is parallel to the piping, it is in the on
or flow-through position. When the valve handle is perpendicular to the piping, it is in the off position.
DRAIN/FILL VALVE – There is a Drain/Fill Valve near the bottom of the Simple Drainback Tank. This valve is similar to the spigot
you have on the outside of your house for your garden hose. These valves are used to fill and drain the solar loop with the proper
amount of standard tap water when commissioning. Use a flat screwdriver to open and close.
PUMP ISOLATION VALVES – There are two ball valves located above and below the pump. They can be used to isolate the pump
if it needs to be serviced. The valve above the pump is also used to calibrate the flowrate for the system. See System Start-Up
(pg.14) for details .
THERMOMETERS
In-Line Thermometers are installed on the feed line above the Solar Pump and on the return line above the Simple Drain back
tank. These are used to determine proper system operation. On a sunny day, the difference between these two thermometers is
typically 5°F to 12°F. An optional Thermometer can be located between the solar storage tank and the existing conventional water
heater in two tank configurations.
SOLAR PUMP
Located just above the “to collectors” outlet on the Simple Drainback Tank, the Solar Pump pumps water up through the collector
and back down. This pump may be pre-wired with a 42” line cord so it may be plugged into the 115v receptacle cord on the
SHEM32, or SHEM32E Differential Controller, or it may be hard wired to a Differential Controller without a receptacle.