11
Installation Instructions
PLUMBING (CONT’D)
Hard copper connections to the city cold water supply line and the home hot water feed lines are recommended. The gas-
kets in standard water heater flex hose connectors can become brittle and compressed over time and begin leaking on the
water heater. If not detected in a timely manner even a small drip or leak may cause serious damage to the tank’s electrical
components or, in extreme cases, may cause the tank to leak from the outside in.
The solar system plumbing requires the ability to isolate the solar system from the city cold water supply line by means of
an isolating ball valve, #13 on system schematics.
The solar pump shall be pre-wired with a 42” line cord so that it can be plugged directly into the 115-volt receptacle at the
bottom of the SHEM32 differential control. Pump Isolation Valves (#5 on schematics) are included above and below the
pump so repairs or routine system maintenance can be completed without introducing air into the system or draining the
Heat Transfer Fluid (water).
A high quality thermostatic mixing valve is a required component in all OG-300 certified systems and should be plumbed
at the outlet of the existing conventional tank with brass union connections for ease of future repair or replacement. The
specified mixing valve shall be the Watts model 70A-075 or equal. It should have an operating range between 95°F and
140°F. The mixing valve should be set to 120°F. The temperatures generated by your Simple Drainback System will vary
throughout the year. In the Northern Hemisphere the water temperature will be hottest in the spring and summer months
while cooler temperatures are to be expected from November through March. On sunny days system temperatures may
range from 110°F to 180°F depending upon the season and hot water demand. The mixing valve described above blends
the hot and cold water supplies to deliver hot water to your fixtures at a safe, controlled temperature. A pressure relief
valve is required on the collector loop portion of the system. (#16 on system schematic) The drainback tank contains a port
specifically for its installation.
WARNING: SCALDING CAN OCCUR WITHIN FIVE SECONDS WHEN WATER TEMPERATURES
APPROACH 140° F. THE MIXING VALVE SHOULD BE ADJUSTED BY THE INSTALLATION
CONTRACTOR TO PROVIDE WATER TO DWELLING FIXTURES AT NO MORE THAN 120°F
The 3/4” cold water supply line to the Simple Drainback Tank must be insulated with minimum 7/8" thick insulation for 3/4"
pipe insulation to a minimum distance of 5’ behind the storage tank, or to the wall if closer than 5’. When utilizing the
existing hot watertank, a solar bypass is required in all OG-300 certified systems, as illustrated in Figure #5 and #6.
Building materials adjacent to solar components should not be exposed to the elevated temperatures of the solar hot
water system. Insulation or separation of the solar system and building materials will prevent exposure to the elevated
temperatures.
SIMPLE
DRAINBACK
TANK
SIMPLE
DRAINBACK
TANK
Figure #6, Two Tank Configuration - Gas
Figure #5, Two Tank Configuration - Electric