
9
PLUMBING
The storage tank should be placed in a location to best minimize heat loss. It should be placed as
close to the system return line as possible. Adequate ventilation and access for possible future
service work are important considerations. In order to prevent possible water damage in case of
tank leakage, a pan with a ¾” drain line should be installed.
As illustrated in the System Schematic on page 12 of this manual there are very specific
requirements as to valve, thermostat, and pump placement.
The following component equipment should solder in place according to their specific relative
locations as outlined in the System Schematic.
1. Circulation Pump (Part #4) - Taco 006BC4 Circulation Pump
2. Thermometers (Part #11) - Letro SL-2D In-Line Thermometer w/ temperature range
of 50to 220 F.
3. Boiler Drains (Part # 12) - BD-050 (½”), or BD-075 (¾”) Boiler Drains on both
Supply and Return lines.
4. Ball Valves (Part #14) - BV-050 (½”), or BV-075 (¾”) Ball Valves on both
Supply and Return lines.
5. Cold Water Inlet Valve - GV-075 (¾”) Gate Valve.
6. Mixing Valve - Watts 70A-075 (¾”) Mixing Valve.
AUTOMATIC DIFFERENTIAL CONTROL
Power to the circulation pumps is controlled by an automatic differential control that has two
temperature sensors. One sensor is located on the outlet of the solar collector and the other
sensor is located on the storage tank behind the lower access panel. When the storage tank
sensor detects water temperatures cooler than the desired temperature set on the control, and if
the collector sensor is 8F warmer than the storage tank sensor, the automatic control turns on
the circulation pump to harvest the energy available from the sun. When the desired temperature
is met, or when the solar collector sensor drops to within 4 degrees of the storage tank sensor, the
control turns off the circulation pump. (This on/off differential can be set to 24º/4º rather than
the 8º/4º.)
The automatic control has a three-position switch - ON, AUTO or OFF. (Sometimes this switch
is located on the inside of the cover.) During normal operation, the control is switched to AUTO
where the control will turn the circulation pump on and off at the appropriate times. When
switched to ON, the control sends power to the circulation pump. When switched to OFF, the
control turns the circulation pump off.
THE AUTOMATIC CONTROL HAS A HIGH LIMIT STORAGE SETTING THAT CAN BE ADJUSTED
FROM 110°F TO 200ºFAND IS TYPICALLY PRESET TO 140°F.