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Fifth Revision
BULTER SUN SOLUTIONS
9/07/2007
SERVICE MANUAL
Figure 2.9
Heat Exchange Surface Areas vs. Loop Temperature & Collector
Efficiency
The effects of heat exchanger surface area on closed loop temperatures for different types
of solar collector are shown in Figure 2.9. The small, 2 square foot surface area of the
“Solar Wand” drives the loop temperature of the system up compared to a RheemRuddTM 20 square foot surface area heat exchanger, with the 7 square foot surface area
Quad RodTM in the middle. Increasing the loop temperature increases the solar collector
heat losses. The “Solar Wand” works well with collectors whose heat losses do not
increase dramatically with temperature. The solar collector has a much greater effect on
system performance than the surface area of the heat exchanger for selective absorber
surface solar collectors. For black painted solar collectors the higher loop temperatures
dramatically decrease system performance. The “Solar Wand” should only be used with
selective absorber surface solar collectors.
All SRCC OG-100 certified collectors meet the above criteria and also must have passed
a cold-water shock test, where cold water is sprayed on a collector stagnated by solar
heating without fluid flow. SRCC certified collectors must also pass a 30-day stagnation
test without fluid loop degradation or other collector damage.
2.5
Circulation Pump
The circulation pump provided is of the seal-less, centrifugal type. The magnetic rotor is
driven by chasing an electronically created rotating magnetic field, which is transmitted
through a thin stainless steel wall. The electronics are on the outside of the wall and the
pump rotor/impeller is on the inside with the heat transfer fluid so the electronic pumps
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SERVICE MANUAL: Solar Butler 1.0 Solar-Assisted Hot Water System