3.1.1.2
Array Piping
Collector array piping shall be installed in a reverse-return configuration
so that path lengths of collector supply and return are of approximately
equal length. All piping must be coded with fluid type and flow direction
labels in accordance with Section 09900 PAINTS AND COATINGS.
3.1.1.3
Array Support
Array support shall be installed in accordance with the recommendations of
the collector manufacturer. Structural members requiring welding shall be
welded in accordance with AWS D1.2 for aluminum and welders should be
qualified according to AWS B2.1.
3.1.2
Storage Subsystem
Solar storage tank penetrations shall be installed as shown so that cold
water inlet to storage tank and outlet from storage tank to collector array
are located near the bottom of the tank, and inlet from collector array and
outlet to load are located near the top of the tank.
3.1.3
Transport Subsystem
3.1.3.1
Flow Rates
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NOTE: The reverse-return strategy is important to
proper array operation. Because this strategy
results in what may be initially perceived by the
contractor as excess piping, it is important that
the array piping be shown and indicated on the
drawing as satisfying this requirement. Rules,
methodology, and examples of the reverse-return
strategy are given in TM 5-804-2. Collector loop
flow rate should be determined by multiplying the
recommended flow rate per collector by the number of
collectors to be installed. Collector headers must
be located such that there is no possibility of air
pockets. Items to be shown on the drawings must
include:
a. Flow rate through collector loop based on
recommended flow per collector
b. Reverse-return piping shown and noted
c. Valves, strainers, automatic controls, and all
accessories
d. Pipe pitch for draining.
Although solar energy system performance is not
strongly dependent on the effectiveness of the
particular heat exchanger used, it is very important
to ensure that it is sized properly. Use of the
approach and return temperatures stated in this
paragraph ensures that the effectiveness of the heat
exchanger is within acceptable limits. The hot side
return temperature can be less than 49 degrees C
(120 degrees F) if the designer feels that the
effectiveness should be greater than 0.5. When
multiplate heat exchangers are used, the
SECTION 13600A
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