3.1.4
Control Subsystem
3.1.4.1
Differential Temperature Controller
Automatic control equipment shall be installed at the location shown in
accordance with the manufacturer's instructions. Control wiring and sensor
wiring shall be installed in conduit. [Collector temperature sensor shall
be mounted in a temperature sensor well in the fluid stream along the top
manifold of a bank between two adjacent collector units.] [Collector
temperature sensor shall be provided by differential temperature controller
manufacturer and mounted directly on the absorber plate by the
manufacturer.] Unless otherwise indicated, operators, controllers,
sensors, indicators, and like devices when installed on equipment casings
and pipe lines shall be provided with stand-off mounting brackets, bases,
nipples, adapters, or extended tubes to provide clearance, not less than
the thickness of the insulation, between the surface and the device. These
stand-off mounting items shall be integral with the devices or standard
accessories of the controls manufacturer unless otherwise approved.
Clamp-on devices or instruments where direct contact with pipe surface is
required shall be exempted from the use of the above mounting items. All
control wiring shall be color coded and identified with permanent numeric
or alphabetic codes.
3.1.4.2
Sequence of Operation
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NOTE: The following on/off set differentials are
common for liquid systems:
Pump on = 7 to 11 degrees C (12 to 20 degrees F).
Pump off = 2 to 4 degrees C (3 to 8 degrees F).
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The differential temperature controller sensing temperature difference
between the fluid in a solar collector and water in the storage tank shall
start solar collector loop [and storage loop] pumps[s] when the temperature
differential (Delta T - ON) rises above [8] [_____] degrees C [15] [_____]
degrees F, and shall stop the pump when the differential (Delta T - OFF)
falls below [3] [_____] degrees C [5] [_____] degrees F.
3.2
INSPECTION AND TESTING
3.2.1
Inspection
Contractor shall make system available for inspection at all times.
3.2.2
Testing Prior to Concealment
3.2.2.1
Contractor shall demonstrate to Contracting Officer that all piping has
been hydrostatically tested, at a pressure of 862 kPa 125 psi for a period
of time sufficient for inspection of every joint in the system and in no
case less than 2 hours, prior to installation of insulation. Expansion
tank and relief valves shall be isolated from test pressure. No loss of
pressure shall be allowed. Leaks found during tests shall be repaired by
replacing pipe or fittings and the system retested. Caulking of joints
shall not be permitted.
SECTION 13600A
Page 28
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