adjustable superheat thermostatic expansion valve with external equalizer
matched to coil, capillary or thermostatic control, and a pilot solenoid
controlled, leak-tight, four-way refrigerant flow reversing valve.
2.5.6
Unit Controls
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NOTE: In regards to head pressure control, insert
the appropriate minimum or lowest expected ambient
temperature. Delete head pressure controls if
inapplicable. Delete low cost cooling if
inapplicable. In those areas where the outdoor
seasonal climatic conditions permit, an outdoor
temperature sensing unit (dry bulb) may be used in
an external control circuit to take advantage of
outside air to satisfy the cooling load. Under such
conditions, the control circuit would lock out the
compressors and position the outdoor and return air
dampers to allow 100 percent fresh air to be
circulated. Enthalpy controls will not be used.
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Unit shall be internally prewired with a [24] [120] [_____] volt control
circuit powered by an internal transformer. Terminal blocks shall be
provided for power wiring and external control wiring. Unit shall have
cutoffs for [high] [high and low] pressure, [and] low oil pressure for
compressors with positive displacement oil pumps, [supply fan failure] [and
safety interlocks on all service panels]. Head pressure controls shall
sustain unit operation with ambient temperature of [_____].
Adjustable-cycle timers shall prevent short-cycling. Multiple compressors
shall be staged by means of a time delay. Unit shall be internally
protected by fuses or a circuit breaker in accordance with UL 1995. Low
cost cooling shall be made possible by means of a control circuit which
will modulate dampers to provide 100 percent outside air while locking out
compressors.
2.6
UNITARY EQUIPMENT, SPLIT SYSTEM
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NOTE: A remote condensing unit includes both the
condensing coil and the compressor. A remote
condenser includes only the condensing coil.
Air-cooled, water-cooled, and evaporatively-cooled
air-conditioning units with capacities less than
39.5 kW (135,000 Btuh) will be rated in accordance
with ARI 210/240.
Air-cooled, water-cooled, and evaporatively-cooled
air-conditioning and heat pump units with capacities
greater than or equal to 39.5 kW (135,000 Btuh) will
be rated in accordance with ARI 340/360.
Air-cooled heat pump units with capacities less than
39.5 kW (135,000 Btuh) will be rated in accordance
with ARI 210/240.
Water-cooled heat pumps used in closed water loop
systems (water-source systems) will be rated in
SECTION 15700A
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