General Specification
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CAT 258 • REBEL APPLIED ROOFTOP
2 .19 Energy Recovery
A.
The rooftop unit shall be provided with an AHRI
certified rotary wheel air-to-air heat exchanger in
a cassette frame complete with seals, drive motor
and drive belt. The energy recovery wheel shall
be an integral part of the rooftop unit with unitary
construction, power supply and controls and does
not require field assembly. Bolt-on energy recovery
units that require field assembly and section to
section gasketing and sealing are not acceptable
B.
The energy recovery wheels supplied must meet the
scheduled capacity, and air pressure drop.
C.
The wheel capacity, air pressure drop and
effectiveness shall be AHRI certified per AHRI
Standard 1060. Thermal performance shall be
certified by the manufacturer in accordance with
ASHRAE Standard 84, Method of Testing Air-to-Air
Heat Exchangers and AHRI Standard 1060, Rating
Air-to-Air Heat Exchangers For Energy Recovery
Ventilation Equipment.
D.
The rooftop unit shall be designed with a track so
the entire energy recovery wheel cassette can slide
out from the rooftop unit to facilitate cleaning.
E.
The unit shall have 4" Merv 8 filters for the outdoor
air before the wheel to help keep the wheel clean
and reduce maintenance. A dirty filter switch and
alarm shall be provided on the Energy wheel filter
rack
F.
The total energy recovery wheel shall have an
aluminum substrate and a 3 angstrom desicant and
shall have an adjustible purge for field balancing.
G.
A VFD shall be provided an modualed for wheel
capacity and frost prevention control by the unit
contorller.
H. A electric preheat coil with SCR control shall be
provided and modulated to prevent frost on the
energy recovery device. Provide sizing equivalent to
the schedule.
I.
The rooftop unit with the energy recovery wheel
shall incorporate the economizer operation. Units
with economizers and energy recovery wheels shall
have a bypass damper. When the unit is in the
economizer mode of operation the energy recovery
wheel shall stop and the bypass dampers shall be
opened. The outdoor air shall be drawn through the
bypass dampers to reduce the pressure drop of the
outdoor airstream.
2 .20 Discharge and Return Plenum Options
A.
A supply air discharge plenum shall be provided.
The plenum section connection shall have a bottom,
right, left, or top discharge opening consult the
schedule and drawings for the final orientation.
2 .21 Condensing Section
A.
All Units shall provide the Energy Efficiency
specified EER and IEER per the schedule
equipment or higher.
B.
Condenser fans shall be direct drive, axial type
designed for low tip speed and vertical air discharge.
Fan blades shall be constructed of steel and riveted
to a steel center hub. Condenser fan motors shall
be heavy-duty, inherently protected, three-phase,
non-reversing type with permanently lubricated ball
bearing and integral rain shield.
C.
Condenser coils shall be an all aluminum design,
and mounted on polymer brackets, to minimize
di-electric corrosion. The aluminum tube shall be a
micro channel design with high efficiency aluminum
fins. Fins shall be brazed to the tubing for a direct
bond. Each condenser coil shall be factory leak
tested with high-pressure air under water.
D.
Condenser coils shall be protected from incidental
contact to coil fins by a coil guard. Coil guard shall
be constructed of cross wire welded steel with PVC
coating
E.
Head Pressure Control
1.
Units shall have at least one condenser fan per
circuit to maintain positive head pressure and an
ambient temperature based fan cycling control to
provide mechancial cooling down to 50°F
2.
Units shall have at least one condenser fan per
circuit to maintain positive head pressure and
a pressure transducer feedback per circuit to
provide mechancial cooling down to 50°F
3.
Units shall have at least one condenser fan per
circuit to maintain positive head pressure and a
VFD on each cirucit to modulate condenser fans
to provide mechancial cooling down to 25°F
4.
Units shall have at least one condenser fan per
circuit to maintain positive head pressure and a
VFD on each cirucit to modulate condenser fans
to provide mechancial cooling down to -10°F
5.
Units shall have at least one condenser fan
controlled to maintain positive head pressure.
SpeedTrol condenser fan speed control shall be
added to the last fan OFF on each refrigeration
circuit to provide cooling operation to ambient
temperatures down to 0°F. Fan speed control
shall be field adjustable.
F.
Each unit shall have multiple, heavy-duty scroll
compressors. Each compressor shall be complete
with gauge ports, crankcase heater, sight-glass,
anti-slug protection, motor overload protection and a
time delay to prevent short cycling and simultaneous
starting of compressors following a power failure.
Compressors shall be isolated with resilient rubber
isolators to decrease noise transmission
Summary of Contents for DPSA
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