AboveAir Technologies MissionCritical MC-2x2, Engineering Manual

Page: 16 / 24

Above Air
™
MissionCritical
™
A/C’s
AboveAir Technologies
(MC22-L12)
16 Guide Specifications
Guide Specifications - MC
-
2x2
™
Mission Critical (1-3 Tons)
2.5 Accessories

2.5.1 Plenum Discharge Box
(UF - Up-Flow Units)
A (2-way, 3-way or ducted) plenum
discharge box shall be provided for field
installation to the top of the up-flow unit.
The plenum box shall be 18.5 inches
high, insulated and powder-coat painted
to match the color of the unit.

2.5.2 Floor Stand
A ____ inch high floor stand shall be
factory provided for field installation. The
floor stand shall have adjustable legs
with vibration isolation.

2.5.2.1 Turning Vanes
Turning vanes shall be factory provided
with the floor stand to direct the dis -
charge air either to the front or rear of
the unit.

2.5.3 Condensate Pump
(Factory Installed - UpFlow)
A condensate pump shall be factory
provided and installed within the indoor
evaporator section (Up-Flow Air Pattern
Configurations) . The condensate pump
shall be provided with dual internal float
switches: one for pump operation initia -
tion and the other for pump reservoir
overflow safety.
( Note: Down-Flow unit Condensate Pump
Option requires field installation of the pump
outside of the A/C unit. A condensate pump
fused power supply terminal connection
shall be factory provided within the A/C unit
evaporator.)

2.5.4 Hot Gas Bypass Systems

2.5.4.1 Hot Gas Bypass To
Evaporator Inlet
Each refrigerant circuit shall be pro -
vided with a factory installed hot gas
(discharge) bypass valve. The hot gas
bypass valve shall be designed to supply
hot gas to evaporator inlet as required to
provide coil freeze-protection and capac -
ity modulation under low load conditions.

2.5.4.2 Hot Gas Bypass To
Suction Line with
Quench Valve
(VCH/XPU-CCU/CWU-CGU
Remote Condensing Units
3
rd
Line Not Required!)
Each refrigerant circuit of the Split DX
system shall be provided with a fac -
tory installed hot gas bypass system to
include: hot gas (discharge) bypass and
desuperheating quench. The hot gas
bypass system shall be designed to sup -
ply hot gas and liquid refrigerant to the
suction line as required to provide coil
freeze-protection and capacity modula -
tion under low load conditions. All hot
gas bypass components shall be factory
installed and shall not require additional
field refrigerant lines on split DX sys -
tems.

2.5.5 Suction-Line Accumulator
Each refrigerant circuit shall be provided
with a factory installed Suction-Line Ac -
cumulator to prevent liquid slugging of
the compressor and excessive refriger -
ant dilution of the compressor oil during
low load conditions. The accumulator
shall return refrigerant and oil to the
compressor at a sufficient rate to main -
tain both system operating efficiency and
proper oil level. The accumulators shall
be wrapped with a 1/2” closed-cell neo -
prene insulation to prevent sweating.

2.5.6 Main Power, Non-Fused
Disconnects
(Remote Condenser Section)
The remote condensing unit (or con -
denser) shall be factory provided with
a main power non-fused disconnect for
field installation. The disconnect shall be
NEMA rated for indoor or outdoor instal -
lation as required.

2.5.7 Firestat
(Factory Installed)
A Firestat shall be factory installed in the
return air stream of the unit and wired to
the A/C unit electrical control panel. The
Firestat shall shut-down all A/C system
operations upon sensing a high return air
temperature condition.

2.5.8 Smoke Detector
(Factory Installed)
A Smoke Detector shall be factory
installed in the return air stream of the
unit and wired to the A/C unit electrical
control panel. The Smoke Detector shall
shut-down all A/C system operations
upon activation.

2.5.9 Remote Water-Leak
Detector
A remote water-leak detector shall be
factory provided for field installation. The
remote water-leak detector shall be wired
to shut down all A/C unit water producing
functions upon sensing a water leak.

2.5.10 Flow Switch -
Water/Glycol Condenser
A factory installed flow switch shall
shut-down / lockout compressor opera -
tion prior to the high refrigerant pressure
switch alarm upon sensing a loss or low
dx condenser water/glycol flow. A flow
switch alarm shall be indicated both via
MC-2000 microprocessor display and
auxililary dry-contact terminal connec -
tion.

2.5.11 Compressor Acoustic /
Sound Jacket
Each compressor shall be provided with
a factory installed compressor sound
jacket with snap closure system for ease
of removal and reinstallation. Sound
jackets shall have a noise reduction coef -
ficient (NRC) of 85 per ASTM and C-423
and a sound transmission lost (STC) of
11 per ASTM E-90.