FORM 145.05-EG2 (618)
74
JOHNSON CONTROLS
Fan Motor
Fan motor shall be heavy-duty 1750 rpm open drip-proof (ODP) type with grease lubri-
cated ball bearings. The motors shall meet applicable EPACT efficiency requirements.
Optionally, TEFC motor shall meet applicable EPACT efficiency requirements. Motors
shall be mounted on a heavy-duty adjustable base that provides for proper alignment
and belt tension adjustment. The minimum service factor shall be 1.15 fixed pitch V-
belt drives with a minimum of two belts shall be provided. Drive shall be selected at a
service factor of 1.15. Optionally, the Drive shall be selected at a service factor of 1.5.
Completed fan assembly, including fan, drive, motor assembly, and framework, shall be
statically and dynamically balanced at the factory. Entire fan assembly shall be mount-
ed on 2-inch nominal deflection spring isolators. Optionally, 2-inch nominal deflection
spring isolators with seismic restraints shall be available. The inlet to the fan assembly
shall be isolated from the unit with a flexible connection. The entire fan assembly shall be
isolated within the unit, thus eliminating external spring isolation. Use of standard waffle
pads between the bottom of the unit and the concrete housekeeping pad is sufficient. Fan
section ceiling and walls directly facing the fan outlet air will have double wall construc-
tion with 20-gage perforated galvanized steel.
Variable Frequency Drives (VFD)
Airflow modulation and static pressure control shall be achieved by increasing or de-
creasing the speed of the variable frequency drive (VFD). The VFD shall be approved for
plenum duty applications. In event of VFD failure, the bypass contactor shall be energized
using operator interface. In the bypass mode, the fan shall operate at full design airflow
and the VFD can be removed for service. The compressors shall be staged to meet the
discharge air temperature set point.
The supply air fan drive output shall be controlled by the factory-installed unit control
system. The VFD status and operating speed shall be monitored and displayed at the unit
control panel. A factory mounted, field adjustable duct high-limit safety control shall be
available to protect ductwork from excessive duct pressure. The installer shall provide
and install sensor tubing from [a single unit mounted sensor] [two unit mounted sensors]
to the duct location(s).
Optional VFD and bypass contactor shall be completely wired and run tested at the fac-
tory. Motor overload relay is sized to protect the motor during bypass mode.
COMPRESSORS
Each unit shall have multiple high-efficiency; heavy-duty, suction-cooled scroll compres-
sors. The compressors shall be single speed operating at 3450 rpm at 60 Hz. A refrigerant
pressure transducer shall be installed on the discharge and suction side of each compressor.
These sensors shall be used to indicate high pressure, low pressure, motor protection, and
identify other conditions that could frost the DX coil. A high pressure switch sensing refrig-
erant pressure at the compressor discharge will disable compressor by opening contactor
circuit in case of high refrigerant pressure. Each compressor shall include motor overload
protection, and a minimum three-minute interstage timer to prevent short cycling. The com-
pressors shall be isolated internal to the unit by rubber in shear isolators. Each refrigerant
circuit shall be charged with POE oil and Refrigerant HFC-410A. The compressors shall be
independently protected for overload using circuit breakers/manual starters. Each compres-
sor will have individual refrigerant circuit. Compressor RLA will not exceed 21.2 Amps at
460 Volts or 47 Amps at 208 Volts. Compressors shall be 15 nominal horsepower or lower.
Guide Specifications (Cont’d)
Summary of Contents for L-Series
Page 1: ...FORM 145 05 EG2 618 ENGINEERING GUIDE Water Cooled Self Contained Units L Series Vertical ...
Page 4: ...FORM 145 05 EG2 618 4 JOHNSON CONTROLS THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 14: ...FORM 145 05 EG2 618 14 JOHNSON CONTROLS THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 35: ...FORM 145 05 EG2 618 JOHNSON CONTROLS 35 OVERVIEW OF SERVICE CLEARANCES LSWU025 040 MODELS ...