Specifications

1.7 MAINTENANCE
A. Maintenance of the chillers shall be the responsibility of the owner.
PART 2 — PRODUCTS
2.1 ACCEPTABLE MANUFACTURERS
A. McQuay International
B. (Approved Equal)
2.2 UNIT DESCRIPTION
Provide and install as shown on the plans a factory assembled, charged, and run-tested water-cooled packaged
chiller. Each unit shall be complete with two (one on Model WMC 145) multi-stage, oil-free, magnetic bearing,
hermetic centrifugal compressors. Each compressor shall have variable frequency drive operating in concert
with inlet guide vanes for optimized unit part load efficiency. The evaporator, condenser, and expansion valve
shall be common to both of the compressors. Two-compressor chiller units shall be capable of running on one
compressor with the other compressor or any of its auxiliaries inoperable or removed.
2.3 DESIGN REQUIREMENTS
A. General: Provide a complete water-cooled, dual hermetic compressor centrifugal water chiller as
specified herein. Machine shall be provided according to standards, Section 1.2. In general, unit shall
consist of two magnetic bearing, completely oil-free, compressors, refrigerant condenser and
evaporator, and control systems including variable frequency drive, operating controls and equipment
protection controls. Note: Chillers shall be charged with a refrigerant such as HFC-134a, not subject
to phase-out by the Montreal Protocol and the U. S. Clean Air Act.
B. Performance: Refer to schedule on the drawings. The chiller shall be capable of stable operation to ten
percent of full load with standard ARI entering condensing water relief, without hot gas bypass.
C. Acoustics: Sound pressure for the unit shall not exceed the following specified levels. Provide the
necessary acoustic treatment to chiller as required. Sound data shall be measured according to ARI
Standard 575-87 and shall be in dB. Data shall be the highest levels recorded at all load points.
Octave Band
63 125 250 500 1000 2000 4000 8000 dba
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2.4 CHILLER COMPONENTS
A. Compressors:
1. The unit shall have one or two, two-stage, magnetic bearing, oil-free, hermetic centrifugal
compressors. The compressor drive train shall be capable of coming to a controlled, safe stop in
the event of a power failure.
2. Movable inlet guide vanes, acting together with variable speed, shall provide unloading. A
microprocessor controller, dedicated to each compressor shall coordinate the vane and speed
control to provide optimum unit efficiency.
B. Refrigerant Evaporator and Condenser:
Catalog WMC-4 51