06-06
5.2 CHILLED WATER SYSTEMS
The A/E shall investigate the following:
A. CENTRAL CHILLED WATER PLANT: For the domiciliaries and nursing homes
located on the grounds of the medical center, availability of the
chilled water from the existing central chilled water plant (if any)
shall be investigated. If it is not feasible to tie into the existing
central chilled water plant due to lack of spare capacity, or need to
make extensive changes to the existing piping and pumping system, or
due to elaborate and cumbersome chilled water piping distribution
involved, a dedicated chilled water system (described below) shall be
evaluated.
B. DEDICATED CHILLED WATER SYSTEM: The dedicated chilled water system
shall comprise of air cooled (or water cooled) chillers compete with
pumping and piping. The following criteria shall apply for sizing and
selecting the chilled water system:
1. Cooling Load (60 tons and below): Provide a single chiller with
multiple compressors.
2. Cooling Load (Above 60 tons): Provide two chillers, each with
multiple compressors.
C. PIPING/PUMPING ARRANGEMENT: The arrangement shall be compatible with
the source of chilled water. The use of the primary/secondary,
primary/secondary/tertiary, chilled water system (with variable speed
secondary/tertiary pumps and two way, modulating, chilled water
control valves) is essential when the chilled water is available from
a central chilled water plant or a dedicated chilled water system
with multiple chillers. See Supplement, Attachment No. 2, 3, and 4
for suggested piping layouts.
D. SYSTEM CONTROLS:
1. General: The chillers shall be equipped with the factory furnished
safety controls and flow switches which shall be interfaced with
the operating controls to meet the intent of the system design.
The operating controls shall be selected by the designer to suit
the system capacity and configuration. The following guidelines
are offered:
a. Single Chiller Installation: With a single chiller, the
capacity control shall be generally based on monitoring the
return chilled water temperature and/or maintaining variable
fixed leaving chilled water temperature.
b. Two Chillers Installation: With two chillers, primary/secondary
pumping arrangement shall be used with variable speed drives
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