06-06
4.5 HEAT PUMPS
The use of the closed loop, water cooled, incremental, heat pump
system shall be evaluated for mild climate locations and for the
buildings with relatively large interior area. The heat shall be the
primary source of heating with steam to hot water, or electric
resistance heat, as back up.
5. COOLING SYSTEMS
5.1 GENERAL
The mechanical cooling for the spaces shall be provided by chilled
water systems, or direct expansion systems, or modular heat pumps
(with closed loop air to water heat source). Based on the life cycle
cost analysis, the most cost effective system shall be selected.
5.2 CHILLED WATER SYSTEMS
The A/E shall investigate the following:
A. CENTRAL CHILLED WATER PLANT: For the office buildings 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 422 kW (120 tons and below): Provide a single chiller
with multiple compressors.
2. Cooling Load Above 422 kW (120 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.
D. SYSTEM CONTROLS:
1. General: The chillers shall be equipped with the factory furnished
safety controls and flow switches which shall be interfaced with
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