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c. Higher initial cost (Due to: Glycol, fill station, larger
circulating pumps).
d. Higher maintenance costs (Due to: Possible glycol leak and
disintegration over a period of time).
B. COOLING TOWER: The cooling tower shall be winterized by:
1. Heaters: By providing thermostatically controlled heaters in the
cooling tower basins. This measure shall be used only if the
cooling tower is scheduled to remain in operation during fall and
winter. All exposed condenser water piping shall be heat traced.
2. Partial Draining: The exposed volume of the condenser water shall
be drained during fall and winter and the indoor condenser water
shall be left in the distribution system.
With this measure, it
will be possible to partially save the water chemicals. A set of
drain and isolating valves should be provided, as required, to
facilitate drainage.
5.4 SYSTEM CONTROLS
A. General: The chillers shall be equipped with the factory furnished
safety controls and flow switches which shall be interfaced with the
operating controls. The operating controls shall be selected by the
designer to suit the system capacity and configuration. The following
guidelines are offered:
1. 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.
2. Two Chillers Installation: With two chillers, primary/secondary
pumping arrangement shall be used with variable speed drives for
the secondary pumps, if the pumps are 7.5 HP and larger. For
smaller secondary pumps, the capacity reduction of the chillers
shall be affected without the use of the variable speed drives for
the secondary pumps.
B. Miscellaneous Controls: The chilled water leaving water temperature
can be changed in response to the outdoor temperature on a reset
schedule and this control can be used with or without the flow
control for the chiller operation.
5.5 EMERGENCY ELECTRICAL POWER
A. The following components of the cooling systems shall be provide with
emergency electrical power:
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