06-06
to be cross connected to a central chilled water plant with campus
type secondary chilled water distribution system.
Note that the
tertiary chilled water pumps are actually the secondary chilled
water pumps of the animal research areas.
4. Chilled Water Filter: A cartridge type of water filters shall be
provided across pumps per VA standard Detail 15705.15. The filter
capacity shall not be more than 1% to 2% of the total flow in
circulation.
D. COOLING TOWER TREATMENT: Water treatment for the cooling towers shall
be provided and the equipment location shall be shown on the
drawings. The equipment location shall make an allowance for the
chemical drums (in use and spares) and their movement in and out of
the chilled water plant. If the chemicals feed pump is interlocked
with the cooling tower flow, the treatment chemicals may be put into
the condenser return piping. If a cooling tower bypass is included in
the system design, the bypass should discharge into the cooling tower
basin(s) rather than into the cooling tower outlet piping.
5.3 FREEZE PROTECTION
A. CHILLED WATER: The following measures shall be evaluated to protect
the coils and pipes carrying chilled water. The designer shall select
one or more options as deemed necessary.
1. Heat Tracing: All exposed chilled water piping shall be heat raced
by providing thermostatically controlled electric tape.
See VA
Master Specifications, Section 15705, HVAC PIPING SYSTEMS for the
watts/linear foot loading.
2. Remote Air Cooled Condenser: Entire chilled water piping shall be
kept indoors by locating only the air cooled condenser outdoors.
3. Partial Draining: Only the exposed chilled water piping shall be
drained in the winter season. The indoor chilled water piping
shall remain filled with water. This measure will require drain
valves and isolating valves at appropriate locations in the indoor
chilled water piping.
4. Automatic Flow Activation: The chilled water flow shall be
activated automatically below preset ambient temperature and/or
chilled water temperature in exposed piping to prevent freeze up.
Note:
The use of the glycol solution in the chilled water shall
be avoided due to the following:
a. Loss of heat transfer efficiency (Approximately 5% - 10%
penalty in chiller and coil selections).
b. Higher pumping cost (Due to higher pumping head requirement).
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