2.12.10 FREEZE PROTECTION Chilled Water System
Adequate protection shall be provided for chilled water to avoid potential
problems associated with freeze up.
2.12.10.1 CHILLED WATER: The following measures shall be evaluated to protect
the coils and pipes carrying chilled water. Select one or more options, as
deemed necessary.
(a) Heat Tracing: All exposed chilled water piping shall be heat traced with
thermostatically controlled electric tape. See VA Master Specification
Section 15705, HVAC PIPING SYSTEMS and Article 2.16 for emergency power
requirements.
(b) Remote Air Cooled Condenser: Entire chilled water piping shall be kept
indoor by locating only the air-cooled condenser outdoors.
(c) Partial Draining: Only the exposed chilled water piping shall be drained.
The indoor chilled water piping shall remain filled with water. This measure
will require drain valves and isolating valves at appropriate locations in
the chilled water piping.
(d) Automatic Flow Activation: The chilled water flow shall be activated
automatically when the chiller is idle, below preset ambient temperature
and/or chilled water temperature in exposed piping to prevent freeze up.
(e) Use of the glycol water solution shall be limited due to the following
reasons:
(1) Loss of heat transfer efficiency, approximately 5-10 percent, in the
chiller and cooling coil operation.
(2) Higher pumping cost due to higher pump head.
(3) Higher initial cost, associated with glycol, fill station, piping, pump,
etc.
(4) Higher maintenance costs associated with additional equipment and higher
2.12.11 FREEZE PROTECTION-Condenser Water System
The cooling towers shall be winterized as follows:
(a) Provide thermostatically controlled basin heaters if the cooling tower is
scheduled to remain in operation during fall and winter. All exposed
condenser water piping shall be heat traced.
(b) Partial Draining: Only exposed condenser water shall be drained during
fall and winter when the cooling tower is not in operation. With this
measure, it will be possible to partially save the water chemicals. A set of
drain and isolation valves will be required to facilitate draining.
2.12.12 PRE-INSULATED CHILLED WATER PIPING
2.12.12.1 UNDERGROUND CHILLED WATER PIPING: The basic requirements shall be
in accordance with the VA Master Specification, Section 15706, HVAC PIPING
SYSTEMS. The principle features are:
HVAC DESIGN MANUAL
2-46
HVAC SYSTEMS AND EQUIPMENT
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