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Site Preparation and Installation
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2.8 Optional Equipment Piping
2.8.1 Free-Cooling Coil (GLYCOOL)
The free-cooling coil is a secondary coil located upstream of the DX coil. To take maximum advantage
of available free-cooling, the secondary coil may operate at the same time as the DX coil. A tempera-
ture sensor is factory-mounted to the free-cooling piping. When fluid temperature is sufficiently below
the room temperature, cooling is provided by circulating the fluid through the secondary cooling coil
(flow is controlled by a motorized valve). Compressors are staged on if needed to supplement the free-
cooling. To keep deposits from building up in the free-cooling coil, the coil is flushed periodically.
On water-cooled systems, the free-cooling coil outlet can be field piped to the condensing unit inlet,
provided a 3-way regulating valve has been installed within the water/glycol condensing unit (see
Figure 21).
Figure 21 Optional free cooling coil (3-way valve) on water/glycol units
NOTE
If the free-cooling coil is piped to an open water tower, a CU/NI (cupro-nickel) type coil must
be ordered to prevent corrosion of the copper tubes; or a heat exchanger must separate the
tower water from the free-cooling loop.
SL-11088Pg12