Optional Factory-Installed Features—Self-Contained and Evaporator Units
Liebert
®
Mini-Mate2
™
12
3.5 Free-Cooling
Free-cooling option includes separate cooling coil, three-way, slow-close valve and separate supply
and return piping. Free-cooling is activated when the water temperature reaches a field-adjustable
temperature, typically 45°F (7°C). The valve is rated for 300psi (2068kPa) working pressure.
Air-cooled units can be specified with free-cooling coils, allowing chilled water to be the primary
cooling and the air-cooled section to be the backup. Water/glycol units have two sets of piping, each
with three-way water regulating valves, increasing options of free-cooling sources, such as external
chilled water or glycol from a drycooler loop (see Figure 7). The free-cooling coil is designed for
closed-loop applications using properly treated and circulated fluid. Not available with SCR reheat
options.
Figure 7 Free cooling option—example
3.6 Optional Configuration—Prop Fan Condensing Units
Outdoor Prop Fan Condensing Units are also available in the following optional configurations:
• Condenser coils can be phenolic-coated for extended coil life in coastal areas.
3.7 Optional Configurations—Water/Glycol-Cooled Units
Water/glycol-cooled units are also available with the following piping options:
• Two-way water regulating valve with 350 psi (2413kPa) design pressure.
• Three-way water regulating valve with 150psi (1034kPa) design pressure.
• Three-way water regulating valve with 350psi (2413kPa) design pressure.
3.8 Optional Configuration—Chilled Water Units
Chilled water units are available with the following valve option:
• Three-way, slow-close, motorized chilled water valve rated for 300psi (2068kPa) working
pressure. Valve is non-spring return.
NOTE
If free-cooling is applied to an open water tower, a heat exchanger must separate the tower
water from the free-cooling loop.
Free -
Cooling
Coil
Water/Glycol
Condenser
Field Piping
Liebert Mini-Mate2
Water Temperature
Sensor
Drycooler
A free-cooling coil allows the system to take advantage of a
primary chilled water source or colder water/glycol temperatures
available during colder outdoor temperatures. When the fluid
temperature goes below 45°F (7.2°C), cooling switches to
free-cooling operation, bypassing compressor operation.
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