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Optional Factory-Installed Features - Evaporator/Chilled Water Units
Liebert
®
Mini-Mate2
™
10
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 condensing units can be matched with evaporators using free-cooling coils with chilled
water sources to serve as backup cooling. When matched with a water/glycol condensing unit, a
three-way water regulating valve is recommended for the condensing unit to simplify piping to the
main supply pipes. The coil is designed for closed-loop applications using properly treated and
circulated fluid. Not available with SCR reheat options.
Figure 7 Free-cooling arrangement
3.6 Optional Configurations—Prop Fan Condensing Units
Outdoor Prop Fan Condensing Units are also available in the following optional configurations:
• High ambient, top discharge models for catalog capacities at ambient temperatures up to 105°F
(40°C).
• Quiet-Line models for low noise level conditions (below 56 dBA) and catalog capacities for
ambient temperatures up to 95°F (35°C).
• Condenser coil(s) can be phenolic-coated for extended coil life in coastal areas.
3.7 Optional Configurations—Water/Glycol Condensing Units
Indoor Water/Glycol Condensing Units are also available with the following piping options:
• Two-way water reg. valve with 350 psi (2413kPa) design pressure.
• Three-way water reg. valve with 150psi (1034kPa) design pressure.
• Three-way water reg. valve with 350psi (2413kPa) design pressure.
NOTE
If free-cooling is applied to an open water tower, an optional copper-nickel (CuNi) coil is
required to prevent premature corrosion, or a heat exchanger must separate the tower water
from the free-cooling loop. The copper-nickel coil requires an extended lead time.
Free-
Cooling
Coil
Water/Glycol
Condenser
Field Piping
Water Temperature
Sensor
Liebert Mini-Mate2
Drycooler
Free-cooling option: A second
cooling coil allows the system to take
advantage of colder outdoor
temperatures and bypass compressor
operation.
When the water temperature goes
below 45°F (7°C), cooling switches
over to free-cooling operation. A
separate chilled water source can
also be used with air-cooled systems.