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 3.1 Free-cooling arrangement
NOTE: If free-cooling is applied to an open water tower, an optional cupro-nickel (CuNi) coil is required
to prevent premature corrosion, or a heat exchanger must separate the tower water from the free-
cooling loop. The cupro-nickel coil requires an extended lead time.
3.6 Optional Configurations—Prop Fan Condensing Units
Outdoor Prop Fan Condensing Units are also available in the following optional configurations:
• High ambient models for providing catalog capacities at ambient temperatures up to 105°F
(40°C).
• Quiet-Line models for low noise level conditions (below 58 dBA) and for providing catalog
capacities at ambient temperatures up to 95°F (35°C).
• Condenser coils can be phenolic-coated for extended coil life in coastal areas.
Vertiv | Liebert Mini-Mate2—2 and 3 ton Technical Data Manual | 10
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