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Site Preparation and Installation
Liebert
®
Mini-Mate2
™
36
Figure 23 System piping with indoor water/glycol cooled condensing unit
5.8 Optional Equipment Piping
5.8.1 Free-Cooling Coil
The free-cooling coil is a secondary coil located downstream of the DX coil. The free-coiling coil does
not operate at the same time as the DX coil. A temperature sensor is factory-mounted to the free-
cooling piping. If the water temperature is less than the set temperature (usually 45°F [7.2°C]), the 3-
way valve opens to allow chilled water flow to the free-cooling coil and the compressor is locked off. If
the water temperature is above the set temperature, the 3-way valve closes (bypasses) and enables
the compressor. To keep deposits from building up in the free-cooling coil, an adjustable timer is
factory-set to flush every 400 minutes.
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 24).
NOTE
If the free-cooling coil is piped to an open water tower, a CU/NI (copper-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.
*
*
Evaporator
Coil
Tube-in-Tube
Condenser
Tube-in-Tube
Condenser
High-Pressure
Switch
Scroll
Compressor
Hot Gas
Bypass
Solenoid
Valve
H
o
t
G
a
s
B
y
p
a
s
s
C
o
n
t
ro
l
V
a
l
v
e
Liquid Injection
Valve
Suction Line Male Quick
Connect Coupling
Liquid Injection
Valve Bulb
Liquid Line
Male Quick
Connect
Coupling
Water/Glycol
Return Line
Fluid Return
From Unit
Fluid Supply
To Unit
Water/Glycol
Supply Line
Shutoff **
Valves
Hose
Bibs **
2 - Way Water
Regulating Valve
Fluid
Return
From Unit
Fluid Supply
To Unit
3 - Way Water
Regulating Valve
(Optional)
Suction Line Female Quick
Connect Coupling
Liquid Line
Female Quick
Connect
Coupling
Service Access
Ports
Filter
Drier
Expansion
Valve
External
Equalizer
Sensing Bulb
FIELD PIPING
FACTORY PIPING
DPN000214
Rev. 1
* Use Liebert sweat adapter kit with field
hard piping. Close-coupling option available with MCD.
** Components are not supplied by Liebert but are
recommended for proper circuit operation and maintenance.