Emerson Liebert DS Series, User Manual

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Piping
91
9.3.2 Air-Cooled Condenser with Liebert Lee-Temp “Flooded Condenser” Head Pressure
Control System
The Liebert Lee-Temp system consists of a modulating type head pressure control valve and insulated
receivers with heater pads to ensure operation at ambient temperatures as low as -30°F (-34.4°C).
The Liebert Lee-Temp system can be used with any Liebert DS compressor choice.
Liebert Lee-Temp Piping
Two discharge lines and two liquid lines must be field-installed between the indoor unit and the
outdoor condenser. See Figures 67 and 69 for details.
Liebert Lee-Temp Controlled Materials Supplied
• Built-in, pre-wired condenser control box
• Air-Cooled condenser
• Piping access cover to be reinstalled when piping is complete (models with one to four fans only)
• Bolts—four per leg (3/8" x 5/8")
• Terminal block for two-wire, 24V interlock connection between unit and condenser
• Condenser legs—four with 1-fan, six on two-, three- and six-fan models and eight on four- and
eight-fan models
• Bolts—six per receiver (3/8" x 1")
• Lee-Temp system:
• Insulated storage receiver—one per circuit
• Head pressure control valve with integral check valve - one per circuit
• Service valve—one per circuit
• Pressure relief valve—one per circuit
• Liquid level sight glass—two per circuit
• Check valve—one per circuit
Lee-Temp Leak Check and Evacuation Procedure
Proper leak check and evacuation can be accomplished only with all system solenoid valves open and
check valves accounted for.
1. If unit power is available, open the unit liquid line solenoid valves using the evacuation function
for System #1 and System #2 in the diagnostic section of the Liebert iCOM control. If unit power
is not available, a field-supplied 24VAC / 75VA power source must be directly connected to each of
the unit solenoid valves.
2. Attach a jumper hose from the service valve fitting on the outlet of the receiver and the Schrader
fitting on the discharge header of the condenser. Front-seat the service valve approximately
two (2) turns.
3. For semi-hermetic compressors, connect refrigeration gauges to the suction and discharge service
valves of both compressors.
4. For scroll and digital scroll compressors, connect refrigerant gauges to the suction rotalock valves
and discharge line Schrader valves (see Note above) on both compressors.
5. Starting with Circuit #1, open the service valves and place a 150 PSIG (1034 kPa) of dry nitrogen
with a tracer of refrigerant. Check system for leaks with a suitable leak detector.
6. With pressure still in Circuit #1, open the compressor service valves in Circuit #2. If pressure
increases in Circuit #2, the system is cross-circuited and must be rechecked for proper piping. If
there is no pressure increase, repeat the leak check procedure for Circuit #2.
NOTE
Lee-Temp heater pads require a separate, continuous electrical source. See nameplate on unit
for proper voltage.
NOTE
Systems with scroll or digital scroll compressors include a factory-installed check valve and an
additional downstream Schrader valve with core in the compressor discharge line. Proper
evacuation of the condenser side of the compressor can be accomplished only using the
downstream Schrader valve. See piping schematic ( Figure 69 ).