10 Control Operation
The Vertiv™ Liebert® MCV Premium Efficiency Control takes about 30 seconds to boot during which time, the LED on the
Premium Efficiency Control Board reads “888.” When fully booted, “F00” displays, then the value for F00. When using the
control, the condenser fan(s) respond less than 5 seconds after receiving a compressor or signal from the indoor unit.
Consider using UPS equipment on both data center cooling units and Liebert® MCV condensers to maintain uninterrupted
cooling capability.
For the first 60 seconds of operation after the compressor turns on, the condenser fan(s) run at a factory set fixed speed,
based on ambient temperature: faster at higher temperatures, slower at lower temperatures. After 60 seconds, the control
adjusts the fan speed based on the liquid pressure transducer. If the liquid-pressure transducer fails, the condenser uses
temperature sensors to control the fan speed based on the liquid line temperature. The condenser fans continue to operate
for approximately 30 seconds after compressors turn Off.
The Liebert® MCV fans have various alarm conditions, such as loss of voltage and loss of control signal, that stop the
condenser fans. When an alarm condition is no longer present, the fans turn on automatically if compressors are On.
10.1 Vertiv™ Liebert® EconoPhase Pumped RefrigerantEconomizer
withaVertiv™ Liebert® DSE System
Liebert® DSE systems are designed to provide precision air conditioning to computer racks in a data center or computer room
as efficiently and effectively as possible.
A Liebert® DSE system with Liebert® EconoPhase is composed of individually-shipped components or components
assembled together on skids. Some examples are:
System example 1
• Liebert® DSE—High efficiency, floor mounted indoor unit
• Liebert® MC Condenser—Air cooled microchannel condenser, premium version
• Liebert® EconoPhase—Liebert® EconoPhase pumped-refrigerant economizer (PRE)
System example 2
• Liebert® DSE—High efficiency, floor mounted indoor unit
• Liebert® MCV Heat rejection skid—Air cooled microchannel condenser, premium version with a Liebert®
EconoPhase pumped refrigerant economizer (PRE)
The Liebert® EconoPhase PRE is an add on module for use with an air cooled Liebert® DSE system. The Liebert® EconoPhase
allows the system to switch to Liebert® EconoPhase operation when the outdoor temperature is low enough to provide the
required temperature difference between the inside air and the outside air, which, in turn, provides significant energy savings
because the compressor(s) do not operate. At lower temperatures, the system switches one or both circuits from Compressor
Mode to Pump Mode. The pump consumes roughly one-tenth of the power consumed by the compressor.
The Liebert® EconoPhase system maintains this energy efficiency by employing the heat absorption properties of a liquid
(pumped refrigerant) through a phase change. Refrigerant is pumped as a liquid, becomes a gas within the Liebert® DSE
evaporator and is then returned to the condenser where it condenses to a liquid. The subcooled liquid refrigerant from the
condenser is run directly into the Liebert® EconoPhase pumps and circulates back to the Liebert® DSE unit (see Figure 10.1
on the next page). The system operates as a typical air cooled direct expansion system when outdoor ambient conditions are
unfavorable to Liebert® EconoPhase operation. The pumps in the Liebert® EconoPhase PRE are turned off and bypassed
during compressor operation.
10 Control Operation Proprietary and Confidential ©2024 Vertiv Group Corp. 33
Vertiv™ Liebert® MCV Installer/User Guide
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