4 - 13
Operation
Liebert CRV - PD - 265086 - 11.01.2018
Unit operation is completely automatic. The below sequence explains how the unit operates:
•
The air, sucked in by the continuously operating fans, enters the unit.
•
The air is immediately filtered.
•
The TEMPERATURE sensor or HUMITEMP (tempe rel. humidity) sensor (depends on unit
configuration), verifies the state of the inlet air, and relays this information to the control system.
•
The air is treated and then blown out of the unit.
•
The control system compares the relayed information to the set point and proportional band values
programmed into its memory: it then commands the air conditioner to treat the air as follows (see
also Control manual).
4.1 Cooling
•
Direct expansion mode (DX)
The compressor is started and the cold refrigerant flows through the evaporator, thus cooling the
air passing over it. For compressor operation see Control manual.
•
Chilled water mode (CW)
The three ways valve is opened and the chilled water flows through the coil, thus cooling the air
passing over it.
For valve operation see Control manual.
4.2 Heating
•
Electrical heating (optional): the heating elements heat the air passing over them. There is one
heating steps activate in case of dehumidification if supply air temperature is too low (for heating
logic see Control manual)
4.3 Dehumidification
•
DX mode
The compressors starts and either the air flow or the evaporator surface is reduced (increasing
modulation capacity of compressor), thereby causing dehumidification (refer also to Control man
-
ual).
•
N.B.: If, during dehumidification, the ambient temperature drops below a specified level, dehumidi
-
fication will be stopped if necessary (see LOW LIMIT intervention in Control manual).
In dehumidification mode, the air after passing over the coil it’s reheated (if needed) by electrical
heater to re-stabilize the initial temperature
4.4 Humidification - optional
•
The humidifier creates steam, which is distributed into the air via the steam distribution pipe
4
Summary of Contents for Liebert CRV 300 CW
Page 2: ......
