Operation; Figure 134 Temperature And Humidity Sensor Terminal, Viewed From The Rear Of The Unit-600Mm; Figure 135 Temperature And Humidity Sensor And Filter Clog Sensor Viewed From Front Of Unit-300Mm - Emerson Liebert CRV User Manual

14.0 O
PERATION

Figure 134 Temperature and humidity sensor terminal, viewed from the rear of the unit-600mm (24")

models
Air Temperature Suction
Probe Position-Only
With Temperature Control

Figure 135 Temperature and humidity sensor and filter clog sensor viewed from front of unit-300mm (12")

DX models
Temperature
and humidity
sensor
The control system compares the relayed information with the programmed setpoint and proportional
band values and performs one of the following operations:
Cooling—Direct expansion mode (DX): The compressor is started and the cold refrigerant flows
through the evaporator, thus cooling the air passing through it. Liebert recommends using the supply
temperature sensor to control the cooling capacity of the Liebert CRV, but cooling can be managed
from any of the temperature sensors. The supply temperature is an accurate representation of the
actual heat rejection the Liebert CRV needs to perform. Chilled water Liebert CRV models will
modulate the cooling capacity from 0% to 100% and DX models will modulate the cooling capacity
from 20% to100% compressor capacity. To avoid short-cycling the compressor during room heat load
changes, the Liebert CRV will not deactivate the compressor until the air temperature is below 150%
of temperature setpoint when in Remote or Supply Air Control or below 200% of temperature setpoint
when operating in Return Air Control.
Chilled Water Mode (CW)—The three-way valve is opened and the chilled water flows through the
coil, thus cooling the air passing through it.
Temperature
and Humidity
Sensor Terminal
153

Operation

Filter Clog
Sensor
® ™
Liebert CRV