Assortment / System Description

VAV application
Night cooling
18
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HysTDiffDw
pChw
Hysteresis minimum difference
dew point temperature/chilled
water temperature
TDiffDwpC
hwMin
Minimum difference dew point
temperature/chilled water
temperature
TChwPm Chilled water temperature TDwp Dew point temperature
(calculated)
Figure: Dew point temperature monitoring parameters
Dew point temperature monitoring must be enabled.
Description Name Default value
Enable dew point temperature
0:No
1:Yes
EnTDwp 0:No
18.30 Night cooling
The plant operating mode cools a room using cooling outside air. The central
function sends a "Night cooling request" to the group member rooms. The
decision as to whether night cooling makes sense and is energy efficient is
made at the central function. Various coordination signals between the primary
plant and room automation do the following via central functions:
● Switch on the fans,
● Set the mixed air dampers to 100% outside air,
● Lock all other equipment including heating coils, cooling coils, humidifier.
Night cooling only occurs under the following conditions:
● The room is vacant (Economy or Protection).
● The outside temperature is above an adjustable setpoint of 9 °C.
● The temperature difference to cooling is sufficiently large, i.e. room
temperature - outside temperature > 7 K.
● The temperature deviation from room temperature and temperature
setpoint is sufficiently large, i.e. room temperature > room setpoint + 2 K.
Description Name Default value
Night cooling
0: Inactive
1: Active
NgtCReq 0: Inactive