Assortment / System Description

Central applications
Automation station for HVAC supply and demand signals and manual control for lighting and blinds
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Under favorable condition (chilled water temperature = FreeCTChw), the
central plant can output the signal that free cooling is available (FreeCAvl) via
grouping to the rooms. The rooms take the offer and go to comfort condition to
use free energy for cooling with comfort setpoints. Free cooling demand is
returned via the enumerated chilled water demand signal.
The central function can disable the chilled water equipment in the rooms
based on outside temperature. The cooling sequences in the group are locked
as soon as the configured value for the outside temperature is reached. Back
and forth switching can be prevented using a time constant and hysteresis.
Description Name Default value
Cooling limit CLm 14 [°C]
Time constant for cooling limit TiConCLm 2 [h]
Hysteresis for cooling limit HysCLm 1 [K]
Condensation in rooms can be prevented by shifting the chilled water
temperature setpoint. Grouping records all active condensation monitors. The
resulting adjustment is based on the percentage of active condensation alarms.
SpTChwShftMax Maximum shift of setpoint chilled water temperature 10 K
SttActvCdnMon Setpoint shift starts at this percentage of active
condensation monitors
10 [%]
EndActvCdnMon The setpoint shift is set to the maximum value at this
percentage of active condensation monitors.
50 [%]
Figure: Condensation prevention characteristic curve
The valve actuator is operated from time to time to prevent it from blocking
after longer periods of inactivity (cooling in the winter). The valve actuator is
controlled to lose as little heating energy as possible.
The central function for chilled water supply chain runs the valve kick function;
the configuration can be adapted as needed.
Description Name Default value
Kick value KickVal 50 [%]
Kick time TiKick 2 [Min]
Kick cycle KickCyc 500 [h]
Free cooling
Chilled water
Deactivate sequences
Preventing
condensation
Valve protection