Data creazione 10/09/03 DS03I009GB--00 Pagina 49 di 59
During the freecooling phase, the corresponding valve deviates the flow of water to the freecooling coil,
located upstream of the evaporators. At the same time, the freecooling fans are activated according to the
average evaporator outlet temperature. In this way, as the outside temperature is less than the return water
temperature, the latter is cooled.
In the case of INTERNAL freecooling, the freecooling fans are the same as the condenser fans.
Consequently, during this phase only, these fans are operated at 100% if a compressor is active, or
alternatively modulate (according to the average evaporator outlet temperature) if no resources are active.
In the case of EXTERNAL freecooling, the freecooling fans are managed by the central module and
therefore are completely independent from the condenser.
The control valve, when the freecooling conditions are present, is switched 100% to the FC coil. It only
deviates the flow to the evaporator if the average evaporator outlet temperature falls below a threshold
value, as described further on.
Freecooling modulation
The capacity of the FC coil is modulated by:
a) varying the speed of the fans
b) varying the percentage of water flow deviated to the FC coil
The modulation of the capacity provided due to freecooling is performed based on the average evaporator
outlet temperature, while considering the following limits.
1. When at least one compressor is on, and in any case when the average water outlet temperature is
above the step deactivation threshold, freecooling is at the maximum. (Fans at 100% and valve 100% to
the FC coil).
2. When the fans are on, the valve switches 100% to the FC coil.
Explanatory graph
Current Set Point
IsLastStep
Delta MinFC
Delta MaxFC
Ventilation
IsValveFC
Valve YV1 Mod. (AO6)
Average evaporator outlet
temperature
0%
100%
MinFan
Modulating Valve and Fans
To Next Page
Loading...
Need help?
General
