12
4 - WATER CONNECTIONS
4.11 FREE-COOLING - OPTION
When the temperature of the fresh air is lower than the temperature of
the return water of the system, the free-cooling version lets you recover
cold from the external environment, reducing the work of the compres-
sors all the way down to nothing.
USE OF ANTI-FREEZE SOLUTIONS
The heat carrier used in the systems that include a Free-Cooling devi-
ce require a glycol solution (usually an ethylene type). This substance
is required because the Free-Cooling units are intended to be installed
where the temperature can drop to very low levels during certain times
of the year. The percentage of glycol in the solution depends on the
low temperatures that can be expected in the place of installation.
Therefore, this parameter is at the discretion of the system designer.
Summer
cooling of the solution is ensured by the refrigerating cycle with
operation of the compressors (C) as in a traditional chiller ;
the Free-Cooling (Bh) coils are not involved.
Ev
Vm
V3
Fa
Bc
Bh
Ve
SL
F
VL
Wi
Wo
Ae 35 °C
15 °C
10 °C
STAGIONE ESTIVA
C
100%
Intermediate season
The energy savings variable between 0 and 100%, based on the tem-
perature difference between fresh air and the system request.
If the unit detects that the fresh air temperature (Ae) is suitable:
1. it inverts the position of the 3-way valve (V3), forcing the
solution to travel through the Free-Cooling coils (Bh) before
reaching the evaporator (Ev);
2. it sets the fans (Fa) at maximum speed to obtain maximum
cooling of the solution from the fresh air;
3. the solution thus undergoes an initial cooling which is free and
natural;
Key
Ae fresh air
Bc condensino coil
Bh water coil
C scroll compressor
Ev plate evaporator
F dryer filter
Fa fan
SL liquid light
Ev
Vm
V3
Fa
Bc
Bh
Ve
SL
F
VL
Wi
Wo
Ae 11 °C
15 °C
10 °C
13 °C
STAGIONE INTERMEDIA
C
50%
Winter
The three way valve (V3) is in the same position as in the previous
case;
the temperature of the fresh brings the solution at the outlet of
the Free-Cooling coils (Bh) to the temperature required for
use;
the microprocessor control completely deactivates all com-
pressors (C), providing all cooling power at no cost, as oppo-
sed to standard units;
if the difference between the temperature of the fresh air (Ae)
and that required for use is such that the temperature of the
solution at the outlet of the Free-Cooling coils (Bh) drops
below the set point required for use (which does not compro-
mise unit safety, because of the glycol in the solution), the
microprocessor modulates fan speed (Fa), turning them off if
necessary. When the fans are off, if the temperature (Wo)
continues to drop, the 3-way valve (V3) positions itself as in
summer operation, changing to digital and allowing the set
point to be maintained.
V3 3-way valve
Ve electronic expansion
valve
VL cock on the liquid line
Vm cock on the supply line
Wi water inlet
Wo water outlet
4. the remaining cooling is provided by the refrigeration cycle,
with compressors in stepped operation (power absorbed
proportional to the degree of stepping);
If the temperature of fresh air increases, the microprocessor will auto-
matically revert operation to summer mode, ensuring the same condi-
tions requested by the user.
Ev
Vm
V3
Fa
Bc
Bh
Ve
SL
F
VL
Wi
Wo
Ae 0 °C
15 °C
10 °C
10 °C
STAGIONE INVERNALE
C
0%
SUMMER
INTERMEDIATE SEASON
WINTER
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