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3.4 --- Starting and stopping
For the units provided with the POWERFACE control, you
can switch on/off using the main switch.
For the units provided with HIROMATIC interface:
Start up the unit by pressing the Hiromatic ON---OFF
S
push button (confirmed by SYS.ON on the display).
Stop the unit by pressing the Hiromatic ON---OFF push
S
button (confirmed by SYS.OFF on the display).
4 --- Operation
The unit operation is completely automatic. The sequence
below explains (with the assistance of Fig. 8 ---Operation
diagram) how the unit operates (see also Fig. 9 and Fig. 10
--- Refrigerating circuit):
1) The temperature sensor, positioned inside the HPSE
evaporating unit, informs the control about the condition
of the return air.
2) The control compares the information received with the
programmed Set Point value (= minimum indoor tem-
perature) and Proportional Band (and Differential in the
versions with optional Freecooling), activating the condi-
tioner's air treatment modes as follows:
Cooling (Fig. 8a)
After switching the unit on, the evaporator fan starts immedi-
ately whereas the compressor is started only when the tem-
perature of the room to be conditioned exceeds the set value.
In the HPSCxxA/L unit versions, the condensing unit fan
starts automatically if the condensing pressure increases
(control through Variex), while in the other versions the fan/s
is/are controlled by a pressure switch ensuring a limit lower
than the condensing pressure. The air taken in by the evapor-
ator fan enters the unit through the side intakes, passing
through the filters, and then reaches the evaporator. The cold
refrigerant flows inside the evaporator pipes, thus cooling the
air passing through it. The treated air is conveyed into the
conditioned room through the supply outlet. The heat taken
from the room and that generated by the conditioner motor
operation is rejected through condensing coil located in the
external condensing unit and cooled with outside air by the
condenser fan. For the operation logic of the controls see
chapter 5.
Heating (optional)
Heating of the air is achieved by means of electric heaters,
located in the air flow and activated according to the logic set
on the controls (see chapter 5).
Freecooling (optional)
When the temperature of the outside air is sufficiently below
that of the inside air it is possible to use this difference to pro-
vide cooling inside the room by direct intake of the outside air,
i.e. without using the compressor. In this way it is possible to
achieve considerable energy savings. When the required
conditions occur, the servo---motor, managed by the Power-
Face control, opens the modulating damper which separates
the flow of the inside air and outside air. Outside air, drawn
into the room by the fan, is exhausted through an overpres-
sure damper* which is installed on an outside wall of the
room and is protected by an external rainproof grille*. The
degree of opening of the damper is determined as a function
of the temperature set point and the return air temperature.
4.1 --- Control of the condenser fan speed
("HPSCxxA/L " models only)
A sensor is positioned so as to detect the condensing pres-
sure of the refrigeration gas. On the basis of this information,
an electronic device (Variex) modulates the fan speed in
order to keep the condensing pressure within the permitted
range. In this way, besides optimizing the compressor oper-
ation, you can have a reduction of the sound pressure level
(mainly during the night), easier start---up of the compressor
at low temperatures and some energy saving.
For the calibration of the speed controller refer to chap. 6.
4.2 --- Emergency cooling (optional)
4.2.1 --- Emergency cooling 48VDC
With the 48VDC emergency cooling option, the evaporator
fan, freecooling damper actuator and controls are always
supplied at 48VDC, while the compressor, the condenser fan
and the heaters are connected to the AC mains. If the AC
mains supply fails, the conditioner does not stop but con-
tinues to circulate the air, activating the Freecooling as soon
as the relevant conditions are reached, automatically optim-
ized in the event of mains failure.
IMPORTANT:
For proper operation, the unit must always be fed by 48VDC.
4.2.2 --- Emergency cooling 230VAC---50Hz
In case of AC mains failure, the evaporator fan, freecooling
damper actuator and controls are supplied by a second
230V/1Ph/50Hz supply, arranged by the user (UPS/gener-
ator), ensuring operation in the same way as the 48VDC ver-
sion.
CAUTION:
For safety reasons open the main switch.
5 --- Operating logic
The different unit versions feature different automatic operat-
ing logic, as described below.
5.1 --- Cooling only unit
5.1.1 --- Control logic
The control algorithm is based on single---step regulation for
the mechanical cooling, i.e. compressor start/stop. The con-
trol manages all the activation delays, ensuring correct oper-
ation and extending the operating life as much as possible.
Fig. a) Operation of the cooling only unit
5.2 --- Unit with electric heating
5.2.1 --- Control logic
For the heating and cooling version the control algorithm is
based on single---step regulation for the electric heating and
single step regulation for the compressor (mechanical cool-
ing). The control manages all of the compressor activation
delays as previously described, ensuring its correct oper-
ation and maximising run times.
5.2.2 --- Dead band
In this version the "Dead band" parameter, in the "optional
devices" menu of the PowerFace microprocessor control is
very important, enabling the heating semi---band to be
shirted by inserting a non---sensitive area (ventilation only)
between the set point temperature and the start of the heat-
ing semi---band (see Fig. b). In this way, without having to
alter the proportional band, the electric heating can be acti-
vated at lower temperatures (according to the value set for
the dead band) compared to the standard setting, conse-
quently reducing the energy consumption of the heaters and
optimizing their operation according to the site requirements.
pag. 4
P Band
Cooling only
unit
Set
Cooling
°C
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