31
7.18 - Variable speed fans (option 17)
Air-cooled.units.fitted.with.the.variable.speed.fans.option.
allow for reducing the total unit consumption by adjusting
the fan speed to the current operating conditions.
The control determines the optimum fan speed based on the
current compressor capacity, outdoor air temperature, and
leaving water temperature.
7.19 - Evaporator heater option (30XA)
The evaporator heater protects the evaporator against frost
when the unit is stopped at low ambient air temperature. The
heater is activated in the case of low outdoor air temperature
conditions.
7.20 - Free cooling option (30XA)
In air-cooled units only, this option allows for the direct use
of low outdoor air temperature to cool the water circuit
without activating the compressors.
The direct-expansion free cooling system uses the principle of
the natural migration of the refrigerant from the evaporator to
the condenser. The fans and a refrigerant pump ensure the transfer
of the liquid refrigerant from the condenser to the evaporator,
which accounts for low power consumption.
The free cooling option enables automatic operation as well
as combined operation of mechanical cooling (compressor
operation) and free cooling (FREECOOL – Free cooling).
The control determines which circuit is allowed to run free
cooling. Each refrigerant circuit can operate independently.
Cooling operation may be performed in the following
combinations:
•
two circuits in mechanical cooling
•
two circuits in free cooling
•
one circuit in mechanical cooling and one circuit in
free cooling
The free cooling option is available for dual-circuit units. It
requires the installation of SIOB board that controls the
operation of the motorised mechanical changeover valves
and the operation of the refrigerant pump.
Free cooling option is enabled based on the following criteria:
•
The temperature difference between the outdoor air
temperature and the controlled water temperature.
The.threshold.can.be.configured.by.the.user.(GEN_
CONF.–.General.Configuration)
•
The maximum operating time in free cooling (Full
Load Timeout) when the water temperature setpoint
is not reached (
Full Load Timeout,
GEN_CONF –
General.Configuration)
7.21 - Dry cooler option (30XW)
30XW units may come with the dry cooler option that enables
the control of a Carrier dry cooler.
The chiller and the dry cooler have to be connected through
a LEN RS-485.
7.22 - Hydronic kit option (30XA)
The hydronic kit option allows for continuous monitoring of
the.water.flow.rate.
Hydronic kit option provides the following parameters:
•
Inlet and outlet water pressure (PUMPSTAT in the
Main menu)
•.
Evaporator.flow.rate
•
Evaporator capacity
The. water. flow. rate. is. based. on. the. pressure. difference.
between the evaporator inlet and outlet pressures and the
evaporator pressure drop curves.
The.evaporator.capacity.is.calculated.according.to.the.flow.
rate, the water constant, and the difference between the
entering and leaving evaporator water temperature.
7.23 - 30XA-ZE and 30XW-ZE units (HFO)
The Touch Pilot system may also control air-cooled and water-
cooled units with R-1234ze refrigerant (HFO).
Please note that this option comes with advanced electrical box
fan protection. In the case of the electrical box fan failure, the
unit is shut down and alarm 10100 is triggered.
7.24 - High condensing temperature option (30XW)
7.24.1 -
R134a configuration
For water-cooled units only, the economizer enables the
increase of the maximum condensing threshold. This means
that the saturated condensing temperature can reach a
maximum of 63°C (145°F) compared with a maximum of 50°C
(122°F).for.units.that.are.not.fitted.with.this.option.
7.24.2 -
HFO configuration
For HFO units (30XW units with R-1234ze refrigerant), the
high condensing option authorizes the saturated condensing
temperature to reach a maximum of 70°C (158°F) compared
with.a.maximum.of.55°C.(131°F).for.units.that.are.not.fitted.
with this option.
7.25 - Maximum condenser leaving water
temperature option (30XW)
For water-cooled units only, this option allows the user to
limit the condenser leaving water temperature to 45°C
(113°F) and enables to limit the current absorbed by the
compressor. When the condensing temperature reaches 44°C
(111°F), the increase in the compressor loading is stopped.
When the temperature exceeds 45°C (113°F), the compressor
is unloaded.
