HWA1-A & HWA1-H
Air/Water chillers and heat pumps with axial fans
8
The addition of an expansion module allows to manage by mean of the controller beyond to an external modulating or two
positions 3-way valve, both the free cooling regulation and the circulators of the desuperheater and of the total heat recovery,
and the eventual double pumps with alternating optimized use of them according to the number of unit’s working hours.
5.9
CONTROL AND PROTECTION DEVICES
The units are standard equipped with the following control and protection devices: 3-phase monitor allows to stop the unit if the
phase sequence is incorrect or if the voltage of at least one phase is different with 15% from the others, return water temperature
sensor with antifreeze function which is installed on the return water pipe line from the plant circuit, operation sensor installed on
the water return pipe from plant circuit, low pressure transducer, high pressure transducer, compressors discharge temperature,
relief valve on low pressure side which opens at temperatures higher than 68°C, compressor inlet temperature sensor, suctions
compressors suction temperature sensors, air outside temperature sensor (HWA1-H), thermal protection switch for fan motors,
thermal protection on each compressor, water side flow switch to protect the evaporator, high pressure HP flow switch with
manual reset installed on the outlet pipe of the compressors near the high pressure intake of service. The below components are
supplied also as standard:
The integral protection module which is installed inside the compressors’ electrical box which detects by means of an
included sensor the real winding temperature and stops the compressor’s operation when the limit temperature is
reached and is a required protection also for the operation with low evaporation pressures especially when the thermal
protection on the power supply circuit is not sure.
High pressure transducer for condensation control, defrost cycle termination and shutdown of compressors in sequence
according to the maximum permitted pressure (allows to produce hot water at 50°C even with outside temperatures
above 40°C in bi-compressor heat pump units).
5.10
HYDRAULIC CIRCUIT
The
HWA1-A/HWA1-H
series can be supplied with an incorporated hydronic kit which includes: in addition to the flow switch, and
the other components already mentioned, pressure gauges at the inlet and pressure intake at the outlet of the heat exchanger to
assess the load losses, one or two circulating pump with AC motor which are suitable for the utilization of chilled water and
directly managed by the controller on-board unit in both on-off and modulation operations depending on the adopted solution.
It is also possible to install an internal inertial tank with external closed-cell foam insulation material and with capacity of about
180 liters.
The 3 way flow switching valve is also supplied in the free cooling versions joined together with the 3 row aluminum fins
-
copper
piping heat exchanges.
5.11
FAN SPEED CONTROL
One-speed fan motors with high pressure transducer as standard, available also for chillers of two-speed fan motors of star/delta
(Y-Δ) connection. This type of regulation controlled by the microprocessor is necessary for optimizing the condensation pressure in
cooling operation mode in order to allow the correct operation of the unit with a wide outdoor temperatures range. The
modulating control inverter with EC brushless motor
can be supplied as optional particularly for heat pump units or when the
chilling operation mode is required at outdoor air temperatures below -5°C, this feature
is supplied as standard on both cooling
only and heat pump models HWA1-A 0285 and HWA1-H 0285
.
