Safety And Control Devices - Casals QUANTICA EEC Manual De Instalación, Operación Y Mantenimiento

12. SAFETY AND CONTROL DEVICES

• Supply air temperature probe
Passive sensor type NTC 10kΩ. Positioned on the supply air side, downstream of the heating/cooling units, it is used to monitor
the temperature of the air supplied to the room. It is installed in combination with the temperature control accessories (water
coils or post-heating electric resistance). Through this probe it is also possible to control eventual air delivery temperatures in
the environment that are too cold in summer or too hot in winter.
• Return air temperature probe
Passive sensor type NTC 10kΩ. Positioned on the room air intake and upstream of the filtering section, its purpose is to mon-
itor the temperature of the air extracted from the room to be treated. Always present in all units, it is used as a control probe
of the room temperature set and for the management of the summer free-cooling function.
• Outdoor air temperature probe (fresh air)
Passive sensor type NTC 10kΩ. Positioned on the fresh air intake and upstream of the filtering section, it is used for monitoring
the temperature of the fresh air entering the heat recovery unit. Always present in all units, it is used in combination with the
room air intake temperature probe to manage the summer free-cooling function.
• Exhaust air temperature probe
Passive sensor type NTC 10kΩ. Positioned on the air outlet and downstream of the plate heat exchanger, it monitors the tem-
perature of the air exhausted from the unit. It is installed in combination with the defrosting kit with the function of controlling
the exhaust temperature of the plate heat exchanger in order to avoid freezing of the same during the winter operation of
the unit.
• Defrost kit
The defrost system consists of an exhaust air temperature probe and an electrical heater positioned inside the unit on the
room return air side, downstream of the filtering section and upstream of the plate heat exchanger. If the temperature down-
stream of the plate heat exchanger should drop dangerously below the set point and thus avoid the danger of freezing, the
electrical heater is activated, which, through a power modulation control (with PWM signal), heats the air extracted from the
room and consequently increases the exhaust temperature.
In this way, the ice formation on the exchanger plates is avoided. The power modulation control allows a considerable energy
saving thanks to the fact that the electrical energy absorbed by the electric heater is just the one strictly necessary to bring
the unit back to optimal working conditions.
• Differential pressure switch
This component is used to monitor the clogging status of the air filters. There are two pressure switches for each unit, one
installed on the fresh air filter section and one located on the room return air filter section. If one of the filters has a pressure
difference greater than the recommended limit, an alarm is displayed on the user interface.
• Differential pressure transducer
Active type transducer with 4-20mA current output signal. It is installed only in the CONTROL EVO CAV and CONTROL EVO
COP versions and positioned in the electrical panel. In the CONTROL EVO CAV versions it is connected with the pressure socket
available on the supply fan, the purpose is to keep the constant flow rate set by the user.
In the CONTROL EVO COP versions, one pressure tap measures the static pressure at the supply outlet, the other one meas-
ures the atmospheric pressure. The aim is keeping the constant supply static pressure. This type of regulation leads to a VAV
(Variable air Volume) system that can be used in those applications where a heat recovery unit serves several rooms.
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