HWMC
30
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RG66008809 - Rev 00
6
CONTROL AND SAFETY DEVICES
All the control and safety devices are set and tested in the factory before
the unit is dispatched.
6.1 CONTROL
DEVICES
6.1.1 Service
thermostat
The service thermostat activates and deactivates the compressor according
to the demand for chilled water (cooling mode) or heated water (heat pump
mode), as determined by a sensor installed on the water exchanger outlet.
This device is governed by the microprocessor control (see also the manual
regarding the microprocessor).
6.2 SAFETY
DEVICES
6.2.1
HIGH PRESSURE SWITCH
The high pressure switch stops the compressor when the outlet pressure
exceeds the set value.
6.2.2
LOW PRESSURE SWITCH
The low pressure switch stops the compressor when the intake pressure
falls below the set value.
6.2.3 ANTI-RECYCLE
TIMER
The function of the timer is to prevent excessively frequent compressor
starts and stops. This device is a function included in the microprocessor
control; it prevents the compressor from starting up again after a stop until
a set period of time has elapsed (approximately 5 minutes).
6.1.2
CONTROL DEVICE SETTINGS
Control devices
Set point min
max differential
Service thermostat
°C
7
5
15
2
(outlet water temp. cooling mode)
Service thermostat
°C
45
25
53
2
(outlet water temp. heat pump mode)
6.2.7
SAFETY DEVICE SETTINGS
Safety device
Activation
Differential
Resetting
Maximum pressure switch (bars)
42
Manual
Minimum pressure switch (bars)
2
Automatic
Antifreeze thermostat (°C)
4
3
Manual
Water differential pressure switch (bars) 0,050
0
Automatic
Water safety valve (bars)
4
6.2.4 ANTIFREEZE
THERMOSTAT
The antifreeze thermostat situated at the evaporator outlet performs a dual
function: it prevents ice from forming in the evaporator in the event of an
excessive decrease in the water flow; it stops the unit in the event of a failure
of the service thermostat.
This device is governed by the microprocessor control (see also the chapter
regarding the microprocessor).
6.2.5
WATER DIFFERENTIAL PRESSURE SWITCH
The water differential pressure switch stops the unit in the event of an
excessive reduction in the water flow, thus protecting it from the formation
of ice (chiller operation) and excessively high condensation temperatures
(heat pump operation).
6.2.6
WATER SAFETY VALVE
The water safety valve opens when the pressure within the water circuit
reaches a level that may cause damage to the unit.
