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E N G L I S H
µC
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- +030220731 - rel. 1.2 - 26.10.2007
- Disable load default values
H22:
If this parameter is set to 1, it disables the possibility of restoring the default parameters using the
PRG button at power ON.
- select supervisor protocol
H23: establishes the protocol used for the connection to the supervisor from the serial board RS485
H23 = 0: CAREL protocol (baud rate 19200,…)
H23 = 1: Modbus protocol
• Alarm settings: parameters (P*)
- Flow switch alarm delay when starting pump
P01: Establishes a delay in the recognition of the flow switch alarm when starting the pump (this allows
the flow-rate to stabilise). In the event of alarms, the compressors are stopped immediately, ignoring the
times.
- Flow switch alarm delay in steady operation
P02: Establishes a delay in the recognition of the flow switch alarm in steady operation, so as to filter any
variations in flow-rate or air bubbles present in the water circuit. In the event of alarms, the compressors
are stopped immediately, ignoring the times.
- Low pressure alarm delay at compressor start
P03: Establishes a delay in the recognition of the low pressure alarm when the compressor starts, so as
to allow stable operating conditions to be reached. This delay is also counted when reversing the 4-way
valve in the refrigerant circuit.
- Part load in high pressure
P04: enable or disable the part load operation of the circuit in high pressure.
The function is valid if the unit is fitted with tandem or capacity controlled compressors and pressure
transducers. In the event of high pressure alarms, that is, for values over P18 (hysteresis 0.5 bar), the
controller deactivates a load step in the circuit in question and waits 10 seconds. After this interval, if the
alarm is still active, the unit is stopped, otherwise it continues to operate in part load mode. In this situa-
tion, the display shows the message PC1 and/or PC2, depending on the circuit. This condition remains
active until the pressure falls below the value corresponding to the maximum speed of the condenser
fans (F05+F06). Below this value, the unit reactivates the load step that had previously been deactivated.
- Alarm reset
P05: Enables automatic reset for all those alarms that normally feature manual reset (high pressure, low
pressure, flow switch/antifreeze) as per the following table:
P05= 0: (default) high pressure, low pressure and antifreeze (low temperature) with manual reset;
P05= 1: all the alarms with automatic reset;
P05= 2: high pressure and antifreeze (low temperature) manual, low pressure automatic;
P05= 3: high pressure manual, low pressure and antifreeze (low temperature) automatic;
P05= 4: high and low pressure manual, antifreeze (low temperature) automatic;
P05= 5: high and low pressure manual after the third activation in one hour*, antifreeze (low tempera-
ture) automatic;
P05= 6: high and low pressure manual after the third activation in one hour*, antifreeze (low tempera-
ture) manual.
*: the high and low pressure alarms are managed in the same way both for the transducers and the
pressure switches (digital input); if the unit is in standby the count (3 times in one hour) is reset.
- Cooling/Heating logic
P06: If this parameter is set to 1, the operating logic of the Cooling/Heating logic is reversed (from the
keypad, the remote control and the digital input).
Symbol P06= 0 P06= 1
Cooling (Chiller) Heating (heat pump)
Heating (heat pump) Cooling (Chiller)
- Low pressure alarm with pressure probes
P07: P07=0: this function is disabled.
P07=1: if in heat pump mode the evaporator (external exchanger) pressure is less than 1 bar (and if the
presence of the condenser pressure probe is enabled), the low pressure alarm is activated (while still
considering the delay P03).
Note: P07=1 the LP digital inputs in heat pump are ignored.
not managed.
Note: In the event of flow alarms with automatic reset, 10 attempts are made to restart the pump every
90 seconds, for a maximum time of P02; after the 10 attempts, the alarm becomes manual reset. With the
second pump, the attempt consists in switching over the pump that is on, with the same logic.
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