Safety and alarms
Safety thermostat cut-out
Error code 69
HIUs configured to support low temperature heating continuously
monitor the safety thermostat controlling the flow temperature.
If the safety thermostat is activated during a general cycle, the heating
circulation pump immediately comes to a stop and the modulating
valve is completely closed.
After the user has removed the block imposed by the safety
thermostat, operation can only be re-enabled when the modulating
valves are completely closed again.
This means that if a domestic water cycle is in progress, the activation
of the shut-off valve will be postponed until the end of that domestic
water cycle.
Corrective action
To restore the operating mode press the manual RESET button.
If the electronic circuit board detects a fault, the display shows the
error code concerned and the symbol
.
Corrective action
Normal operating conditions are restored automatically once the faulty
probe is working properly again (see page 20 - “Temperature probe
replacement”).
Probe fault
If a temperature probe fails, the associated cycle will be stopped
immediately and disabled.
Any requests to run cycles not associated to the previous one will
continue to run normally.
Heating flow probe fault
Error code: 5
Domestic hot water probe fault
Error code: 6
Return probe fault
Error code: 15
The HIU is disabled due to an incorrect connection on the circuit
board front terminals or due to an input from an external device
indicating zero credit.
Corrective action
Check the electrical connections or, in the case of zero credit, top-up
the external device/contact the service supplier.
Heat interface unit disabled
Error code 80
Heating circuit pressure switch fault
Error code 4
The electronic regulator continuously monitors the status of the
pressure switch controlling the water pressure in the heating circuit.
If the pressure switch trips, the heating circulation pump immediately
comes to a stop and the modulating valve is completely closed.
This fault implies the stoppage of the heating cycle only.
Domestic water drawing requests will continue to be served normally.
N.B.
: A low pre-charge value of the expansion vessel can cause a
pressure switch fault.
Corrective action
Return to the operating mode is subordinate to restoration of the
correct water pressure in the secondary heating circuit (see page 9 -
“Filling the user system”).
18
External temperature fault
Error code: 38
