Anti-Frost Function; Faults - Ariston Nuos Split Flex 150L Manual

Heat pump water heater – OPERATING AND MAINTENANCE INSTRUCTIONS
To be able to operate also on appliances with a two-tier rate system, the control logic calculates the number of average
hours a day during which the power supply is available in the economy mode (HC).
A self-learning function ensures that the appliance reaches the pre-set temperature in the time range during which the
economy rate applies; the maximum limit of hours is determined by the P9 TIME_W parameter; after the initial start-up
(or after switching off the hardware), the default setting is 8 hours. In order to optimize the self-learning function it is
advisable to set AUTO mode.

7.12 Anti-frost function

In any event, if the temperature of the water in the tank falls below 5 °C while the appliance is powered, the heating
element (1000 W) will be automatically activated to heat the water up to 16 °C.

7.13 Faults

As soon as a fault occurs, the appliance enters into the fault mode while the display emits flashing signals and visualises
the error code. The water heater will continue supplying hot water provided the fault affects only one of two the heating
units, by activating the heat pump or heating element.
If the fault involves the heat pump, the symbol "HP" will flash on the screen, while the heating element symbol will flash
if the fault involves this component. If both components are affected, both symbols will flash.
Error
Cause
code
Heating occurs without any water in
E1
the water tank
Excessive temperature of the water
E2
in the tank
E4 Sensor fault – heating element zone
Excessive difference between the
E5 temperatures of the heating
element zone sensors
H2 Circuit in low pressure or fan fault
H3 Compressor fault or gas leak
H4 Evaporator obstructed
H5 Fan fault
H6 Air sensor fault
H7 Evaporator sensor fault
H8 Hot water sensor fault
H9 Active defrost fault
F1 PCB fault
Excessive number of ON/OFF
F2
(RELEASE)
Lack of communication between the
F3
PCB and interface
Heating
Heat pump
element
operation
operation
Turn off the appliance. Verify the causes of the lack of
OFF OFF
water (leakage, faulty hydraulic connections, etc.)
Turn the appliance off then wait until the water
OFF OFF temperature decreases; if the problem persists, contact
the technical assistance service
Check or replace the heating element zone sensors, if
OFF OFF
necessary
OFF OFF Check or replace the sensors, if necessary
Turn off the appliance. Check that the fan is not broken
and that the evaporator is not obstructed. Check whether
ON OFF
the hot gas valve functions properly and replace it if
necessary. Check the evaporator sensor.
Turn off the appliance. Check that the evaporator is not
obstructed. Verify whether the wirings and the compressor
ON OFF
functions properly and/or check for any refrigerant gas
leakages. Check or replace the evaporator sensor.
Turn off the appliance. Check that the evaporator and the
ON ON
external unit casing is not obstructed.
Turn off the appliance. Verify that there are no physical
impediments to the movement of fan blades, check the
ON OFF
wiring of connection with circuit boards. Check the
evaporator sensor.
Check the proper connection of the probe cable between
ON OFF the two units, Verify whether the sensor is properly
connected and positioned, and replace it if necessary.
Check the proper connection of the probe cable between
ON OFF the two units, Verify whether the sensor is properly
connected and positioned, and replace it if necessary.
Verify whether the sensor is properly connected and
ON OFF
positioned, and replace it if necessary
OFF Check that the fan is not broken and that the evaporator is
(if air not obstructed. Check whether the hot gas valve functions
ON
temperature il properly and replace it if necessary. Check that the
below 5°C) external unit casing is not obstructed.
Try turning the appliance off then on again and verify the
OFF OFF
operation of the control boards, if necessary replace it.
Temporarily disconnect the product mains and the
OFF OFF
batteries.
Try turning the appliance off then on again and verify the
OFF OFF operation of the control boards or replace them, if
necessary.
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What to do