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12. TROUBLESHOOTING
This section provides useful information for diagnosing and correcting certain troubles which may occur in the unit.
LCD display off
If after touching the keys, the display does not switch on, check that the board is connected to the power supply. Check for the supply voltage using a digital multimeter.
If there is no voltage present, check the wiring.
If there is a suitable voltage (Range 195 – 253 Vac), check the state of the fuse (3.15AL@230VAC). The fuse is located on the board. To access it, see "fig. 60 -" on
page 85.
12.1 General guidelines
Before starting the troubleshooting procedure, carry out a thorough visual inspection of the unit and look for obvious defects such as loose connections or defective
wiring.
WARNING
When carrying out an inspection on the switch box of the unit, always make sure that the main switch of the unit is
switched off.
When a safety device was activated, stop the unit and find out why the safety device was activated before resetting
it. Under no circumstances can safety devices be bridged or changed to a value other than the factory setting. If the
cause of the problem cannot be found, call your local dealer.
If the pressure relief valve is not working correctly and is to be replaced, always reconnect the flexible hose attached
to the pressure relief valve to avoid water dripping out of the unit!
12.2 General symptoms
Symptom 1: the unit is turned on but is not heating or cooling as expected
Possible causes
Some parameter settings are incorrect.
The water flow is too low.
The volume of water in the installation is too low.
Symptom 2: the unit is turned on but the compressor does not start (system heating or DHW heating)
Possible causes
The unit could be operating outside its operating
range (the water temperature is too low).
Symptom 3: the pump is noisy (cavitation)
Possible causes
There is air in the system.
The pump input water pressure is too low.
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EN
Corrective action
Check the parameters
T4HMAX, T4HMIN in heating mode.
T4CMAX, T4CMIN in cooling mode
T4DHWMAX, T4DHWMIN in DHW mode.
Make sure that all the shut-off valves in the hydraulic circuit are open.
Check if the water filter is clogged.
Check that there is no air in the hydraulic circuit.
Check the water pressure. The water pressure must be > 1 bar (with cold system water).
Make sure that the expansion vessel is not broken.
Check that the pressure drop in the hydraulic circuit is not too high for the pump.
Make sure that the volume of water in the installation is higher than the minimum value requested
Corrective action
If the water temperature is low, the system uses the reserve system electric heater to reach the first minimum water
temperature (12°C).
Check that the reserve system electric heater power supply is correct.
Check that the electric protection of the reserve system electric heater is correct.
Check that the thermal cut-off switch of the reserve system electric heater is not activated.
Check that the reserve system electric heater meters are not faulty.
Corrective action
Bleed the air.
Check the water pressure.
The water pressure must be > 1 bar (measured with cold water).
Make sure that the expansion vessel is not broken or empty.
Check that the preload of the expansion vessel is correct
Cod. 3542B230 - Rev. 00 - 02/2022
OMNIA S HYBRID H 3.2
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