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OMNIA S HYBRID H 3.2
Symptom 4: the water pressure relief valve opens
Possible causes
The expansion vessel is broken or empty
The filling water temperature in the system is
greater than 3 bar.
Symptom 5: the water pressure relief valve leaks
Possible causes
Dirt has blocked the water safety valve.
Symptom 6: room heating capacity insufficient when external temperatures are low
Possible causes
The reserve system electric heater operation is
not enabled.
A high heating capacity has been requested in
DHW mode or some parameters are not cor-
rectly set (only applicable to installation with DHW
heater).
Symptom 7: heat mode can't change to DHW mode immediately
Possible causes
The volume of the DHW boiler is too small and
the position of the water temperature probe is not
high enough
Symptom 8: DHW mode can't change to Heat mode immediately
Possible causes
DHW boiler coil surface insufficient
The system heating load is reduced
The disinfection function is enabled but without
TBH
Manual switch on of the FAST DHW function, in
this case the heat pump can switch to system
heating mode only after reaching the DHW heater
setpoint
DHW mode priority
Symptom 9: the DHW mode heat pump stops working but the setpoint is not reached, the system requests heat but unit stays in DHW mode
Possible causes
DHW boiler coil surface insufficient
TBH or AHS not available
Corrective action
Replace the expansion vessel. Refill the expansion vessel.
Make sure that the filling water temperature in the system is about 1 or 2 bar.
Corrective action
Check that the safety valve is working correctly by turning the red knob on the valve anti-clockwise:
• If you don't hear a metallic noise, contact the local technical support service.
• If the water continues to leak from the unit, close the water input and output check valves and then, contact the local
technical support service.
Corrective action
Check that the system electric heater is enabled "9.3.2 Heat pump service menu" on page 60.
Check if the reserve system electric heater thermal cut-off switch is enabled or not.
Check if the DHW electric heater is working, the back-up heater and DHW electric heater cannot operate at the same time.
Check that "t_DHWHP_MAX" and "t_DHWHP_RESTRICT" re configured properly:
• Check that "HOT WATER PRIORITY" is disabled in the user interface.
• Enable "T4_TBH_ON" in the user interface / FOR SERVICEMAN to activate the electric heating element of the DHW
boiler for heating domestic hot water.
Corrective action
Set the "dT1S5" parameter on the maximum value.
Check that the "Dhw Priority" is =1 (DHW priority enabled).
If the parameter "Dhw Priority" =0, set the "t_DHWHP_RESTRICT" parameter on the minimum value.
Set dT1SH to 2°C.
Enable the DHW electric heater resistance (TBH, see "Dip switch setting on indoor unit hydronic board" on page 63).
If TBH and AHS are not available, try changing the position of the T5 probe by moving it higher.
Corrective action
Set the parameter "Dhw Priority" =0 and set the parameter "t_DHWHP_MAX" to the minimum value (the recommended
value is 60 min).
Normal, heating not required
Disable the disinfection function
Add TBH or AHS for the DHW mode and for the anti-legionella disinfection
Manual disabling of the FAST DHW function
If the parameter "Dhw Priority" =1, the heat pump can switch to system heating mode only after reaching the DHW set-
point.
Corrective action
Set the parameter "Dhw Priority" =0 and set the parameter "t_DHWHP_MAX" to the minimum value (the recommended
value is 60 min).
If the parameter "Dhw Priority" =1, the heat pump can switch to system heating mode only after reaching the DHW set-
point.
If the parameter "Dhw Priority" =0, the heat pump will remain in DHW mode for the time defined by the "t_DHWHP_MAX"
parameter
Add TBH or AHS for the DHW mode
Cod. 3542B230 - Rev. 00 - 02/2022
73
EN
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