Daikin Altherma EHYHBH05A Series - Symptom: the Compressor Does NOT Start (Space Heating or Domestic Water Heating); Symptom: the Pump Is Making Noise (Cavitation)

15 | Troubleshooting
Installer reference guide
217
EVLQ05+08CA + EHYHBH05A + EHYHBH/X08A + EHYKOMB33AA
Daikin Altherma hybrid heat pump
4P355634-1G – 2022.09
15.3.2 Symptom: The compressor does NOT start (space heating or domestic water heating)
Possible causes Corrective action
The unit must start up out of its
operation range (the water
temperature is too low)
If the water temperature is too low, the
unit uses the gas boiler to reach the
minimum water temperature first
(15°C).
Check and make sure that:
▪ The power supply to the gas boiler is
correctly wired.
▪ The communication cable between
the gas boiler and the indoor unit is
properly mounted.
If the problem persists after you have
conducted all of the above checks,
contact your dealer.
The preferential kWh rate power supply
settings and electrical connections do
NOT match
This should match with the connections
as explained in "9.1About connecting
the electrical wiring"[4110] and
"9.3.2To connect the main power
supply of the indoor unit"[4118].
The preferential kWh rate signal was
sent by the electricity company
Wait for the power to return (2 hours
max.).
Domestic hot water (including
disinfection) and space heating
operation are scheduled to start at the
same time.
Change the schedule to not start both
operation modes at the same moment.
15.3.3 Symptom: The pump is making noise (cavitation)
Possible causes Corrective action
There is air in the system Purge air manually (see "To perform a
manual air purge"[4198]) or use the
automatic air purge function (see "To
perform an automatic air
purge"[4199]).
The water pressure at the pump inlet is
too low
Check and make sure that:
▪ The water pressure is >1bar.
▪ The pressure sensor of the gas boiler
is not broken.
▪ The expansion vessel is NOT broken.
▪ The pre-pressure setting of the
expansion vessel is correct (see
"8.5.4 Changing the pre-pressure of
the expansion vessel"[4102]).