Daikin Altherma 3 H MT W - Symptom: the Pressure at the Tapping Point Is Temporarily Unusually High; Symptom: Tank Disinfection Function Is NOT Completed Correctly (AH-Error)

14 | Troubleshooting
Installer reference guide
252
EPRA08~12EAV3+W1 + ETBH/X12EF6V+9W
Daikin Altherma 3 H MT W
4P634885-1 – 2021.03
Possible causes Corrective action
Too much heat pump capacity is used
for heating domestic hot water (applies
only to installations with a domestic hot
water tank)
Check if the Space heating
priority settings have been
configured appropriately:
▪ Make sure that the Space heating
priority has been enabled.
Go to [9.6.1]: Installer
settings > Balancing > Space
heating priority [5‑02]
▪ Increase the "space heating priority
temperature" to activate backup
heater operation at a higher outdoor
temperature.
Go to [9.6.3]: Installer
settings > Balancing > Offset
BSH setpoint [5‑03]
14.3.10 Symptom: The pressure at the tapping point is temporarily unusually high
Possible causes Corrective action
Failing or blocked pressure relief valve. ▪ Flush and clean the complete tank
including the piping between pressure
relief valve and the cold water inlet.
▪ Replace the pressure relief valve.
14.3.11 Symptom: Tank disinfection function is NOT completed correctly (AH-error)
Possible causes Corrective action
The disinfection function was
interrupted by domestic hot water
tapping
Program the start-up of the disinfection
function when the coming 4hours NO
domestic hot water tapping is expected.
Large domestic hot water tapping
happened recently before the
programmed start-up of the disinfection
function
If in [5.6] Tank > Heat up mode the
mode Reheat only or Schedule +
reheat is selected, it is recommended
to program the start-up of the
disinfection function at least 4hours
later than the last expected large hot
water tapping. This start-up can be set
by installer settings (disinfection
function).
If in [5.6] Tank > Heat up mode the
mode Schedule only is selected, it is
recommended to program a Eco action
3hours before the scheduled start-up
of the disinfection function to preheat
the tank.
The disinfection operation was stopped
manually: [C.3] Operation > Tank was
turned off during disinfection.
Do NOT stop tank operation during
disinfection.