Daikin Altherma 3 H MT F - Changing the Pre-Pressure of the Expansion Vessel

8 | Piping installation
Installer reference guide
88
EPRA08~12EAV3+W1 + ETVH12SU18+23EA6V
Daikin Altherma 3 H MT F
4P644482-1 – 2021.03
Installation
height
difference
(a)
Water volume
≤190l >190l
>7m Do the following:
▪ Increase the pre-pressure
according to the required
installation height
difference. The pre-pressure
should increase by 0.1 bar
for each metre above 7 m.
▪ Check if the water volume
does NOT exceed the
maximum allowed water
volume.
The expansion vessel of the
indoor unit is too small for the
installation. In this case, it is
recommended to install an
extra vessel outside the unit.
(a)
This is the height difference (m) between the highest point of the water circuit and the
indoor unit. If the indoor unit is at the highest point of the installation, the installation
height is 0m.
Minimum flow rate
Check that the minimum flow rate in the installation is guaranteed in all conditions.
This minimum flow rate is required during defrost/backup heater operation. For
this purpose, use the overpressure bypass valve delivered with the unit, and
respect the minimum water volume.
Minimum required flow rate
20l/min
NOTICE
If glycol was added to the water circuit, and the temperature of the water circuit is
low, the flow rate will NOT be displayed on the user interface. In this case, the
minimum flow rate can be checked by way of the pump test (check that the user
interface does NOT display error 7H).
NOTICE
When circulation in each or certain space heating loops is controlled by remotely
controlled valves, it is important that the minimum flow rate is guaranteed, even if all
valves are closed. In case the minimum flow rate cannot be reached, a flow error 7H
will be generated (no heating or operation).
See the recommended procedure as described in "11.4 Checklist during
commissioning"[4228].
8.1.4 Changing the pre-pressure of the expansion vessel
NOTICE
ONLY a licensed installer may adjust the pre-pressure of the expansion vessel.
The default pre-pressure of the expansion vessel is 1 bar. When it is required to
change the pre-pressure, take following guidelines into account:
▪ Only use dry nitrogen to set the expansion vessel pre-pressure.
▪ Inappropriate setting of the expansion vessel pre-pressure will lead to
malfunction of the system.