Changing The Pre-Pressure Of The Expansion Vessel - Rotex HPSU Bi-Bloc Ultra Series Installer's Reference Manual

a b c d f
T1
M1
e f
FHL1
a Outdoor unit
b Indoor unit
c Heat exchanger
d Backup heater
e Pump
f Shut-off valve
g Collector (field supply)
h Overpressure bypass valve (delivered as accessory)
FHL1...3 Floor heating loop (field supply)
T1...3 Individual room thermostat (optional)
M1...3 Individual motorised valve to control loop FHL1...3 (field
supply)
Maximum water volume
Use the following graph to determine the maximum water volume for
the calculated pre-pressure.
a
2.4
2
1.5
1
0.5
0.3
20 50 100 150
a Pre-pressure (bar)
b Maximum water volume (l)
Example: Maximum water volume and expansion vessel pre-
pressure
Installation
height
≤200 l
(a)
difference
≤7 m No pre-pressure
adjustment is required.
RRGA04~08DAV3 + RHBX04+08DA
ROTEX HPSU Bi-Bloc Ultra
4P495262-1B – 2019.10
g h
T2 T3
M2 M3
FHL2
FHL3
200 250 290
Water volume
>200 l
Do the following:
▪ Decrease the pre-
pressure according to
the required installation
height difference. The
pre-pressure should
decrease by 0.1 bar for
each metre below 7 m.
▪ Check if the water
volume does NOT
exceed the maximum
allowed water volume.
Installation
height
(a)
difference
>7 m Do the following:
▪ Increase
pressure according to
the
installation
difference.
pressure
increase by 0.1 bar for
each metre above 7 m.
▪ Check if the water
volume
exceed the maximum
allowed water volume.
(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.
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).
Minimum required flow rate
12 l/min
See the recommended procedure as described in
commissioning" [ 4 80].
during
b
6.4.4 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.
Changing the pre-pressure of the expansion vessel should be done
by releasing or increasing nitrogen pressure through the Schrader
valve of the expansion vessel.
6 Preparation
Water volume
≤200 l >200 l
The expansion vessel of
the indoor unit is too
the pre-
small for the installation.
In this case, it is
required
recommended to install
height
an extra vessel outside
The pre-
the unit.
should
does NOT
"9.4 Checklist
Installer reference guide
27