6 Preparation
Installer reference guide
26
RRLQ004~008CA + RHBH/X04+08CB
ROTEX HPSU low temperature Bi‑bloc
4P384979-1C – 2017.04
▪ You might need to adjust the pre-pressure of the expansion
vessel.
Minimum water volume
Check that the total water volume in the installation is minimum
10 litre, the internal water volume of the indoor unit NOT included.
INFORMATION
In critical processes, or in rooms with a high heat load,
extra water might be required.
NOTICE
When circulation in each space heating/cooling loop is
controlled by remotely controlled valves, it is important that
the minimum water volume is guaranteed, even if all of the
valves are closed.
FHL1
FHL2
FHL3
M1
T1
M2
T2
M3
T3
f
d
c
b
a
f
g
h
e
a
Outdoor unit
b
Indoor unit
c
Heat exchanger
d
Backup heater
e
Pump
f
Shut-off valve
g
Collector (field supply)
h
By-pass valve (field supply)
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.
0.3
0.5
1
1.5
2
2.5
100
50
0
10
150
200
250
300
350
400
450
a
b
a
Pre-pressure (bar)
b
Maximum water volume (l)
Example: Maximum water volume and expansion vessel pre-
pressure
Installation
height
difference
(a)
Water volume
≤280 l
>280 l
≤7 m
No pre-pressure
adjustment is required.
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.
>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 (required during defrost/backup
heater operation) in the installation is guaranteed in all conditions.
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/operation).
Minimum required flow rate during defrost/backup heater
operation
04+08 models
12 l/min
11+16 models
15 l/min
See the recommended procedure as described in
"9.4 Checklist
during commissioning" on page 73
.
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.
When changing the default pre-pressure of the expansion vessel
(1 bar) is required, 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.
