Installation manual
13
EKHBRD011~0Y17
Indoor unit for air to water heat pump system
4P402191-1B – 2017.09
Checking the water volume and expansion vessel
pre-pressure
The unit is equipped with an expansion vessel of 12 litre which has a
default pre-pressure of 1 bar.
To assure proper operation of the unit, the pre-pressure of the
expansion vessel might need to be adjusted and the minimum and
maximum water volume must be checked.
1
Check that the total water volume in the installation, excluding
the internal water volume of the unit, is 20 l minimum.
2
Using the table and instructions below, determine if the
expansion vessel pre-pressure requires adjustment and
determine if the total water volume in the installation is below the
maximum allowed water volume.
Calculating the pre-pressure of the expansion vessel
The pre-pressure (Pg) to be set depends on the maximum installation
height difference (H) and is calculated as below:
Pg=(H/10+0.3) bar
Checking the maximum allowed water volume
To determine the maximum allowed water volume in the entire circuit,
proceed as follows:
1
Determine for the calculated pre-pressure (Pg) the
corresponding maximum water volume using the graph below.
2
Check that the total water volume in the entire water circuit is
lower than this value.
If this is not the case, the expansion vessel inside the indoor unit is
too small for the installation.
In most applications this minimum water volume will have a
satisfying result.
In critical processes or in rooms with a high heat load
though, extra water volume might be required.
When circulation in each space heating/radiator loop is
controlled by remotely controlled valves, it is important that
this minimum water volume of 20 l is kept even if all the
valves are closed.
Example
1
Outdoor unit
10
Radiator (field supply)
2
Indoor unit
11
Electronic expansion
valve
3
Refrigerant heat
exchanger
C1
Remote controller
4
Water heat exchanger
M1...M3
Individual motorized valve
to control loop radiators
(field supply)
5
Compressor
6
Pump
T1...T3
Individual room
thermostat (field supply)
7
Shut-off valve
8
Collector (field supply)
A
Installation space
9
By-pass valve
(field supply)
B
Living room
7 7 8
4
3
2
9
1
6
10
5
T3
T2
A
B
C1
M3
M2
M1
T1
11
11
Installation
height
difference
(a)
(a) Installation height difference: height difference (m) between the highest point
of the water circuit and the indoor unit. If the indoor unit is located at the
highest point of the installation, the installation height is considered 0 m.
Water volume
65°C
≤
270 l
80°C
≤
180 l
65°C >270 l
80°C >180 l
≤
7 m
No pre-pressure adjustment
required.
Actions required:
• pre-pressure must be
decreased, calculate
according to
the pre-pressure of the
expansion vessel"
• check if the water volume
is lower than maximum
allowed water volume
(use graph below)
>7 m
Actions required:
• pre-pressure must be
increased, calculate
according to
the pre-pressure of the
expansion vessel"
• check if the water volume
is lower than maximum
allowed water volume
(use graph below)
Expansion vessel of the unit
too small for the installation.
= pre-pressure
= maximum water volume
= increase pre-pressure vessel volume
= decrease pre-pressure vessel volume
0.3
0.5
1
0.0
1.5
2
2.5
100
50
0
20
150
200
250
300
350
400
450
maximum water volume [l]
pre-pressure [bar]
80
80
°
C
65
65
°
C
80
°
C
65
°
C
4PEN402191-1B_2017_09.book Page 13 Friday, October 6, 2017 7:03 PM
