29
Be careful not to deform the unit’s piping by
using excessive force when connecting the
piping. Deforming the piping can cause the unit
to malfunction.
CAUTION
Selecting the additional expansion vessel
If the expansion vessel of the unit is too small for the
installation, an additional expansion vessel is needed.
calculate the pre-pressure of the expansion vessel:
Pg(bar)=(H(m)/10+0.3) bar
the expansion vessel equipped in the unit should
adjust the pre- pressure also.
calculate the volume needed of the additional expan-
sion vessel:
V1=0.0693*Vwater/(2.5-Pg)-V0
Vwater is volume of water in the system, V0 is volume
of expansion vessel which the unit is equipped(8L).
9.4.3 Water circuit connection
Water connections must be made correctly in
accordance with labels on the outdoor unit, with respect
to the water inlet and water outlet.
Use clean pipes only.
Hold the pipe end downwards when removing burrs.
Cover the pipe end when inserting it through a wall to
prevent dust and dirt entering.
Use a good thread sealant for sealing the connec-
tions. The sealing must be able to withstand the
pressures and temperatures of the system.
When using non-copper metallic piping, be sure to
insulate two kind of materials from each other to
prevent galvanic corrosion.
If air, moisture or dust gets in the water circuit, problems
may occur. Therefore, always take into account the
following when connecting the water circuit:
For copper is a soft material,
use appropriate tools for
connecting the water circuit.
Inappropriate tools will cause
damage to the pipes.
Pre-pressure = pre-pressure of the expansion vessel
Maximum water volume = maximum water volume in the
system
A1 System without glycol
A2 System without 25% propylene glycol
Example 1
：
The unit is installed 5m below the highest point in the
water circuit. The total water volume in the water circuit is
100 L. In this example, no action or adjustment is
required.
Example 2
：
The unit is installed at the highest point in the water
circuit. The total water volume in the water circuit is 250
L.
Result:
Since 250 L is more than 230 L, the pre-pressure
must be decreased (see table above).
The required pre-pressure is: Pg(bar) =
(H(m)/10+0.3) bar = (0/10+0.3) bar = 0.3 bar
The corresponding maximum water volume can be
read from the graph: approximately 310L.
Since the total water volume (250L) is below the
maximum water volume (310L), the expansion vessel
suffices for the installation.
Setting the pre-pressure of the expansion vessel
When it is required to change the default pre-pressure of
the expansion vessel (1.0 bar), following guidelines:
Use only dry nitrogen to set the expansion vessel
pre-pressure.
Inappropriate setting of the expansion vessel
pre-pressure will lead to malfunctioning of the
system. Pre-pressure should only be adjusted by a
licensed installer.
Determine the calculated pre-pressure (Pg) for the
corresponding maximum water volume using the
graph below.
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 unit is too small for
the installation.
NOTE
Never use Zn-coated parts in the water
circuit. Excessive corrosion of these parts
may occur as copper piping is used in the
unit's internal water circuit.
When using a 3-way valve in the water circuit.
Preferably choose a ball type 3-way valve to
guarantee full separation between the
domestic hot water and floor heating water
circuit.
When using a 3-way valve or a 2-way valve in
the water circuit. The recommended
maximum changeover time of the valve
should be less than 60 seconds.
The unit is only to be used in a closed water
system. Application in an open water circuit can
lead to excessive corrosion of the water piping:
0.3
0.8
1.3
1.8
2.3
2.8
3.3
0
50
100
150
200
250
300
350
Pre-p
re
ss
ur
e
[b
ar
]
Max. water volume [L]
A1
A2
