Daikin EBHQ008BBV3 [14/24] Setting the pre pressure of the expansion vessel
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Daikin EBHQ008BBV3 [14/24] Setting the pre pressure of the expansion vessel

Daikin EBHQ008BBV3 [14/24] Setting the pre pressure of the expansion vessel
Installation manual
12
EBHQ006+008BBV3
Unit for air to water heat pump system
4P347825-1A – 2013.04
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 unit is too small
for the installation.
Example 1
The outdoor unit is installed 5 m 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 outdoor unit is installed 4 m below the highest point in the water
circuit. The total water volume in the water circuit is 190 l.
Result:
■ Since 190 l is higher than 170 l, the pre-pressure must be
decreased (see table above).
■ The required pre-pressure is:
Pg = (H/10 + 0.3) bar = (4/10 + 0.3) bar = 0.7 bar
■ The corresponding maximum water volume can be read from
the graph: approximately 200 l.
■ Since the total water volume (190 l) is below the maximum water
volume (200 l), the expansion vessel suffices for the installation.
10.3. Setting the pre-pressure of the expansion vessel
When it is required to change the default pre-pressure of the
expansion vessel (1 bar), keep in mind the following guidelines:
■ Use only dry nitrogen to set the expansion vessel pre-pressure.
■ Inappropriate setting of the expansion vessel pre-pressure will
lead to malfunction of the system. Therefore, the pre-pressure
should only be adjusted by a licensed installer.
10.4. Connecting the water circuit
Water connections must be made in accordance with all applicable
legislations and the outlook drawing delivered with the unit,
respecting the water in- and outlet.
If dirt gets in the water circuit, problems may occur. Therefore, always
take into account the following when connecting the water circuit:
■ Use clean pipes only.
■ Hold the pipe end downwards when removing burrs.
■ Cover the pipe end when inserting it through a wall so that no
dust and dirt enter.
■ Use a good thread sealant for the sealing of the connections.
The sealing must be able to withstand the pressures and
temperatures of the system, it must also be resistant to the used
glycol in the water.
■ When using non-brass metallic piping, make sure to insulate
both materials from each other to prevent galvanic corrosion.
■ Because brass is a soft material, use appropriate tooling for
connecting the water circuit. Inappropriate tooling will cause
damage to the pipes.
■ Increasing the distance between shut-off valves is necessary for
ease of installation.
Installation example
1 To secure the piping of the unit
2 To connect the shut-off valve
3 Water outlet
4 Water intlet
5 Round socket 2x 1" FBSP (field supply)
6 1" MBSP pipe end (field supply)
= Pre-pressure
= Maximum water volume
A = System without glycol
B = System with 25% propyleen glycol
C = With EKMBUH unit only
0.3
0.5
1
1.5
2
2.5
100
500
10
150 200 250 300 350 400 450
maximum water volume [l]
pre-pressure [bar]
B
A C
NOTICE
Be careful not to deform the unit piping by using excessive
force when connecting the piping.
1 5
2
4
3
6
4 3

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