Filling The System (Primary Circuit); Sizing Expansion Vessels - Mitsubishi Electric ecodan ERST20 series Installationshandbuch

4
installation

Filling the System (Primary Circuit)

1. Check all connections including factory fitted ones are tight.
2. Insulate pipework between cylinder unit and outdoor unit.
3. Thoroughly clean and flush, system of all debris. (see section 4.2 for instruction.)
4. Fill cylinder unit with potable water. Fill primary heating circuit with water and
suitable anti-freeze and inhibitor as necessary. Always use a filling loop with
double check valve when filling the primary circuit to avoid back flow
contamination of water supply.
• Anti-freeze should always be used for packaged model systems (see
section 4.2 for instruction). It is the responsibility of the installer to decide
if anti-freeze solution should be used in split model systems depending
on each site's conditions. Corrosion inhibitor should be used in both split
model and packaged model systems.
Figure 4.3.3 shows freezing temperature against anti-freeze concentration.
This figure is an example for FERNOX ALPHI-11. For other anti-freeze,
please refer to relevant manual.
• When connecting metal pipes of different materials insulate the joints to
prevent a corrosive reaction taking place which will damage the pipework.
5. Check for leakages. If leakage is found, retighten the nut onto the connections.
6. Pressurise system to 1 bar.
7. Release all trapped air using air vents during and following heating period.
8. Top up with water as necessary. (If pressure is below 1 bar)

Sizing expansion Vessels

Expansion vessel volume must fit the local system water volume.
To size an expansion vessel for the heating circuit the following formula and
graph can be used.
When the necessary expansion vessel volume exceeds the volume of an built-in
expansion vessel, install an additional expansion vessel so that the sum of the
volumes of the expansion vessels exceeds the necessary expansion vessel
volume.
* For installation of an E*ST20*-*M*EC model, provide and install an expansion
vessel in the field as the model does not come fitted with an expansion vessel.
ε × G
V =
P ¹ + 0.098
1 −
P ² + 0.098
Where;
V : Necessary expansion vessel volume [L]
ε : Water expansion coefficient
G : Total volume of water in the system [L]
P ¹ : Expansion vessel setting pressure [MPa]
P ² : Max pressure during operation [MPa]
Graph to the right is for the following values
ε : at 70 °C = 0.0229
P ¹ : 0.1 MPa
P ² : 0.3 MPa
*A 30% safety margin has been added.
5
0
-5
-10
-15
-20
-25
0 10 20
Anti-freeze concentration [%]
<Figure 4.3.3>
expansion vessel sizing
25
20
15
10
5
0
0 50 100 150
System water volume [L]
<Figure 4.3.4>
30 40 50
200 250 300 350 400
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