Sizing Expansion Vessels
Expansion vessel volume must fit the local system water volume.
To size an expansion vessel both for the heating and cooling circuits 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***-*M*ED model, provide and install a suitable primary-
side expansion vessel and additional 3 bar rated pressure relief valve in the field
as the model does not come fitted with a primary-side expansion vessel.
ε × G
P ¹ + 0.098
P ² + 0.098
Graph to the right is for the following values
4.4 Electrical Connection
All electrical work should be carried out by a suitably qualified technician. Failure
to comply with this could lead to electrocution, fire, and death. It will also invali-
date product warranty. All wiring should be according to national wiring regula-
Earth leakage circuit breaker for booster heater
Terminal block 1
< 1 phase >
< Figure 4.4.1 >
V : Necessary expansion vessel volume [L]
: 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]
: at 70°C = 0.0229
P ¹ : 0.1 MPa
P ² : 0.3 MPa
*A 30% safety margin has been added.
< 3 Phase >
Expansion vessel sizing
System water volume [L]
The hydrobox can be powered in two ways.
1. Power cable is run from the outdoor unit to the hydrobox.
2. Hydrobox has independent power source.
Connections should be made to the terminals indicated in the figures to the left
below depending on the phase.
Booster heater and immersion heater should be connected independently from
one another to dedicated power supplies.
Locally supplied wiring should be inserted through the inlets situated on the
base of the hydrobox. (Refer to <Table 3.4>.)
Wiring should be fed down the left hand side of the control and electrical box
and clamped in place using clips provided.
The wires should be fixed with the cable straps as below.
2 Output wires
3 Indoor-Outdoor wire
6 Power line (B.H.)
7 Signal input wires/ Wireless receiver
(option) wire (PAR-WR51R-E)
Connect the outdoor unit – hydrobox connecting cable to TB1.
Connect the power cable for the booster heater to ECB1.
• Make sure that ECB1 is ON.