13 Project planning
13.1 Expansion vessel and system pressure
The unit is equipped with and integrated expansion vessel:
▪
Content 18 litres
▪
Inlet pressure 0.75 bar
▶
Use the following table to verify whether an additional expansion vessel should be
installed.
Example
A maximum flow temperature of 50 °C and an installation elevation of 7.5 metres
would result in a maximum system content of 500 litre. An additional expansion vessel
must be installed if this volume is exceeded.
Flow temperature
Height of unit
5 m
7.5 m
10 m
12.5 m
15 m
Maximum admissible total water content
max 40 °C
820 l
700 l
620 l
420 l
300 l
max 50 °C
620 l
500 l
410 l
280 l
190 l
max 60 °C
440 l
360 l
290 l
190 l
140 l
Expansion vessel inlet pressure
The primary pressure is calculated from the static ceiling of the system (e.g.
10 metres is equivalent to 1.0 bar). The static height is measured from the connection
of the expansion vessel to the highest point of the system.
Select 0.5 bar if the static height is less than 5 metres.
▶
Calculate and record inlet pressure.
▶
Check the inlet pressure of the expansion vessel and set to the calculated value,
if necessary.
System pressure
▶
Set the system pressure 0.5 bar above the inlet pressure of the expansion vessel.
Example
10 metre static installation height results in:
expansion vessel inlet pressure 1.0 bar
system pressure 1.5 bar
When installing the hydraulic unit incl. an expansion vessel at the highest point of the
building, e. g. in the loft, set the inlet pressure to 0.5 bar.
Installation and operating instruction
Hydraulic unit WWP L 7 ... L 15
13 Project planning
83279602 • 1/2014-05 • La
55-59
