ENGLISH-20
Pipe work
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:
f
f
Use only dry nitrogen to set the expansion vessel pre-pressure .
f
f
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 .
[Lit]
50
100
150
200
250
300
350
400
14 .00
12 .00
10 .00
8 .00
6 .00
4 .00
2 .00
0 .00
Water volume (Litre) in total system including pipes
Operation range
Norminal
Expansion Vessel capacity (Liter)
• Water volume of total system for reliable performance is minimum 50 liters .
CAUTION
Installation height
difference
a)
Water volume
< 220 Litres
> 220 Litres
< 7 m
No pre-pressure adjustment required .
Actions required:
• Pre-pressure must be decreased, calculate
according to “Calculating the pre-pressure of
the expansion vessel” .
• Check if the water volume is lower than
maximum allowed water volume
> 7 m
Actions required:
• Pre-pressure must be increased, calculate
the appropriate value following by
“Calculating the pre-pressure of the
expansion vessel” .
• Check if the water volume is lower than
maximum allowed water volume
Expansion vessel of the unit too small for the
installation .
a) Installation height difference: height difference(m) between the highest point of the water circuit and the indoor unit . If
the indoor unit is located at the highest point of the installation, the installation height is considered 0 m .
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
