E-
19
ENGLISH
Pipe work (Continued)
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.
Installation height
difference
(a)
Water volume
< 220 Litres
> 220 Litres
<7m
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
>7m
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 0m.
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
Water volume (Litre) in total system including pipes
[L
it
]
50
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
100
150
200
250
300
350
400
Operation range
Expansion Vessel capacity (Liter)
Norminal
❈
Water volume of total system for reliable performance is minimum 50 litres.
NH080PHXEAHydro unit_IM_E 32659-1.indd 19
2010-07-28 ｿﾀﾈﾄ 8:59:27
