Buderus Logamax plus GB162 Technical Manual page 57

3
V [m
16,00
15,00
14,00
13,00
12,00
11,00
10,00
9,00
8,00
7,00
6,00
5,00
4,00
3,00
2,00
1,00
0,00
Fig. 49 Water treatment limits for multi boiler systems
A Above these curves, use fully desalinated fill water with
≤ 10 μS/cm conductivity; below these curves, untreated
water in accordance with the Drinking Water Ordinance
[Germany] can be used.
From 600 kW upwards, generally use only fully
desalinated fill water.
H Water hardness
W
V Water volume over the service life of the boiler
The current guideline VDI 2035" Prevention of damage in
hot water heating systems" (as of 12/2005) aims to
simplify the application and accommodate the trend
towards more compact appliances with higher heat
transfer rates. The diagram in fig. 48 and fig. 49 enables
the permissible amount of fill and top-up water to be
checked that can be filled during the service life of the
boiler without special treatment, subject to the hardness
(°dH) and the respective boiler output. Special water
treatment measures are required if the water volume lies
above the respective limit curve on the graph.
Suitable measures are as follows:
• Use fully desalinated fill water with a conductivity of
≤ 10 μS/cm. No requirements are made of the pH value
of the fill water. After filling the system, a low-salt
operation results with a conductivity of generally
50 - 100 μS/cm.
• System separation by means of a heat exchanger; only
fill the boiler circuit with untreated water (no chemicals,
no softening).
To prevent the ingress of oxygen into the heating water,
size the diaphragm expansion vessel correctly
( page 65 f.).
When installing pipes that are permeable to oxygen, e.g.
in underfloor heating systems, allow for system separation
by means of a heat exchanger (
6 720 645 821 (2010/09) – Logamax plus GB162
]
≤ 600 kW
≤ 500 kW
≤ 400 kW
≤ 300 kW
≤ 200 kW
≤ 160 kW
≤ 100 kW
700–800 kW
0 5 10
fig. 51, page 59).
A
15 20 25
When modernising existing systems, protect the gas
condensing boiler against sludge build-up from the
existing heating system. For this purpose, the installation
of a dirt trap into the common return line is strongly
recommended. A dirt trap is not required if a new system
is thoroughly flushed prior to filling, and loose particles as
a result of oxygen corrosion can be prevented.
System examples
30
H [°dH]
W
6 720 642 463-36.1il
6
57