10
Recommendation
Commission Viessmann Industrial Service (for contact
details, see page 33) or another contractor to carry
out the relevant measures.
Flow temperatures
>
100 °C (VdTÜV MB 1466)
Operating with circulating water with low salt con-
tent
Note
Only use fill and top-up water with low salt con-
tent, e.g. desalinated water, permeate or condensate.
Systems using mixed condensation:
These systems generally create water with a low salt
content if no boiler water is fed into the system for
alkalisation.
Operation with saline circulating water
Required properties for the fill and top-up water:
■
Low salt content
■
Free of alkaline earths and softened
Boiler water properties
Requirements
Salt content
Low salt
Saline
Electrical conductivity at 25 °C
μS/cm
10 to 30
>
30 to 100
>
100 to 1500
General properties
Clear, free of sediment
pH value
■
At 25 °C
■
In accordance with the Drinking Water Ordi-
nance/Drinking Water Treatment Ordinance
9 - 10
9 - 10.5
9 - 10.5
≤
9.5
≤
9.5
≤
9.5
Oxygen (O
2
)
*1
mg/l
< 0.1
< 0.05
< 0.02
*2
Alkaline earths (Ca, Mg)
mmol/l
< 0.02
< 0.02
< 0.02
Phosphate
■
PO
4
mg/l
< 5
< 10
< 15
■
In accordance with the Drinking Water Ordi-
nance/Drinking Water Treatment Ordinance
mg/l
≤
7
≤
7
≤
7
■
For Viessmann hot water boilers
mg/l
< 2.5
< 5
< 15
Use of oxygen binders:
Sodium sulphite (Na
2
SO
3
)
*3
mg/l
–
–
< 10
Tab. 2
Preventing water side corrosion
General
Oxygen is introduced into the heating system with the
fill water when the system is filled initially and during
any subsequent top-ups.
This oxygen reacts with materials without causing any
damage to the system.
After a certain time in operation, the water in the sys-
tem turns black because there is no more free oxygen
present in the system.
As there is now no oxygen in the heating water, the
materials of the heating system and boiler are protec-
ted from corrosion on the heating water side.
!
Please note
The ingress of oxygen can cause damage as a
consequence of oxygen corrosion.
Prevent the ingress of oxygen by means of suit-
able measures.
*1
Lower values are possible in continuous operation.
*2
If using permissible inorganic corrosion inhibitors in the circulating water, oxygen concentrations up to 0.1 mg/l are possible
*3
If using other permissible products, follow the respective manufacturer's guidelines.
Water quality
Standard values for water quality
(cont.)
6152553
Service
Summary of Contents for M22
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