5.
Commissioning
5.1 Water quality
26
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COMMISSIONING
Heating Water
The European Standard EN 14868 and the
directive VDI 2035 must be observed.
In particular, attention must be paid to the following stipu-
lations:
•
Hoval boilers and calorifi ers are designed for heating
plants without signifi cant oxygen intake (plant type I ac-
cording to EN 14868).
• Plants with
- continuous oxygen intake (e.g. underfloor heating
systems without diffusion proof plastic piping) or
- intermittent oxygen intake (e.g. where frequent refill-
ing is necessary)
must be equipped with
separate circuits.
•
Treated fi lling and replacement water must be tested at
least 1x yearly. According to the inhibitor manufacturer‘s
instructions, more frequent testing may be necessary.
•
A refi lling is not necessary if the quality of the heating
water in existing installations (e.g. exchange of boiler)
conforms to VDI 2035.
The Directive VDI 2035 applies equally to the replace-
ment water.
• New and if applicable existing installations need to be
adequately cleaned and fl ushed befor being fi lled. The
boiler may only be fi lled after the heating system has
been fl ushed!
•
Parts of the boiler / calorifi er which have contact with
water are made of ferrous materials and stainless steel.
• On account of the danger of stress cracking corrosion
in the stainless steel section of the boiler the chloride,
nitrate and sulphate content of the heating water must
not exceed 50 mg/l.
• The pH value of the heating water should lie between
8.3 and 9.5 after 6-12 weeks of heating operation.
Filling and replacement water
• For a plant using Hoval boilers untreated drinking water
is generally best suited as heating medium, i.e. as fi ll-
ing and replacement water. However, as not all drinking
water is suitable for use as as fi lling and replacement
water the water quality must fulfi l the standard set in
VDI 2035. Should the mains water available not be
suited for use then it must be desalinated and/ or be
treated with inhibitors. The stipulations of EN 14868
must be observed.
•
In order to maintain a high level of boiler effi ciency and
to avoid overheating of the heating surfaces the values
given in the table should not be exceeded (dependent
on boiler performance ratings - for multi-boiler plants
rating of smallest boiler applies - and on the water con-
tent of the plant).
•
The total amount of fi lling and replacement water which
is used throughout the total service life of the boiler
must not exceed three times the water capacity of the
plant.
Maximum filling capacity based on VDI 2035
Total hardness of the fi lling water up to ...
[mol/m
3
]
1
<0,1
0,5
1
1,5
2
2,5
3
>3,0
f°H
<1
5
10
15
20
25
30
>30
d°H
<0,56
2,8
5,6
8,4
11,2
14,0
16,8
>16,8
e°H
<0,71
3,6
7,1
10,7
14,2
17,8
21,3
>21,3
~mg/l
<10
50,0
100,0
150,0
200,0
250,0
300,0
>300
Conductance
2
<20
100,0
200,0
300,0
400,0
500,0
600,0
>600
Boiler size of the
individual boiler
maximum fi lling quantity without desalination
to 50 kW
NO REQUIREMENT
20 l/kW
1
Sum of alkaline earths
2
If the conductance in µS/cm exceeds the tabular value an analysis of the water is necessary.
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