22
4 205 254 / 03
Commissioning
The following systems must be equipped with
separate circuits:
Systems with a specific water content of over 50
•
ltr./kW for the boiler (in cascades, for the smallest
boiler)
Plants with
•
-
continuous
oxygen intake (e.g. underfloor heat-
ing systems without diffusion proof plastic piping
or open expansion tank) or
-
intermittent
oxygen intake (e.g. where frequent
refilling is necessary)
Older systems with formation of sludge in which in-
•
creased concentrations of the metals which come
into contact with the water are found in the existing
heating water.
Systems operated with softened water.
•
Treated heating water must be tested at least 1x
•
yearly, according to the inhibitor manufacturer‘s
instructions, more frequent testing may be neces-
sary.
A refilling is not necessary if the quality of the heat-
•
ing water in existing installations (e.g. exchange of
boiler) conforms to VDI 2035. The Directive VDI
2035 applies equally to the replacement water.
New and if applicable existing installations must
•
be adequately cleaned and flushed before being
recharged! The boiler may only be filled after the
heat ing system has been flushed.
Parts of the boiler which have contact with water
•
are made of aluminium.
On account of the danger of spot corrosion the
•
chloride, nitrate and sulfate contents of the heat-
ing water must not exceed 200 mg/l in total.
The pH value of the heating water should lie be-
•
tween 8,0 and 8,5 after 6 - 12 weeks of heating
operation.
Filling and replacement water
4.3
For a plant using Hoval boilers untreated drinking
•
water is generally best suited as fil ling and replace-
ment water. However, the quality of the untreated
drinking water must at least fulfil the standard set
in VDI 2035 or be desalinated and/or be treat ed
with inhibitors. The stipulations of EN 14868 must
be observed.
In order to maintain a high level of boiler ef ficiency
•
and to avoid overheating of the heati ng surfaces
the values given in the
table 1
should not be ex-
ceeded (dependent on boil er performance ratings
- for multi-boiler plants rating of smallest boiler ap-
plies - and on the water content of the plant).
The total amount of filling and replacement water
•
which is used throughout the total ser vice life of
the boiler must not exceed three times the water
capacity of the plant.
Boilers with aluminum: generally inhibitors may be
•
filled in only by a specialized company.
If a reduction in water hardness is necessary we
•
recommend a complete desalination (softening is
not appropriate). Residual tap water might remain
in the plant as a result of the preceding flushing
process, entailing an increase in the sum of alka-
line-earths to approx. 0,5 mol/m
3
. During the fill-
ing procedure the conductance of the filling water
should be supervised. This should be to approx.
100 µS/cm .
After filling the conductance of the plant water
•
should be between 50 and 200 µS/cm. The pH val-
ue will adjust itself thereby from
initially 6,5 - 7,5 after some
weeks been in use on 8,0 - 8,5.
If this should not be the case,
then specialized company for
the water treatment is to be
assigned. This compa ny must
as soon as the adjustment of
the cor rect pH value has been
completed by inhibitors, which
are suitable for aluminium ma-
terials also regularly check the
inhibitor concentration and the
pH value.
Table 1
Maximum filling capacity based on VDI 2035
Available for boiler with < 0,3l/kW water capacity
Total hardness of the filling 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 filling quantity without desalination
30 to 50 kW
NO DEMAND
50 l/kW 50 l/kW 20 l/kW 20 l/kW 20 l/kW
50 to 200 kW
50 l/kW 20 l/kW 20 l/kW
always desalinate
1
total of alkaline earths
2
If the conductance in µS/cm exceeds the tabular value an analysis of the water is necessary.
