Viessmann VITOCROSSAL 300, Service Instructions Manual

Page: 30 / 36

Prevention of damage due to scaling
Excessive scale deposits (calcium carbonate) on the heating surfaces should
be prevented. For heating systems with operating temperatures up to 100 °C,
the VDI Directive 2035 sheet 1 "Prevention of heating system damage
–
scaling
in DHW and hot water heating systems" applies [in Germany] together with the
following standard values (see also the full explanations in the original Direc-
tive).
Total output
kW Total of alkaline earths
mol/m
3
Total hardness
°dH
> 50 to
≤
200
≤
2.0
≤
11.2
> 200 to
≤
600
≤
1.5
≤
8.4
> 600 < 0.02 < 0.11
The standard values assume the fol-
lowing:
& The volume of fill and top-up water
will not exceed three times the
water content of the heating system
during its service life.
& The specific system volume is less
than 20 l/kW output. In multi-boiler
systems, apply the output of the
smallest boiler.
&
All measures to prevent corrosion
on the water side in accordance
with VDI 2035 Sheet 2 have been
implemented.
Soften the fill & top-up water in heat-
ing systems operating under the fol-
lowing conditions:
&
The total of alkaline earths in the fill
& top-up water exceed the standard
value.
&
Higher fill & top-up water volumes
are expected.
&
The specific system volume is less
than 20 l/kW output. In multi-boiler
systems, apply the output of the
smallest boiler.
& In systems > 50 kW, install a water
meter to record the volume of the fill
& top-up water. Enter the volume of
water and the water hardness into
the boiler service checklists.
&
For systems with a specific system
volume in excess of 20 l/kW output
(apply the output of the smallest
boiler in multi-boiler systems), apply
the requirements of the next higher
category of total output (in accor-
dance with the table). In case of
severe excess (> 50 l/kW), soften
the water down to a total of alkaline
earths
≤
0.02 mol/m
3
.
Water quality requirements
(cont.)
30
Specification
56
92
405
GB