Viessmann VITOBLOC 200 - Heating water

Appendix
VITOBLOC 200 EM-530/660 version SCR Installation instructions 33
5841436 GB
10.4 Heating water
Quality regulations for heating water as per VDI
Guideline 2035
The quality of the heating water is defined by the
manufacturer's instructions and VDI Guideline 2035
"Guidelines for the prevention of damage due to corrosion
and scaling in DHW and hot water heating systems" in
their respectively applicable version.
The chloride content should not exceed 30 mg/l. In
addition to this requirement, the heating water quality
must meet the requirements of VDI 2035.
VDI 2035 lays down requirements regarding the heating
water quality subject to the total heating output and the
specific system capacity.
PLEASE NOTE
► In the case of multiple heat
generators, the specific system
volume is determined by means
of the lowest individual heating
output. For more details, see
VDI 2035.
Total heating output
Total hardness
Total hardness
Total hardness
in kW
in °dH
at < 20 l/kW
smallest boiler heating
surface
in °dH
at > 20 l/kW < 50 l/kW
smallest boiler heating
surface
in °dH
at > 50 l/kW
smallest boiler heating
surface
< 50 kW
No requirement or
< 16.8 °dH
11.2 °dH
0.11 °dH
> 50 kW < 200 kW
11.2 °dH
8.4 °dH
0.11 °dH
> 200 kW < 600 kW
8.4 °dH
0.11 °dH
0.11 °dH
> 600 kW
0.11 °dH
0.11 °dH
0.11 °dH
Tab. 5 Quality values of the fill and top-up water for heating systems with Vitobloc 200 CHP units
PLEASE NOTE
► The on-site dirt separator should
be cleaned every six months.
Corrosion prevention
Corrosion in heating systems is essentially caused
by the presence of oxygen in the heating water.
Therefore, the likelihood of corrosion damage on
metal materials is low when the heating water has
a low oxygen content.
Possible sources of oxygen ingress are:
● Build-up of negative pressure in the heating
system
● Air pockets in the fill and top-up water
● Oxygen ingress via direct contact of heating water
with air (open vented system)
● Oxygen diffusion via permeable components such
as seals, plastic pipes, membranes and hoses
● Oxygen content of the fill and top-up water
● Inadequately sized expansion vessel
Chemical additives in the heating water
As a rule, no corrosion forms in correctly designed,
installed and operated sealed unvented hot water
heating systems. There is therefore generally no
need for chemical additives.
PLEASE NOTE
► Do not add any chemical additives
to the heating water without
confirmation from the manufacturer
that the chemicals are harmless
with regard to the design of the
heating system and the materials
used.