Viessmann VITOPLEX 300 Service Instructions Manual page 18

Water quality
Water quality requirements
Heating systems with rated operating temperatures up to 100 °C (VDI 2035)
The water used in heating systems must comply with
the chemical values of the Drinking Water Ordinance
[Germany]. If well water or similar is used, check its
suitability before filling the system.
Avoid excessive scale deposits (calcium carbonate) on
the heating surfaces. For heating systems with operat-
ing temperatures up to 100 °C, Guideline VDI 2035
Part 1 "Prevention of damage in water heating installa-
tions - Scaling in domestic hot water supply installa-
tions and water heating installations" applies together
with the following standard values. For more informa-
tion, see the explanations for guideline VDI 2035.
Total heating out-
>
put in kW
≤
Total alkaline
3
earths in mol/m
Total hardness in
≤
°dH
The standard values assume the following conditions:
■ The total 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
■
heating output. In multi boiler systems, apply the out-
put of the smallest boiler.
■ All measures to prevent corrosion on the water side
in accordance with VDI 2035 Part 2 have been
implemented.
Soften the fill and top-up water in heating systems with
the following conditions:
■ The total of alkaline earths in the fill and top-up water
exceeds the standard value.
■ Higher fill and top-up water volumes are expected.
The specific system volume is greater than 20 l/kW
■
heating output. In multi boiler systems, apply the out-
put of the smallest boiler.
When designing the system, observe the following:
■ Install shut-off valves in each section. This prevents
the need for draining all the heating water in the case
of repairs or system expansion.
Install a water meter to record the volume of fill and
■
top-up water. The volumes and hardness of the top-
ped-up water volumes must be entered in the boiler
service instructions.
■ For systems with a specific volume greater than
20 litres/kW heating output (for multi boiler systems,
the output of the smallest boiler should be used), the
requirements of the next highest total heating output
group should be applied (using the table). If even
bigger ( 50 litres/kW), soften the water down to a
>
total of alkaline earths of
18
50 to 200 to
> >
200 600
≤
2.0 1.5 < 0.02
≤ ≤
11.2 8.4 < 0.11
≤
0.02 mol/m 3 .
≤
Operating information:
Start the system gradually at a high heating water
■
flow rate, starting with the lowest boiler output. This
prevents localised concentration of limescale depos-
its on the heating surfaces.
■ For multi boiler systems, all boilers should be started
at the same time to prevent the entire volume of
limescale settling on the heat transfer surface of only
one boiler.
■ During expansion or repair work, only drain the nec-
essary sections.
■ Where water treatment is required, treat even the
first fill of the heating system prior to commissioning.
This also applies to any subsequent filling, e.g. when
600
adding top-up water or after a repair, or for any sys-
tem expansion.
■ Periodically inspect, clean and activate all filters, dirt
traps or other blow-down or separating facilities in
the heating water circuit after reinstalling or installing
for the first time. Thereafter, this may be one as
required, depending on the type of water treatment
applied (e.g. water softening).
The build-up of limescale deposits on the heating sur-
faces will be minimised if these instructions are fol-
lowed.
If failure to observe guideline VDI 2035 results in
harmful limescale deposits, the service life of the
installed boilers will in most cases have already been
reduced. Removing limescale deposits may be an
option to restore the operating capability. This must be
carried out by Viessmann Industrieservice or a special-
ist contractor. Inspect the heating system for possible
damage prior to returning it into use. The faulty operat-
ing parameters must be corrected in order to prevent
excessive scale build-up from reoccurring.