Water quality
Water quality requirements
Note
Observing the following requirements is
necessary to safeguard your warranty
rights.
Prevention of damage due to scaling
Prevent excessive scale build-up (cal-
cium carbonate) on the heating surfaces.
For heating systems with operating tem-
peratures up to 100 °C, directive
VDI 2035 sheet 1 "Prevention of damage
in water heating installations - Scale for-
mation in domestic hot water supply
installations and water heating installa-
tions" applies [in Germany], with the fol-
lowing standard values (see also the full
explanations in the original directive).
Total heating output
kW
> 50 to ≤ 200
> 200 to ≤ 600
> 600
The standard values assume the follow-
ing:
■ 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 output of the
smallest boiler.
■ All measures to prevent corrosion on
the water side in accordance with
directive VDI 2035 sheet 2 have been
implemented.
22
The warranty excludes damage due to
corrosion and scaling.
Total alkaline earths
mol/m
3
≤ 2.0
≤ 1.5
< 0.02
Soften the fill and top-up water in heating
systems operating under the following
conditions:
■ The total of alkaline earths in the fill
and top-up water exceeds the stand-
ard 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 output of the
smallest boiler.
Total hardness
°dH
≤ 11.2
≤ 8.4
< 0.11