17
Subject to technical amendments without notice | 83050700gUK – Translation of the original operating manual | ait-deutschland GmbH
Part 2 of VDI 2035 also points out the reduction in total
salt content (conductivity). The risk of corrosion is far
lower if deionised water is used than is the case if the
system is operated with salty, i.e. softened water.
Even if the water has been softened beforehand, it
contains dissolved, corrosion-promoting salts, which
act as electrolytes due to the use of different materials
in the heating system and therefore accelerate
corrosion processes. This can ultimately result in
pitting.
On the safe side with low-salt operation
The problems listed above do not occur at all with
low-salt operation, as neither corrosive salts such as
sulphates, chlorides and nitrates nor alkalising sodium
hydrogen carbonate are in the heating water. The
corrosive properties of deionised water are very low
and in addition, fur cannot form in the boiler. This is the
ideal approach for closed heating circuits, in particular,
because low oxygen input into the heating circuit can
also be tolerated.
In general, when the system is filled with deionised
water, the pH value sets itself within the ideal range
due to „self-alkalinisation“. If necessary, a pH value of
8.2 can be very easily alkalised by adding chemicals.
In this way, optimum protection of the entire heating
system is achieved.
Monitoring
Analytical recording and monitoring of the relevant
water values and the added active conditioning
substances is of decisive importance. Therefore, they
should be monitored regularly using appropriate water
test equipment.
23.2
Flush and fill the heating circuit
and
the domestic hot water tank
Place a bleeder (vent) at the highest point of the
heating circuit in the heating water outlet (flow).
If necessary, place a bleeder at the highest point
of the heating circuit in the heating water inlet
(return).
Open unit, if closed.
“Transport to the installation location”, and
Flush and fill the unit via the filling and draining tap.
IMPORTANT
Do not exceed a pressure of 2.5 bar when
flushing the unit. The drain line of the heat
-
ing circuit safety valve must be closed before
flushing and filling.
24 Bleeding
View of inside of unit
1 Electrical switchbox
2 Overflow valve
3 Electric heating element
4 Circulation pump, heating circuit
5 Fill and drain tap, heating circuit
