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83051400aUK © Alpha-InnoTec GmbH
ommendations and installation instructions of the heat
pump manufacturer.
Part 2 of VDI 2035 also points out the reduction in to-
tal 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 con-
tains dissolved, corrosion-promoting salts, which act as
electrolytes due to the use of different materials in the
heating system and therefore accelerate corrosion pro-
cesses. This can ultimately result in pitting.
Contamination and deposits in the heating circuit can
cause malfunctions
rinse,FillandbleedtheheatingCirCuitand
hotwaterbuFFertank
To bleed the hot water tank, the heating circuit and hot
water circuit must be rinsed simultaneously.
onthesaFesidewithlow-saltoperation
The problems listed above do not occur at all with low-
salt operation, as neither corrosive salts such as sul-
phates, chlorides and nitrates nor alkalising sodium hy-
drogen carbonate are in the heating water. The corro-
sive properties of deionised water are very low and in
addition, fur cannot form in the boiler. This is the ide-
al approach for closed heating circuits, in particular, be-
cause low oxygen input into the heating circuit can also
be tolerated.
In general, when the system is lled with deionised wa-
ter, 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.
Fill and bleed the heating circuit...
In addition, open the bleeding valve on the condens-
er of the heat pump. Bleed condenser.
damagethatCanoCCurinCaseoFnon-
ComplianCe
- Malfunctions and the failure of components (e.g. pumps,
valves)
- Internal and external leaks (e.g. from heat exchangers)
- Cross-section reduction and blockaging of components
(e.g. heat exchanger, pipes, pumps)
- Material fatigue
- Gas bubbles and gas cushion formation (cavitation)
- Negative effect on heat transfer (formation of coatings,
deposits) and associated noises (e.g. boiling noises, ow
noises)
limesCale–theenergykiller
Filling with untreated drinking water inevitably leads
to the precipitation of all calcium as scale. The conse-
quence: limescale deposits form on the heat transfer
surfaces of the heating. The efciency falls and the en-
ergy costs rise. A rule of thumb is that 1 millimetre of
limescale deposit causes an energy loss of 10%. In ex-
treme cases it can even cause damage to the heat ex-
changers.
watersoFteningtoVdi2035–parti
If the water is softened before the heating is lled, in
accordance with the VDI 2035 guidelines, no scale can
form. This effectively and permanently prevents lime-
scale deposits and the resulting negative effects on the
entire heating system.
Corrosion–anunderestimatedproblem
VDI 2035, Part II, deals with the problem of corrosion.
Softening the heating water can prove to be insufcient.
The pH value can signicantly exceed the limit of 10. pH
values higher than 11 can set in, which even damage rub-
ber seals. The VDI 2035, Part 1 guidelines are fullled,
however, VDI 2035, Part 2 suggests a pH value between
8.2 and maximum 10.
If aluminium materials are used, which is the case in
many modern heating systems, a pH value of 8.5 must
not be exceeded, because otherwise there is a threat
of corrosion – and aluminium is attacked without the
presence of oxygen. Therefore, apart from softening the
heating ll and additional water, the heating water should
also be appropriately conditioned. This is the only way
to comply with the VDI 2035 requirements and the rec-