ACV E-tech P 115, Installation Operation & Maintenance

Page: 8 / 40

8
RECOMMENDATIONS FOR THE PREVENTION OF CORROSION AND SCALING IN
HEATING SYSTEMS
RECOMMENDATIONS FOR THE PREVENTION OF CORROSION AND SCALING IN HEATING
SYSTEMS
How oxygen and carbonates can aff ect the
heating system
Oxygen and dissolved gasses in the water of the prima-
ry circuit contribute to the oxidation and the corrosion of
the system components that are made of ordinary steel
(radiators, ...). The resulting sludge is then deposited in
the appliance exchanger.
The combination of carbonates and carbon dioxide in
the water results in the formation of scale on the hot
surfaces of the installation, including those of the appli-
ance exchanger.
These deposits in the heat exchanger reduce the wa-
ter fl ow rate and thermally insulate the exchange sur-
faces, which is likely to damage them.
Sources of oxygen and carbonates in the heat-
ing circuit
The primary circuit is a closed circuit; the water it con-
tains is therefore isolated from the mains water. When
maintaining the system or fi lling up the circuit, water re-
newal results in the addition of oxygen and carbonates
in the primary circuit. The larger the water volume in
the system, the larger the addition.
Hydraulic components without an oxygen barrier (PE
pipes and connections) admit oxygen into the system.
Prevention Principles
1. Clean the existing system before installing a new
appliance
Before the system is fi lled, it must be cleaned in accord-
ance with standard EN14336. Chemical cleaning agents
can be used.
If the circuit is in bad condition, or the cleaning operation
was not effi cient, or the volume of water in the installation
is substantial (e.g. cascade system), it is recommended
to separate the appliance from the heating circuit using
a plate-to-plate exchanger or equivalent. In that case, it
is recommended to install a hydrocyclone or magnetic
fi lter on the installation side.
2. Limit the fi ll frequency
Limit fi ll operations. In order to check the quantity of wa-
ter that has been added into the system, a water meter
can be installed on the fi lling line of the primary circuit.
Automatic fi lling systems are not recommended unless
the fi ll frequency is monitored and the scale and corro-
sion inhibitor remain at the correct levels.
If your installation requires frequent water refi lling, make
sure your system is free of water leaks.
Inhibitors may be used in accordance with standard
EN 14868.
3. Limit the presence of oxygen and sludge in the
water
A deaerator (on the appliance fl ow line) combined
with a dirt separator (upstream of the appliance) must
be installed according to the manufacturer's instruc-
tions.
ACV recommends using additives that keep the ox-
ygen in solution in the water, such as Fernox (www.
fernox.com) and Sentinel (www.sentinel-solutions.net)
products.
The additives must be used in accordance with the
instructions issued by the manufacturer of the water
treatment product.
4. Limit the carbonate concentration in the water
The fi ll water must be softened if its hardness is high-
er than 20° fH (11,2° dH).
Check regularly the water hardness and enter the val-
ues in the service log.
Water hardness table :
5. Control the water parameters
In addition to the oxygen and the water hardness, oth-
er parameters of the water must be checked.
Treat the water if the measured values are outside the
range.
Water hardness °fH °dH mmolCa(HCO3)2 / l
Very soft 0 - 7 0 - 3.9 0 - 0.7
Soft 7 - 15 3.9 - 8.4 0.7 - 1.5
Fairly hard 15 - 25 8.4 - 14 1.5 - 2.5
Hard 25 - 42 14 - 23.5 2.5 - 4.2
Very hard > 42 > 23.5 > 4.2
Acidity 6,6 < pH < 8,5
Conductivity < 400 μS/cm (at 25°C)
Chlorides < 125 mg/l
Iron < 0,5 mg/l
Copper < 0,1 mg/l
EN
Technical Specifications