VESTEL WATER HEATER SERVICE MANUAL
VESTEL BEYAZ EŞYA A.Ş. (Air Conditioning Quality Assurance Department)
Page
16
5-9
ANODE STICK
Corrosion is a chemical process that occurs between water heater metal (tank, pipes, heating coils) and water
surrounding it. Corrosion causes punctures in the tank, reduces mechanical resistance of elements and damages
heating element. Reasons that cause corrosion are as follows:
1. Oxygen solution (example: from 5 mg/l at high temperature and up to a maximum of 12 mg/l at low temperature)
2. Salts that harden water.
Magnesium anode is used to prevent tank from punctures.
Corrosion develops in three phases:
1. Water soluble oxygen comes into contact with the inner surface of the drum.
2. Drum iron starts to dissolve (atom loses two electrons and become Fe ++ ion).
3. Iron ion is separated from drum surface and turns into rust by combining with oxygen (FeO). In this case, formation
of punctures start within the tank.
4. Grounding connections must certainly be provided during product installation as floating power connections
prevent chemical reactions between anode and drum and cause corrosion and punctures in the drum.
Both iron and magnesium are water soluble; magnesium is more electropositive compared to iron (become mg ++
more easily). Thus, it is the magnesium that becomes a solution.
At this point, magnesium leaves anode and combines with oxygen atoms. Corrosion ends, in other words, while
thermostat stays the same magnesium anode is abraded.
Water received
from the main
Pressure rises as water is heated. Water is
transferred to drain hose when pressure
exceeds 8 bar.
