Anti-corrosion cathodic system of two magnesium anodes, protecting the entire reservoir from corrosion.
This is possible thanks to not one, but two magnesium anodes with increased mass that we put in our devices. The first anode is mounted on the flange, and the second is located at the top of the water tank, which is the hottest and most endangered area in a water heater.
Cathodic protection is used for additional prevention against corrosion processes in the water reservoir. No matter how perfect the glass-ceramic coating (enamel) is, there is always a risk of micro-pores appearing, as well as defects at the places of the welds where water has access to the base metal.
The cause of corrosion lies in the difference between the electrode potentials of the metal (in the specific case - the black steel of the water reservoir) and its environment ((copper electric heater, stainless pipe, brass couplings, etc.). Corrosion is an electrochemical process in which destroys the surface of the metal.As a result, cracks appear in the water container, which lead to the flow of the water heater.
As given, corrosion protection is an active method of protection and directly attacks the cause of the problem. The method is based on the interdependence between the potential and the rate of corrosion development. Very weak currents flow between the anodes and the defective surface - measured in µS /microsiemens/ - the opposite of corrosion currents. Because anode protectors also create potential. Very weak currents flow between them and the defective surface, opposite to the corrosion currents. Thus, cathodic protection slows down and, under certain conditions, prevents corrosion.
The electrical conductivity of water is also very important for the effective operation of cathodic protection. At values above 200 µS, such as hard water, the protection works perfectly. In soft waters with electrical conductivity below 100 µS, the effect of cathodic protection performance is significantly reduced.
The material from which the anodes are made is essential. In contrast to the widely distributed cheap aluminum alloy anodes, in ELDOM water heaters we use special magnesium protectors.
For water heaters with a volume of 50 to 750 liters and for water heaters with heat exchangers, where the coil is a kind of screen, after repeated tests we have reached the effective solution of using protection with 2 anodes. We have equipped all coil water heaters with a capacity of 50 to 750 liters with 2 anode protectors.
In the process of cathodic protection, part of the mass of the magnesium anode is lost - it gradually melts. That's why specialists call it a "sacrificial anode". When we install protective anodes and customers pay for it, there needs to be a way to evaluate or measure their performance. Only ELDOM water heaters provide this possibility due to the isolated installation of the anode, as well as the strong galvanic connection to the housing by means of a cable, and not by direct contact. The performance of cathodic protection can be evaluated by a service technician.
There is another, much more convenient solution, using an anode tester built into the water heater. This is a simple and inexpensive milliammeter that, at the push of a button, displays the condition of the anode protectors. If the indicator is in the green zone, it means that anti-corrosion currents are flowing. The red area showing means you need to call your service technician. Anode replacement manipulation is quick and cheap. This way you increase the life of your water heater by at least another 3 years.
It is interesting that with most brands of water heaters there is no possibility of checking with an anode tester. Therefore, their users, even if they want to, cannot control the operation of cathodic protection.
Security - we have ensured the reliability of ELDOM devices with the following protections:
• The specially designed and patented ELDOMINVEST elliptical flange provides fail-safe protection against excessive pressure. It is designed so that, in the event of failure of all other protections, it releases the pressure in the water tank and the water flows into the bath without causing explosions and damage.
The water heater is a device that operates under pressure of the order of 6-8 atmospheres. ELDOMINVEST manufactures all its water heaters with reliable 6-level protection. The eventual failure of the first 5 defenses is extremely rare and unlikely, but if it does, it remains the last, purely mechanical defense. This is the elliptical flange located at the bottom of the water tank. It is the specially designed weakened part of the ELDOM water heater. Its purpose is to protect against a possible explosion caused by dangerously high pressure. Without protection, the water in the water container exceeds 100⁰C, and the pressure in the device rises sharply to dangerous values - 16-17 MPa. At this pressure, the flange hole at the bottom of the reservoir begins to deform. This change in shape from elliptical to spherical causes the flange clamp to release. Thus, steam and water flow freely from the reservoir without causing explosions and damage.
• Combined metal valve with two protection functions. It simultaneously protects both from the return of hot water into the plumbing installation in case of a drop in pressure, and from increased pressure in the device above the nominal value.
• Frost protection . The thermostat automatically maintains the water temperature in the water heater above 5 ° C.
• Precision capillary thermal switch - instantly interrupts the electrical circuit in the presence of a defect.
