Owners of storage or flow-through water heating units are constantly faced with the problem of scale deposits on the walls and bottom of the tank. To combat it, manufacturers offer various drugs, including special chemical solutions. In addition, folk ingenuity allows the use of various auxiliary means (citric acid, for example) for this. One of the most effective methods to get rid of scale in heating equipment is to install a protective anode for the boiler.
Why do you need an anode
To understand why a magnesium anode in water heaters is needed, you need to consider the very principle of salt deposition (scale formation). The water entering the tank always contains more or less natural (soluble) salts. When heated, they react with the metal of the coating of the coil of the electric heater and parts of the storage tank of the boiler.
The material of the tank, made of corrosion-resistant stainless steel, under the influence of hard water changes its structure over time and gradually deteriorates.
On the other hand, there are metals, the chemical activity of which is so great that they "divert" a significant portion of the reagents to themselves - they include the magnesium necessary for this. The main purpose of an anode based on it is to protect stainless metal surfaces from salt deposits formed as a result of contact with water.
Since limescale deposits and most types of metals have different coefficients of expansion, the heating element deforms over time. The scale formed on it reduces the heat transfer, and the heating of the water slows down. As a result, the indicator of the useful power supplied to the load drops sharply. When installing an anode in a water heater, it is possible to get rid of all of the above disadvantages and significantly reduce the rate of electricity consumption.
Features of models from different manufacturers
The well-known Slovenian company Gorenje conducted an experiment, during which a modern anode was installed on old models of water heaters, for which magnesium was used. These experiments gave positive results, which was reflected in the increase in the efficiency of the devices by reducing the time for heating the water when the tank is completely filled.
Another popular company, Atlantic, has also tested its own models. As a result, an amazing result was obtained, which showed a double increase in the service life of the equipment.
Thermex company, which produces modern water heaters, is known for the fact that its products are distinguished by long service life due to the presence of glass-ceramic coating on the heating elements.
The first company to install a magnesium element in its products is Ariston, which is distinguished by high quality indicators of the manufactured equipment.
Types of anodes and principle of operation
In accordance with the material used in the manufacture, anodes for boilers are divided into the following types:
- magnesium;
- titanium.
The titanium element, like magnesium, is also located to the left of the periodic table - it is able to attract cations to itself.
Principle of operation
The basic principle of using a magnesium anode is the increased chemical activity of this metal, which is significantly higher than the same indicator for steel parts. Due to this, the water around them is saturated with magnesium cations, which bind the oxygen formed when heated by the heating element. Due to this reaction, the boiler elements are protected from corrosion.
An overabundance of cations leads to the formation of loosened scale due to the binding with carbon anions, which are subsequently easily removed from the structure. The part formed in the form of an insoluble precipitate settles over time on the anode itself.
The elements of the boiler fail, since over time the consumption of the magnesium anode is observed, which gradually wears out due to corrosion. With intensive use of a home boiler, taking into account the poor quality of tap water, you should be prepared for an early replacement of an element that has served its life.
Replacing the magnesium anode
The magnesium anode looks like an ordinary metal rod with an alloy applied to it, approximately 15 millimeters thick. At the end there is a threaded rod made of metal. The average length of the pin is approximately 140-660 mm, and the studs are approximately 14 to 25 mm.
The technical serviceability or malfunction of the magnesium anode is easily monitored visually. When examining it, it should be borne in mind that severe wear and tear will significantly affect the performance of all heating equipment. For all manufacturers of these elements, their design is different, and sometimes it is quite different. This fact forces many consumers to purchase for replacement a type of anode, which is specially designed for this model of a water heater.
With long-term operation of the equipment (more than 15 months), it is recommended to proceed in the following order:
- Disassemble the unit to a state that will allow you to gain free access to the surveyed area. To do this, unscrew the screws securing the device cover with a magnetic screwdriver, remove it or move it aside.
- When the length of the wires is sufficient, you need to pull the thermostat and sensor out of the tube (it is fixed on the contacts). Otherwise, you will have to disconnect the power cable and only then remove the thermocouple.
- Using a wrench, you need to unscrew the flange of the block, and then remove the heating element together with the anode.
- Using the pliers, you should grab the worn-out element or the remainder in the form of a thin rod and unscrew it from the socket.
- If traces of severe damage are found, this part will have to be completely removed and replaced with a new product.
The boiler kit contains a special tool (hairpin) by means of which the anode is unscrewed from the threaded hole of the heating element flange.
When dismantling, it is important to pay attention to the fact that the standard size and the total number of fastening bolts depends on the specific modification of the boiler. On Ariston, for example, there are fasteners that have five working nuts for a 10 mm wrench, or one metal spacer bar fixed on one nut by 14 mm.
Wear criteria
There are several easily identifiable indicators that the time has come to completely clean the unit and then change the magnesium anode:
- when the household device is turned on, after a while, the protection is triggered, which is explained by the presence of a thick layer of scale on its heating element;
- the previously observed water heating is completely absent when the boiler is operating normally;
- the equipment case begins to periodically "beat" with current, which is a sign of a violation of the quality of insulation due to the destruction of individual parts.
One of these manifestations is a reason to immediately stop operating the boiler and start examining it.Only a thorough study of the state of the electric water heater and the anode allows us to make a final conclusion about the need to replace them.
Specialist advice
The average life of a typical magnesium cell is two years. However, in special cases, this figure can take on other values - 1 year or 3, most often it depends on the quality of the water. This applies only to models of water heaters equipped with steel bulbs.
Boilers equipped with a stainless steel inner flask are also presented on the domestic market. Taking into account all these points, experts recommend paying attention to the following details:
- As often as possible, check the operation of the boiler unit by ear.
- If you hear hiss during heating, the contact at the attachment point of the heating element has deteriorated, covered with an insulating film.
- After some time, it is advisable to look into the inner space of the boiler. Having discovered 50% destruction of the anode, you need to look for a replacement for it.
- You should try to clean the boiler a little more often than indicated in the operating instructions for the product.
It is not allowed to start up the heating unit without an anode.
