Magnesium anode. Magnesium anode for water heaters: what is it used for and how important is this element. Is it necessary to install a magnesium anode in a water heater?

Many owners of a cylinder water heater are aware that the internal tank of the boiler needs to be systematically cleaned of rust and scale. During preventative work The magnesium anode also requires replacement, which should be done at least once every two years. But what is a magnesium anode for?, what functions it performs – we will consider in this article.

Why do you still need a magnesium anode in a water heater? Most often, the internal tanks of water heaters are made of steel, which is an alloy of iron and carbon. It is this factor that has the main influence on the durability of the boiler. When oxygen present in water interacts with the steel walls of the container, iron oxides or simply rust are formed.

It is worth noting that without protection inner surface tanks in the form of a layer of enamel, glass porcelain or glass ceramics, the boilers will not last even a third of the declared service life.

But still, during operation, the protective layer is subject to regular temperature changes, which lead to the formation of microcracks. And then the metal of the tank is defenseless against the oxidizing environment.

Many will remember some models of boilers, the tank of which is made of stainless steel. However, this is also not a guarantee of long-term performance. But the point is all in the requirements for devices of this type - the container of the products must be made of food-grade stainless steel, but, unfortunately, it does not have sufficient stability. During operation, they also corrode, but this takes a little more time.

The problem with stainless steel tanks comes from another direction - welding is used for their manufacture. In fact, welded seams shorten the service life of such tanks. The fact is that when heated during welding, all the additives that provide it with anti-corrosion qualities burn out from the alloy. Leakage of such boilers at the seams is one of the main types of failures.

It is for the purpose of additional protection of the surface of the container from the negative effects of water that manufacturers install a magnesium anode in the tank. It is made in the form of a steel rod, which is coated with a significant layer of magnesium alloy. The anode is attached inside the tank using a threaded part, and is most often placed near the heating element.

The essence of water heater protection

The purpose of installing a magnesium anode in a water heater is now clear. And to understand how metal is protected from corrosion, it is enough to remember school lessons chemistry.

The iron from which the internal tank is made interacts with oxygen present in the water during operation. As a result, iron oxide is formed. Thus, iron, exposed to oxidative processes, is an anode.

Manufacturers, when installing a magnesium part in a tank, pursue two goals:

Magnesium gives up electrons from its atoms much more easily than iron. One could even say that iron simply does not have time to interact with oxygen. Thus, magnesium acts as a sacrificial anode that dissolves to protect other metal components from corrosion. Since, in chemical reactions In the boiler tank, magnesium reacts instead of iron, then the inner surface of the container remains untouched.
Tap water contains not only oxygen, but also dissolved calcium salt. It settles in the form of scale on the internal parts of the water heater. When interacting with the hot surface of the heating element, scale turns into real calcium stone, reducing the heater, as a result, the heating element fails. The use of a magnesium anode helps solve this problem as well - its electrons, by displacing calcium ions, transform scale from solid salt into a loose substance that can be easily removed from the internal parts of the boiler.

However, during its operation, the protective anode is quickly destroyed, as a result of which its periodic replacement is required.

Otherwise, the service life of the device will depend only on the quality of the internal coating, as well as the material of the tank walls, temperature regime and water composition.

The magnesium anode must be replaced at 60% wear. Most often this happens every 1.5 years of operation.

It is after this period that the rod becomes very loose and begins to crumble easily. The element is replaced with a rod with similar geometric parameters. At the same time, it is necessary to remove scale from the inner surface of the container and heating element each time. This will significantly extend its service life and also improve the quality of hot water.

Video instructions for replacing the anode and cleaning the water heater

A special feature of the storage boiler is its high susceptibility to corrosion. Interacting with water during an oxidative reaction, the metal tank begins to corrode over time. But this device is equipped with an element that is exposed to water instead of iron - this is a magnesium anode for a water heater.

What is a magnesium anode?

The anode device is a threaded rod made of non-ferrous metal. It is coated with a thick layer of magnesium, which is subsequently exposed to water.

Magnesium rods are different:

diameter
length (the longer the anode element, the longer it will last)
threaded (there are models without threads, they are inserted inside the hole).

There are a number of anode elements that make up the range of standard universal modifications. They are suitable for many water heating devices.

As a rule, the service life of a magnesium rod is 1-2 years. Budget options have a period of active activity of no more than a year. Models of a higher class are more than two years old.

Modern water heating boilers are not equipped with any warning system about the anode element running out of its life. To see its condition, you need to disassemble the equipment, appearance determine the degree of wear. If approximately 30% of the original coating remains, a quick replacement is expected.

Why is a magnesium anode needed in a water heater?

In the water heater magnesium rod performs a protective function:

Protects the internal coating of the storage tank from premature cracking, corrosion, and failure. Boiler tank made of steel. The iron alloy and oxygen, which is actively released during water heating, interact. An oxidation reaction occurs, iron oxide (rust) is released, and the steel corrodes.
For protection, manufacturers cover the inner surface of the tank with glass ceramics and enamel. Over time, due to frequent temperature changes, this protection becomes covered with cracks, through which the liquid gains access to the metal.
Stainless steel (food grade) containers are also subject to corrosion, but this process is longer lasting. Stainless steel tanks corrode and then leak (often happens) along the weld.

Instead of heating element exposed to water during an oxidative reaction. Placed near the electric heater (screwed into the hole or inserted). Being nearby, it absorbs the effects of liquid, softens hardness, and prevents rust from hardening. Thanks to this, instead of plaque, rusty flakes form inside the boiler.

The above points are the answer to the question why an anode element is needed.

Operating principle

As the water heats up, the amount of oxygen increases. It interacts during an electrochemical reaction with heavy metals (electric heating element, tank capacity), as a result, rust is formed. The protective rod is coated with magnesium because it reacts with oxygen faster than iron. Anodic magnesium binds oxygen molecules, this is cathodic protection of the metal.

Water contains dissolved calcium salts. When deposited on the hot heating element, they harden, becoming limestone. The thermal conductivity of the heating element decreases, normal operation stops, and the element may burn out.

The use of an anode element works in this way: magnesium electrons replace calcium ions. Therefore, the scale does not harden, but forms in flakes and becomes loose, making it easier to remove.

An aggressive environment destroys the anode device. It must be changed after a year of use. Let's look at how to replace a magnesium anode below.

Replacing the magnesium anode in a water heater

How to replace a magnesium anode? The process looks like this:

Disconnect the heating tank from the power supply.
Stop feeding cold water.
Drain off all liquid.
Remove the tank from the wall (a larger tank can be serviced permanently).
Open the storage tank according to the instructions.
Get the flange with the heating element and anode.
Visually assess the degree of wear of the element and its performance.
When replacing, unscrew the old rod and install a new one.
Rinse the container, the heating element, and remove the scale.
Assemble the water heating equipment and install it in its original place.

It is necessary to carefully monitor the operation of the boiler. If extraneous noise occurs, inspect the condition of the anode device and heating element.
Constantly check its condition.
Do not use water heating equipment without a safety rod installed inside.
You can replace the used part yourself; calling a technician is not necessary.
Salts will always form inside the container. It is recommended to descale the internal cavity at least once a year.

The versatility of some rod options allows you to install a magnesium anode for an Ariston, Electrolux, and other popular brands of water heater. They are also suitable for a Russian-made Thermex water heater. The price range depends on the dimensions of the anode rod and the manufacturer's brand.

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Now you will find out why you need a magnesium and titanium anode in a water heater (boiler). We will also consider how to replace the anode with your own hands.

It often happens that the time comes for owners of water heaters to clean the tank from scale and corrosion and need to replace the anode. But what an anode is, man does not know. From the article you will learn what it is and in general why it is needed in a water heater.

You can find out the price and buy heating equipment and related products from us. Write, call and come to one of the stores in your city. Delivery throughout the Russian Federation and CIS countries.

Water heater anode

First, let's understand that the anode is a boiler element in the form of a thick metal rod (magnesium or titanium).

The main material used for the production of internal tanks is stainless steel (an alloy of iron and carbon). Heated oxygen, being in the water, begins to be released and interacts with the capacity of the steel tank. After this, the formation of oxide begins.

In order to protect the internal surface of the water heating structure, protective enamel is used. It makes the service life longer and at the same time safer.

The advantages that enamel coating provides are the following:

resists decay in any water, even sea water or containing nitrogen compounds;
inseparable from the metal, and this prevents the formation of corrosion under the coating;
does not age, it is wear-resistant;
enamel is resistant to temperature changes;
non-toxic and hygienic;
enamel is biologically neutral (it is not the best environment for bacteria to grow);
The coating technology is such that it is possible to apply enamel in containers of any size.

To prevent rust from appearing on the tank, anodes are installed - magnesium or titanium. They are fastened using a threaded part with a heating device.

What is it for?

Let's try to figure out why a magnesium anode is needed for a water heater.

Current flows from the anode itself to the damaged areas. Thus, due to the decomposition of the more active material, corrosion does not occur.

The anode, which is built into the tank, consists almost entirely of magnesium, so it is enough to check the structure once a year. It is necessary to comply with the check, since due to poor quality water the service life of the product may be reduced.

Magnesium and iron come into contact with water, but magnesium is more reactive than steel. Magnesium atoms leave the anode and produce oxide. Thus, the steel atoms remain intact and the tank does not corrode. That's the whole principle of its operation.

Magnesium anode for a water heater has a low price, and its use will be quite effective. When interacting with such a rod, the salt will not disappear, but will simply remain on its surface.

Titanium coated (active anode)

The operation of a titanium coated anode is slightly different. In this case, the current is supplied by a voltage source from outside. The stable current needed to prevent corrosion is supplied and regulated by external electronic control. The active anode functions as a supply and measuring electrode.

From time to time the current supply stops. During these minutes, the anode analyzes the state of the internal part of the structure for damage, and accurately regulates the strength of the current supply for restoration.

When a water heater with a titanium anode operates, it is not subject to destruction, and therefore does not need to be replaced throughout the entire life of the water heater.

On sale you can find a titanium anode with external power supply from Austria Email. Model: CORREX. It costs a lot - more than 15,000 rubles.

Replacing the magnesium anode

You already know how often you need to change the anode in a water heater: titanium does not require replacement during all the time of use, but magnesium should be checked on average once a year. If you use the device frequently - more than once a year.

New and corroded anode

During the replacement process, it is also worth removing scale from the inner surface of the tank and the heating element. This will extend the life of the heating device and improve the quality of the water.

Now let's look at how to change the magnesium anode in a water heater with your own hands. It doesn’t matter which manufacturer’s device you purchased, the cleaning process will not be radically different.

It is worth saying that replacing the anode in a water heater should occur if there are the following signs of a dirty tubular electric heater:

the boiler turns on and off more often;
there is a slight hiss during operation;
the water takes a long time to heat up, or does not heat up at all (after all, if it is covered with a coating of lime, then it takes more time and electrical energy to heat the liquid).

With your own hands

To replace the anode, the following work is required:

It is worth disconnecting the boiler from the power supply and shutting off the flow of cold water. Drain completely through the water supply point (it is recommended to connect a hose, since the water flow will be difficult to control and there is a possibility of flooding everything around).
The next step is to unscrew and remove the protective cover. It is better to take a photograph of the heating element with all its connections after removal, so that after all the work you do not get confused and restore the structure to its original form.
Then you need to unscrew all the nuts, remove the sensors, the flange and begin to carefully loosen the tubular electric heater. After you take it out, place a bowl where the water will drain.
The heating element in working condition is easier to clean, since the coating has not yet hardened and can be easily removed with a flat screwdriver. If the plaque nevertheless becomes hard, then it is dissolved in citric acid(50 grams of citric acid per liter of water - keep in solution for about two days).
After all the cleaning work has been completed, you need to unscrew the magnesium anode for the water heater and insert a new one. Assembly must be done in reverse order.

Now you know that you need to monitor the condition of the anode in the water heater and change it on time.

You can purchase magnesium anodes for water heaters in our store at favorable and low prices. We ship to any point in Russia, both cash on delivery and by courier or transport company. We deliver goods to shopping center free of charge. An order for the post office, namely, cash on delivery, as well as delivery by courier or pickup, imply payment upon receipt of the order. Payment by Sberbank card, delivery by transport company occurs with prepayment. Our branches are located in many cities of Russia, so getting an anode will be even easier and more convenient. Valid in the online store flexible system discounts, which can be found in the "Discounts" section. If questions arise regarding sizes, compatibility of anodes with water heater models, etc. you can consult in online help, by phone in the "Contacts" section, or write to feedback on email. We are always ready to help and choose the right magnesium anode for your boiler model, be it Ariston, Thermex, Garanterm, Etalon, Polaris or any other brand.

Description of anode rods

The magnesium rod eliminates corrosion from the internal walls of the tank, and also softens the scale that forms on the heating element during operation of the water heater. It is a magnesium alloy rod on metal pin with thread and screwed to the heating element flange, together with which it is inserted inside the water heater tank. The hole thread diameter ranges from M4 to M8 depending on the size and weight of the magnesium alloy on the stud. The larger the size and weight, the thicker the magnesium anode pin. The diameter of the magnesium anode varies from 14 to 25 mm. The length of the magnesium part without the pin varies from 140 to 660 mm.

Operating principle

The water entering the water heater contains soluble calcium and magnesium bicarbonates, which are present in it in the form of Mg2+, Ca2+, HCO3- ions. Magnesium is the first to react with water, since it is more active than iron and binds free oxygen formed during heating due to a multiple increase in the number of Mg2+ cations. When an anode is installed in the tank, it is not hard scale (CaCO3) that is formed, but soft scale (MgCO3 or Mg(OH)3), which is easier to remove when cleaning the water heater, or which itself falls to the bottom of the tank during operation of the water heater due to thermal expansion or contraction of the heating metal element. Over time, the anode will dissolve, so it is advisable to check or replace the magnesium anode once a year or follow the water heater manufacturer's instructions.

Is it necessary to install a magnesium anode in a water heater?

Modern boilers have tanks made of stainless steel, with titanium, porcelain glass, and enamel coating. In this case, the tank undergoes corrosion in the welds and begins to leak over time, so it is necessary to regularly replace the magnesium anode. If it was not present in the water heater initially, then it must be installed in the event that scale forms on the heater. In this case, the manufacturer most likely performed welding according to special technology or even made the tank one piece, without welds. Without an anode, hard scale forms, which has lower thermal conductivity. At the same time, the heating time and the amount of energy consumed increase, the efficiency decreases, and the metal of the heating element constantly overheats. Ultimately this leads to its rupture and failure. Therefore, timely and regular replacement of the anode will allow your water heater to operate for many years.

What to look for when choosing a magnesium anode?

The main selection criterion is the diameter of the thread on the stud so that the anode can be mounted on the flange of the heating element or nearby, if such fastening is provided. The second criterion is the length, since meter ones, for example, simply may not fit. The next criterion is thickness. Anodes with a large diameter may interfere with the heater tubes, although in this case the plate with the mounting hole can be bent. The next criterion is the length of the hairpin. This choice is rare, as certain electric heaters require a long stud to avoid hitting the heating tubes.
Let’s summarize and list the criteria for finding a suitable anode:

thread diameter on the stud;
length;
thickness or diameter;
threaded stud length.

Now almost every house and apartment has water heaters and boilers. And, of course, any owner, making such a purchase, hopes that the device will serve for a long time.

In order for the water heater to work well, it is very important to monitor its condition. One of the most important details is a magnesium anode. In this article we will look at what this part is intended for in a water heater, how it works and why you can’t do without it.

This part is coated with a magnesium alloy, inside of which there is a metal base with threads for attaching the anode. It is designed to protect the walls of the tank from rust and scale.

When working electric water heater The magnesium rod is subject to corrosion, the extent of which depends on the quality of the water and the frequency of use of the tank. If it is destroyed, it is easily replaced with another. Experts advise replacing the anode once a year. To understand how often to do this, you need to monitor the condition of the anode.

The principle of operation of this element is that magnesium is more active than iron, so it is the first to be destroyed. Most of the dirt that is cleaned out of the tank is the remains of the anode.

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Although electric water heaters are made of stainless material, they are susceptible to corrosion. Often the steel is not of the highest quality, plus the hardness and quality of the water plays a big role. When the first small cracks appear inside the boiler, corrosion occurs, and nothing can be done about it. But if a magnesium anode is working in the water heater, then it can resolve the situation.

Causes of corrosion:

Stainless steel is unable to withstand hard water.
The boiler consists of two elements that are welded together; due to this effect, the stainless steel loses its properties.

Some Thermex boilers have a glass-ceramic coating, which cannot be seriously damaged by bad water.

In indirect heating boilers, cathodic protection can be installed to combat corrosion, but it runs on electricity and must be connected separately.

The magnesium-coated rod prevents corrosion inside the boiler. This part also softens scale on the heating element, that is, it protects the water heater from damage.

Now the magnesium anode is sold together with the water heater. Even if the boiler is made of the most expensive stainless steel, with various coatings, the presence of this element is simply necessary, as it helps the device last longer and protects it from damage.

The rod degrades over time, but how long it lasts is affected by the severity of the water.

If the water heater does not have a magnesium anode, its destruction by corrosion begins, and if it is present, the entire oxidation process is directed precisely at this rod.