Teny magnesium anodes. Magnesium anode for water heater. What is a magnesium anode

Every owner of a storage water heater knows that it is necessary to periodically clean the internal tank of the boiler from rust and scale. In most cases, when carrying out preventative work it is necessary to replace the magnesium anode - the most short-lived element of the water heater.

The need to install a new part arises quite often - at least once every two years, so let's talk about why manufacturers install a magnesium anode in their products and what functions it performs.

Purpose of magnesium anode

First of all, let us remember that the main material from which the internal tanks of water heaters are made is steel. As you know, steel is an alloy of iron and carbon, so this factor is decisive in the issue of boiler durability. There is always a certain amount of oxygen in water, which actively begins to be released when it is heated. When the steel walls of the container interact with this oxidizing agent, the formation of iron oxides occurs, which we call rust.

This is usually what the heating element of a water heater looks like before starting cleaning work

If manufacturers didn't protect inner surface tanks with a layer of enamel or glass-ceramics, then their products would not be able to withstand even a third of their service life.

However, there are no ideal coatings. During operation, constant temperature changes lead to the appearance of microcracks in the protective layer, and the metal of the tank becomes defenseless against the oxidizing aqueous environment.

Of course, there are some boiler models whose internal tank is made of stainless steel, but this also does not guarantee long-term operation. The thing is that, according to the requirements for devices of this type, and in order to reduce the cost of products, manufacturers use food-grade stainless steel, which does not have sufficient durability.

During operation, they also corrode, although this takes a longer time. The problem with such tanks creeps up from the other side - welding is used in their manufacture. It is the welds that are the weak link of stainless tanks, since when heated to the melting point, the alloys burn out from the alloy - additives that provide those same anti-corrosion abilities. Leakage of such tanks most often occurs at the seams.

In order to further protect the metal surface of the tank from the harmful effects of oxygen, manufacturers install a magnesium anode in the tank. This element is a steel rod coated with a thick layer of magnesium alloy. Inside the water heater tank, the anode is fixed thanks to a threaded part and is most often placed next to the heating element.

Water heater protection mechanism

So, we figured out what a magnesium anode is for. It's time to find out how it protects metal from corrosion. To do this, remember the school chemistry course.

During operation, the iron from which the tank is made interacts with oxygen in the water. In this case, each of its atoms loses a pair of electrons, turning into a positively charged Fe++ ion. Subsequently, due to the potential difference, this ion leaves crystal lattice metal, forming iron oxide FeO. In this case, iron, accepting oxygen electrons, is an anode.

By installing a magnesium element in the tank, manufacturers are “killing two birds with one stone”:

During operation, the protective electrode is quickly destroyed, so it must be changed periodically. If this is not done, the service life of the water heater will depend only on the condition of the internal coating, material and wall thickness of the container, as well as temperature regime and water quality.

Magnesium anode requires replacement when worn more than 60%. This usually happens every 15 - 18 months of operation.

By this time, the rod is covered with deep craters, it becomes loose and crumbles easily. The element must be replaced with a rod with the same geometric parameters. After disassembling the water heater, do not be lazy at the same time to remove scale and dirt from the inner surface of the tank and heating element. This will significantly extend its service life and improve the quality of hot water.

Sooner or later, any owner of this device will have to replace a burnt-out heating element in a storage electric boiler. Don’t think that it will serve you for decades, no matter how high-quality and expensive the model is.

Heating elements fail for two reasons:

scale formation and burnout of the working element (heating coil)

corrosion and mechanical failure

Scale and cleaning of heating elements

Scale forms primarily in the presence of hard water. Just 1mm of scale gives 75% additional thermal insulation. Thus, the heating element under such a large layer of salts simply begins to overheat.

The first sign of scale formation is a distinct hissing or whistling noise.

When the noises become louder, but the boiler continues to work properly, do not delay cleaning, otherwise it may be too late.

Disassemble the boiler, as shown below, and begin cleaning. This can be done in two ways:

Cut off the neck plastic bottle 1.5 l and dilute the solution in it:

warm water 60 degrees

7 teaspoons citric acid

Soak the heating element in it overnight. After which, in the morning you clean off all excess. The result is sometimes simply amazing.

Corrosion water heating element

Why does the heating element body corrode and collapse? The fact is that the heating element in the boiler is equipped with a magnesium anode.

Without it, a galvanic couple is formed inside the titanium:

tank - heating element

And with a magnesium anode:

heating element - anode

Through this anode, all stray currents flow to the ground, gradually taking with them some part of the anode body. When it is completely destroyed, these currents begin to flow down the body of the heating element.

The growths on the heating element do not form evenly. Because of this, different parts of its copper shell acquire different expansion coefficients. As a result, surface tension is created, which breaks the shell of the heating element.

In many service centers, if the boiler breaks down completely, you may even be denied a warranty if you do not have a receipt for timely replacement of the anode.

Ultimately, corrosion becomes through and the working element burns out.

By the way, with the anode intact, the water from the tank may have a slight odor. When the smell disappears, this may be some indication of electrode corrosion.

Modern models have special sensors that monitor the condition of the anode.

With timely replacement of the anode and mandatory cleaning, your heating element will actually last several times longer. Grounding the housing also increases the service life of the heating element by at least two times.

However, for some reason many people lose sight of this point. Meanwhile, during intensive work, it is recommended to clean the boiler at least once a year.

It cannot be said with certainty that some models, for example Electrolux, Ariston or Gorenje, have a longer service life than Thermex or Indesit. It all depends on many factors:

amount of water consumed

the average heating temperature of this water, its chemical composition

is there grounding or not?

Checking the serviceability of the heating element

How can you understand that the heating element has burned out and it’s time to change it? If the indicator lights light up and show that the boiler is on, but it does not heat, this is only an indirect reason.

You can also check the presence of potential between zero and the body of the device. When the heating element is destroyed, its current-carrying spiral comes into contact with water, and through it the voltage reaches the boiler body.

It is better to take measurements with a multimeter, in measurement mode AC voltage. The dial can show either a couple of tens of volts or all 220V. This already indicates a 100% malfunction and the need to change the heating element.

If you have an RCD, as it should be in a normal circuit, then it begins to knock out when you try to turn on and supply power.

A correct RCD (not 30mA, but max 10mA) is a mandatory element of the circuit when connecting any boiler, otherwise the voltage can easily end up on the faucet, tap water in the kitchen and other unexpected places.

Draining water and disassembling the water heater

And so, when you decide that you still need to open it, the first thing you do is turn off the power by unplugging the plug from the socket. Then drain the water from the titanium. To do this, turn off the hot and cold water supply taps.

Unscrew the cold water hose by placing suitable container for draining.

If water does not flow from the removed hose, this indicates an air lock. We need to remove it. To do this, just slightly loosen the nut at the point where the hot water pipe connects to the pipe.

After draining, completely unscrew both valves from the titanium (hot + cold) to open the bottom cover and gain access to the heating elements.

There are modern models where the bottom cover is collapsible and to remove it, it is not necessary to touch the valve. It comes in the form of a plastic insert secured with several screws.

Disconnect the power wires, first remembering or marking with a marker which one is connected where. Better yet, draw a diagram. As a rule, all wires are colored and this will be easy to do. Otherwise, you can get confused in such a pile of wiring.

If you don’t want to draw anything, then just take a couple of photos on your cell phone. You will know exactly the location of all elements and wires.

After this, unscrew the nuts or screws securing the heating element itself around the perimeter.

You can unscrew them in any order, but you need to screw them in the same way as the engine head or the wheels on a car, that is, crosswise.

If you immediately tighten a nut all the way, this will cause the flange to bend and there will not be the required tightness. Consequently, the gasket will not hold and will leak.

Carefully pull the heating element out. It will be all covered in rust, and from the magnesium anode, except for a thin burnt piece of iron, there may be nothing left at all.

Flushing

After the heating elements are removed, the boiler itself must be washed clean water from all the rust and dirt that has accumulated inside. Therefore, for a quality replacement, the water heater still has to be removed from the wall.

Rinse the insides with an ordinary tap hose. Pour only a little water, since the boiler with a volume of 50-80 liters will still have to be lifted manually to drain all the scraps. Someone adds citric acid when washing, some don't.

Washing tip: It is best to rinse the tank in the bathroom, placing it vertically on a linen board. Twist the watering can from the mixer shower and insert the hose into the hole where the heating element was.

Replacing heating element and anode

After all cleaning procedures, proceed to reassembly. Keep in mind that the anode may not be included with the new heating element. Be sure to buy it separately and screw it into your seat.

It is especially worth noting that if two heating elements are installed in the boiler, then it is not always necessary to install two anodes.

One is enough for one electric titanium, even if you have at least five heating elements inside. The anode is not an accessory or component of the heating element. This is an element of protection for the boiler.

Please note that in the factory version, during the first disassembly, on the second heating element there is no place at all for mounting this anode.

Some claim that on tanks with stainless steel you can do without an anode, the main thing is to have them in specimens with walls made of glass porcelain.

However, the pattern of failure of boilers is usually the same: first the anode, then the heating element and then the housing.

You can install heating elements not only from the direct manufacturer of the boiler. For example, there is a company called Thermowatt, which produces some of the best heating elements on the market. The main thing is that the power, overall dimensions and seating fit.

Practice has shown that there is not much difference. The main thing here is the quality of the product (China or Italy).

When repairing, be sure to change the flange gasket. Here are some of their varieties for boilers Thermex, Ariston, Indesit, Gorenje, Electrolux:

Thermex Ariston Indesit Gorenje Electrolux

Some people are trying to save money here. Remove the old one and replace it with the new element.

However, a leak that will inevitably form in a month or two will make you regret such savings.

The flange nuts, as mentioned above, are tightened in a cross pattern. In this case, there is no need to use excessive force; you can inadvertently break the thread or tear the pin out of the body.

According to the marks sketched in the diagram, connect the power wires and replace the protective casing-cover. Before closing the cover, be sure to check all terminal blocks again, they should fit tightly and not loosen.

Filling with water and checking functionality

Hang the electric titanium in place. Connect the hoses and open cold water, start filling the tank. The hot water tap must also be open to allow air to escape.

At the same time, make sure that there are no leaks anywhere. As soon as water comes out of the “hot” tap, the boiler is full. There is no need to close the tap immediately; let all the “slurry” spill out and finally flush the tank and pipes.

Only when it goes pure water, turn off the mixer.

After this, the water heater must stand for at least half an hour or an hour so that condensation leaves all surfaces and there is confidence that there are no leaks.

You can then apply voltage by plugging the titanium into an outlet. To check the operation of the thermostat, use the control knob to force the adjustment to maximum and minimum.

In this case, the boiler on/off light should light up.

If the boiler operates quietly, without making any sounds, and it is not clear to you whether it is heating or not, you can check the energy consumption using the meter.

At maximum heating power of the heater, the counter will spin or blink much faster. This means that the heating elements work as they should.

The entire repair with the purchase of spare parts will cost you around 1500-2000 rubles. In any workshop that calls a plumber to your home, they will ask for at least 3,000-5,000 rubles for such work, and this does not include materials.

So self-repair can save you a significant amount of money, the main thing is not to make some mistakes.

Errors when replacing heating elements

1 Tighten the heating element fastening nuts in a circle.

As discussed in this article, this method will lead to bending of the flange and subsequent leakage. That is, you will have to remove the boiler from the wall again, unscrew everything and reassemble it again.

2 Application of sealant when installing the gasket.

No sealants should be used when replacing heating elements. Tightness should be created only by uniform pressing of the gasket material.

3 Using an old gasket.

No matter how intact it may seem, in any case, every time you open the heating elements, be sure to replace the sealing elements.

4 Replacing only the heating element without replacing the magnesium anode.

Even if you don’t find a suitable anode in your store, never install heating elements inside the tank without it. Not only does this reduce the service life of the heating elements, but ultimately it all ends in burning out the body of the boiler tank.

True, some expensive boiler models have titanium anodes with electronic potential removal.

They just don't require replacement. Therefore, before unscrewing anything, carefully study the product data sheet.

5 Control board.

When washing the tank and draining the water, be very careful; you can accidentally flood the electronic control board with the display, which is located on the side of the housing, with water. In this case, the boiler simply will not start after switching on.

You will search for the cause for a long time, ringing all the terminals, but it will lie literally on the surface. You can soak this board even with the boiler upside down.

Look closely at the hole where the lone control wire goes.

Water can simply flow through it directly to the electronics. So, it is best to close this hole initially, even before pulling out the heating elements, by pushing any seal there.

In this article I want to tell you why boilers and storage water heaters a protective magnesium anode is installed. The majority of water heaters are produced with metal tanks. Iron reacts with water. As a result, rust forms. But oxygen is required for rust to form. There is always some amount of air dissolved in ordinary tap water. When heated, in a steel water heater tank, air begins to actively release from the water. It begins to interact with the walls of the tank, gradually destroying them.
The magnesium from which the protective anode is made also tends to react with water. Only it is more active than iron. The oxygen released when heating water is first used to destroy the magnesium anode and only then, having completely oxidized it, begins to destroy the steel walls of your boiler. The main part of the dirt removed from the tank during the next cleaning is the remnants of the oxidized anode.

But what about the super enamel coating on the inner walls of the tank, which manufacturers love to talk about? It also plays a huge role in protecting the boiler from corrosion. But no one has canceled the laws of physics. When heated, metal tends to expand. The composition of the enamel is specially selected so that the coefficient of thermal expansion of the enamel coating coincides with the coefficient of expansion of the metal. But, all the same, during operation, microcracks appear on the enamel, especially at welding joints.

The fact is that when welding, the properties of the metal change slightly. The expansion coefficient also changes accordingly. It is in these places that invisible cracks form. Well, as you know, water will always find a gap.
By the way. The boiling point of water under pressure of six atmospheres is 158 degrees Celsius.
And so, the result.

The magnesium anode is the only protection of the tank against corrosion. This protection is passive.
The presence of grounding does not affect the properties of the magnesium anode in any way.
The magnesium anode does not affect the amount of scale on the heating element. This is affected by water quality.
If the anode is not replaced in a timely manner, the service life of the boiler depends on the quality of the enamel coating, the thickness of the tank walls and the operating conditions of the water heater.

And finally, the harsh truth about dihydrogen monoxide, also called hydroxyl acid.
Guess what it was? What are we talking about?

Take care of yourself. Follow safety regulations! Good luck!
Vladimir.

Owners of water heating tanks often come across information about a magnesium anode for a water heater, but only some people have an idea of what this part looks like and what functions it contains. In short, the main purpose of a magnesium anode is to protect against salt deposits formed due to water. It resists such an unpleasant process as corrosion of the internal walls of the tank.

Quite a few people can claim that the new generation of water heaters today are constructed from stainless steel. This is a reliable fact - the water storage tank is really made of this material. Why does stainless steel need corrosion protection? Several facts can refute theoretical statements about the resistance of this material to destruction when used in domestic conditions.

The first thing you should pay attention to: food grade stainless steel- This is a material with not the highest durability. Theoretically, stainless steel can withstand hard water with salt impurities, but only for a while. A couple of months, a year and a half, but no more. If really high quality stainless steel was used to make the tanks, their price would be too high. The device would acquire premium status and become affordable only for some. However, a water heater is a very affordable device that is very popular.
The next point is presence of seams between structural elements water heater. As a rule, the tank is made of two parts fastened to each other. Under the influence of heat, the joints quite often change their structure, and then the stainless steel loses its main functions. This is how corrosion appears.

Everyone knows that surfaces are coated with special substances, which are also designed to protect against corrosion. But they cannot be called reliable and durable. In addition, the closed environment of the tank and the temperature of the liquid changes periodically. Very hot water expands the metal, then contracts it as it cools. Under the influence of such metamorphoses, the protective composition stretches and loses its integrity.

Water heater device

Developer shortcomings and the problem of hard water

In general, it would be justified to shift the blame for the weak resistance to corrosion of the tank onto the shoulders of the manufacturer. After all, it is he who is responsible for observing all technical characteristics and must think through every aspect. Moreover, if the developer was unscrupulous and saved on materials, this could lead to formation of microcracks. Once they occur, the process can no longer be reversed.

Intense oxidation of the metal occurs, caused by interaction with oxygen that has penetrated into the fractures.

Looking at the table of electrochemical potentials, you can see what can begin during such a process. But unscrupulous companies do not waste time on this. As a result of economy or a trivial misunderstanding of chemical processes, a variety of materials are used in the production of heaters that are not able to withstand the load. Needless to say, such boilers will stop working pretty soon.

But not only manufacturers are responsible for this. Chemical composition of water, which determines its quality, is very far from ideal in some regions. But it is she who constantly interacts with the heating element and the walls of the boiler. It is to compensate for unfavorable inclusions in the water that a magnesium anode is needed in the water heater.

Tank corrosion

Operating principle of the anode

Imagine for a second that the tank is not equipped with an anode. IN similar situation is formed galvanic couple. This effect was discovered back in the eighteenth century. The coating of the body will take on the function of protecting against corrosion and for this reason will soon begin to deteriorate. This is due to the fact that the electrochemical potential of the tank wall material is much weaker than that of the others used during assembly of the unit.

Why such a part as a magnesium anode for a water heater?, is needed in the system? Its electrochemical potential will be even less than that of the body. It follows from this that the oxidation process will be directed towards it.

A magnesium anode for a boiler is included in the design of almost all models. If you examine the new part, it will have a smooth, silver-colored surface. After prolonged use in the tank, traces of corrosion will become noticeable on the pin. But the most important point– the walls of the tank will maintain their integrity.

Why magnesium

Finding an answer to this question worries many minds. The secret lies in the electrochemical potential. For a substance like magnesium, it is quite weak. Along with this, material cost allows it to be used in mass production without increasing the price of the final product. Apply it as consumables much more effective than sacrificing the walls of the tank. Why exactly is a magnesium anode needed in a water heater? He collects salt on himself. When it comes into contact with magnesium, it settles on the surface of the anode without causing harm to other parts.

Replacement process

Since the part is consumable, periodic replacement of the anode is necessary. It won't take much time and anyone can do it.

Purchase the required part from a specialized store or service center.
Remove the protective cover from the bottom of the water heater.
After dismantling the casing, you will see the temperature sensor and flange. They also need to be carefully removed.
Shake it slightly and pull out the heating element. It may not give in due to deposits formed. Apply slight force, but be careful not to damage the equipment.
Remove the old anode from the special socket near the heating element.
Quite often, instead of a whole anode, you can find there empty pin. Why is this happening? Due to the gradual destruction of the magnesium layer. Pull out this pin and free the socket.
At the same time, clean the heating element from scale or install a new one.
Insert the new anode and carefully reassemble the boiler to its original state.

As you can see, replacing a used magnesium anode in a water heater is not as complicated a procedure as it might seem. Don't forget to clean it periodically inner surface of the tank, and also regularly change the anode. This will help maintain the efficient operation of the device and increase its service life.

Modern storage water heating tanks (boilers) are usually made of stainless steel, less often of copper. This allows the heater to be used for a long period, but still, over time, the tank becomes unusable due to corrosion. To extend the life of the tank, you need a magnesium anode in the water heater. Why it is used can be understood if you find out how cathodic protection works.

Extend the life of your water heater with a magnesium anode

Anode device

The water heater element is a round steel rod coated with a 10-15 mm thick layer of magnesium alloy. The electrode is attached to a threaded connection to the bottom of the tank body next to the heating equipment.

In some boilers they are mounted on the top of the tank. The working length of the anode ranges from 14 to 66 cm. In addition to magnesium, titanium, zinc are used for their manufacture, or active electrodes connected to the electrical network are used.

Due to their electrochemical properties and low cost, magnesium anodes have gained great popularity. The boiler needs a kind of protector for the metal parts of the tank from exposure to oxygen and salts resulting from the heating process.

In this video we will learn about the anode devices:

Purpose of the element

During operation of the water heater, substances are released in the water as a result chemical reactions. Cathodic protection involves the deposition of all foreign substances on the passive anode. This is why this element is needed in the water heater. It performs the following tasks:

protects the tank and its parts from corrosion;
prevents the formation of scale on the heating element;
reduces water hardness.

During prolonged operation of the magnesium electrode, its gradual destruction occurs, but the chemical composition of the water does not change. This suggests that its use is absolutely safe for human health.

Therefore, it is very important to replace this part in a timely manner. To perform this procedure less frequently, it is necessary to monitor the quality of the water. The frequency of use of the boiler also affects the operating time of the anode.

Depending on all factors, this device can last from 1 to 7 years. It is possible to operate a water heater without an anode, but then the boiler will fail very quickly. By the way, when purchasing a new item, you should pay attention to the quality of the product.

An electrode made of cheap technical magnesium will fail very quickly, and during operation the water will acquire a characteristic smell of hydrogen sulfide.

Principle of operation

The principle of operation of the electrode is based on its activity, since magnesium in all compounds is a divalent metal, and the iron from which the tank is made is trivalent. In addition to corrosion, when heating water, scale forms due to settling salts of heavy metals.

Since magnesium has increased activity, the salt atoms interact with it, and not with iron. Therefore, the magnesium anode binds oxygen atoms and attracts like a magnetic material, iron salts. At the same time, the formation of calcium carbonate salts sharply decreases, and carbonic acid salts are formed from magnesium.

As a result, the scale becomes looser and can be easily removed when cleaning the unit. This prevents corrosion of the tank and the coating of the heating element. This process is called sacrificial protection, and the electrode is called anode-protector.

Currently, almost all manufactured boilers have a magnesium anode. For its long-term operation, certain measures must be observed. Here are some of them:

There should be no extraneous sounds when the heating element operates. If the boiler makes a quiet hiss, these are the first signs of scale and anode failure.
The condition of the magnesium anode must be checked at least twice a year. If minor damage is noticed on it, it is better to replace it with a new element.
It is best to use softer water in the heating system, which will greatly extend the life of the electrode.
If the boiler periodically turns on and off, but the water does not heat up, or its heating occurs very slowly, this is obvious signs presence of scale on the heating element.
Before you begin replacing the anode, you must close all taps and turn off the power to the boiler.