Everyone knows that a magnesium anode is built into the boiler, but few people know why it is needed. The anode neutralizes water by taking in salts poor quality water. Plus, the anode converts hard deposits into soft scale. If the boiler were without an anode, then the boiler tank would turn into a center of corrosion. After all, nothing lasts forever. The tank, which is made in most cases from stainless steel, undergoes changes under conditions of long-term operation in hard water conditions. In addition, the butt joints of the tank under conditions of elevated temperature change their structure and are destroyed. chemical reactions pass constantly as the boiler is used.
The built-in anode gives the possibility to use the boiler much longer and reduce energy costs.
Some interesting advantages of various manufacturers
The Gorenje company conducted an experiment by installing modern anodes on old models of water heaters. This had a positive effect on the operation of the devices. The efficiency has increased, which means that the water heating time has significantly decreased even with a full tank.
Atlantic also experimented with models from its brand. Installing the anode various models, experts were convinced of the increase in the service life of the heating element by as much as half.
The Thermex water heaters have a long service life, since some devices have glass-ceramic coatings. Along with competitors, such a unit is not afraid of bad water.
Principle of operation
The first company to use a magnesium anode was Ariston. It has always been distinguished by the production of high-quality household equipment.
Magnesium is a metal that is more reactive than steel. By placing a magnesium anode in the boiler, the water is saturated with the cations of this element. They bind the oxygen formed when the water is heated, which protects the boiler from corrosion.
However, an excess of this split element entails the formation of loose scale due to binding with carbon anions. But it is easy to remove from the boiler. Scale forms as an insoluble precipitate and settles on the anode itself.
Why does magnesium anode fail?
When the boiler is running, the magnesium anode is consumed. This is due to the fact that corrosion in the tank is neutralized. If you use the boiler frequently and the quality of the water you use is poor, get ready to replace the anode soon.
Replacing the magnesium anode
magnesium anode is a magnesium alloy plated metal pin with an approximate thickness of 15mm. A threaded metal stud is applied to the end of the cylindrical rod. The length of the pin is 140-660 mm, and the rod is 14-25 mm.
The technical serviceability of the magnesium anode must be taken under visual control. Worn anode can adversely affect the performance of the boiler.
All manufacturers have different anode designs. This fact condemns consumers to purchase only the anode that fits the boiler model. When using the boiler for more than 15 months, the anode should be removed and checked for wear. After this lifetime, the anode is likely to be worn out and should be replaced. The anode is unscrewed with a pin from the threaded hole of the heating element flange.
The process of replacing the magnesium anode, as well as cleaning the ten, are shown in the following videos.
There are several criteria that it is time to replace the anode or try to clean the device:
- when the heating device is turned on, protection is activated. This is due to a thick layer of scale on the heating element;
- there is no water heating when the boiler is running;
- the boiler body is energized.
- Check the device by ear frequently. If you hear a hiss when heating, then the heating element does not have enough contact, and it began to be covered with a coating.
- After some time, we advise you to look inside the boiler. If you see 50% destruction of the anode, then you can already look for a replacement to definitely protect the water heater.
- Do not allow the device to operate without an anode.
- Try to clean the boiler more often than prescribed in the product passport. This prolongs its service life.
Description of anode rods
The magnesium rod eliminates corrosion of the inner walls of the tank, and also softens the scale that forms on the heating element during the operation of the water heater. It is a magnesium alloy rod on a metal threaded stud and is 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. How more sizes and weight, the thicker the magnesium anode stud. The diameter of the magnesium anode is from 14 to 25 mm. The length of the magnesium part without the stud is 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 amount of Mg2+ cations. When the anode is installed in the tank, not hard scale (CaCO3) 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 the 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, glass-porcelain, enamel coating. AT this case The tank corrodes at the welds and begins to leak over time, so the magnesium anode needs to be replaced regularly. If it was not originally in the water heater, then it must be installed in the case when 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 is formed, which has a lower thermal conductivity. This increases the heating time and the amount of energy consumed, reduces the efficiency, there is a constant overheating of the metal of the heating element. In the end, this leads to its rupture and failure. Therefore, timely and regular replacement of the anode will allow your water heater to work 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 fixed on the heating element flange or nearby, if such fastening is provided. The second criterion is the length, since meter ones, for example, simply may not fit. Next criterion- thickness. Anodes with large diameter can touch 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 keep the heating tubes out of the way.To summarize and list the criteria for finding a suitable anode:
- thread diameter on the stud;
- length;
- thickness or diameter;
- threaded stud length.
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 the owners of water heaters to clean the tank from scale and corrosion, it is required to replace the anode. But what is an anode, a person does not know. From the article you will learn what it is and in general why it is needed in a water heater.
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Water heater anode
To begin with, let's clarify 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 all, the formation of oxide begins.
In order to protect the inner surface of the water heating structure, protective enamel is used. It makes the service life longer and at the same time safer.
The benefits of enamel coating are as follows:
- resists disintegration in any water, even in sea water or with the content of 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 extremes;
- non-toxic and hygienic;
- enamel is biologically neutral (this is not the best breeding ground for bacteria);
- coating technology is such that it is possible to apply enamel in containers of any volume.
To prevent rust from appearing on the tank, anodes are installed - magnesium or titanium. Their fastening occurs with the help of a threaded part with a heating device.
What is it needed for
Let's try to figure out why you need a magnesium anode for a water heater.
From the anode itself, current flows to the damaged areas. Thus, due to the decay of the more active material, corrosion does not appear.
The anode, which is built into the tank, consists almost entirely of magnesium, so it is enough to check the design once a year. It is necessary to observe the check, because due to low-quality water, the service life of the product may be reduced.
Magnesium and iron are in contact with water, but magnesium is more active 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 work.
The magnesium anode for the 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 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 the outside. A stable current, which is needed to prevent corrosion, is supplied and regulated by an external electronic control. The active anode functions as a supply and measuring electrode.
From time to time the power supply stops. In these minutes, the anode analyzes the state of the internal part of the structure for damage, and precisely regulates the strength of the current supply for restoration.
During the operation of a water heater with a titanium anode, it is not subject to destruction, therefore it does not need to be replaced throughout the entire life of the water heater.
On sale you can find an externally powered titanium anode from Austria Email. Model - CORREX. It costs a lot - more than 15,000 rubles.
Replacing the magnesium anode
How often you need to change the anode in the water heater, you already know: titanium does not require replacement during the entire period of use, but magnesium should be checked on average once a year. With frequent use of the device - 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 heater and improve water quality.
Now let's look at how to change the magnesium anode in the 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 the replacement of the anode in the water heater should occur if there are the following signs of a contaminated tubular electric heater:
- the boiler turns on and off more and more often;
- there is a slight hiss during operation;
- the water heats up for a long time, or does not heat up at all (after all, if it is covered with lime, then it takes more time and electrical energy to heat the liquid).
DIY
To replace the anode, the following work is required:
- It is worth disconnecting the boiler from the power supply and blocking the flow cold water. Drain completely through the water supply (it is recommended to connect a hose, as the flow of water 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 picture of the heating element with the entire connection 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, put the bowl where the water will drain.
- The heating element in working condition is easier to clean, since the plaque has not yet hardened and can be easily removed with a flat screwdriver. If, nevertheless, the plaque has become solid, then it is dissolved in citric acid(50 grams of citric acid per liter of water - soak in solution for about two days).
- After carrying out all the cleaning work, 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 are aware that you need to monitor the condition of the anode in the water heater and change it in time.
Each water heater has a sacrificial anode. However, many people not only do not know what it is for, but also what it looks like.
Because of this, the boilers fail much earlier than the manufacturer expected.
The magnesium anode is a thick rod made of this non-ferrous metal, installed inside the boiler tank.
Most often it is attached next to heating element on one base, so that in case of maintenance it was possible to remove both the electrode and the heating element with one movement. But in some models it is installed separately.
Why is it needed?
The magnesium anode performs two functions in the water heater:
- protects the body of the device and additional elements from corrosion;
- makes scale on the heating element loose, less durable.
The first function is the main one, the second one is a nice bonus. Modern boilers are made with galvanized or stainless steel bodies. Additionally, their surface is protected by special paints.
It may seem: why is this element there, if the steel is already well protected? But in any case, sooner or later the metal begins to rust. Even stainless steel is subject to corrosion at the welding site or under the influence of acids, salts.
Protective paint with constant heating and cooling becomes covered over time small cracks, through which water enters the metal, after which the destruction of the metal is a matter of time. Galvanization also has its resource.
Thus, without additional protection the water heater tank starts to rust after a couple of years.
The exact service life before a leak occurs depends on the intensity of use and chemical composition water. The service life is negatively affected by the presence of salts and acids, the richness of water with oxygen.
The principle of operation of the sacrificial anode is based on the galvanic interaction of conductors. Iron is less electronegative than magnesium, therefore, in the presence of an electrical bond, the former does not oxidize in the presence of the latter. In other words, the magnesium anode "pulls" oxygen ions towards itself.
As a result, as long as there is magnesium in the tank of the water heater, the steel body remains intact.
At the same time, this element facilitates the fight against scale.
The main element that pollutes the surface of the heating element is calcium salts, most often carbonates.
Magnesium cannot protect against this scourge, but it makes it less of a problem.
When the anode interacts with carbonates, substitution occurs, as a result, magnesium salts are deposited on the heater, which are distinguished by a loose and soft structure.
They are very easy to remove mechanically without risking damage to the heater itself.
Replacement
The magnesium anode protects the iron from oxidation by pulling oxygen towards itself. Thus, during operation, it gradually oxidizes itself, dissolving and breaking down.
That is why the second name of this method of protection is “sacrificial electrode”.
So that the protection does not weaken, the electrode must be changed periodically.
But this period can vary greatly depending on how intensively the device is used, how many liters of water are distilled through it per day, week.
Another very significant factor is the hardness of the water. The more hydrogen cations in the water, the lower its pH, the more intense the oxidation of the metal. Additionally, the destructive effect is exerted by mechanical particles that scratch the surface of the water heater body and the electrode, reducing its resource.
Therefore, it is advisable to install plumbing system a water softening filter and almost certainly a coarse filter.
Personal electrode service life is calculated empirically - at first the condition of the magnesium anode is checked every 4-5 months. By finding out how long your electrode lasts, you can reduce the number of checks.
The check is performed as follows:
You should not use a boiler without a sacrificial anode, because without it the life of the device is reduced several times.
Monitoring the condition and periodically replacing the sacrificial anode is a small concern that allows you to multiply the life of the heating device.
The cost of this element of 150-700 rubles is negligible in comparison with the price of the boiler itself. At the same time, do not forget that the rusting of the container ends with its leakage, which can lead to flooding of the neighbors. As a result, an attempt to save on a small electrode can result in thousands of losses.
In this article I want to tell you why in boilers and storage water heaters a protective magnesium anode is installed. The main part of water heaters is produced with metal tanks. Iron interacts with water. The result is rust. However, rust requires oxygen to form. In normal tap water there is always some air dissolved. When heated, in the steel tank of the water heater, air from the water begins to actively stand out. It begins to interact with the walls of the tank, gradually destroying them.
Magnesium, from which the protective anode is made, also tends to interact with water. Only it is more active than iron. The oxygen released during water heating is primarily spent on the destruction of 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 that is cleaned out of the tank during the next cleaning is the remains of an oxidized anode.
But what about the super enamel coating of the inner walls of the tank, which manufacturers love to talk about so much? It also plays a huge role in protecting the boiler from corrosion. But, nobody canceled the laws of physics. Metal tends to expand when heated. The composition of the enamel is specially selected so that the coefficient of thermal expansion enamel coating coincided with the expansion coefficient of the metal. But, anyway, during operation, microcracks appear on the enamel, especially in the places of welding joints.
The fact is that when welding, the properties of the metal change slightly. Accordingly, the expansion coefficient also changes. It is in these places that cracks that are invisible to the eye are formed. Well, water, as you know, 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 corrosion protection for the tank. This defense is passive.
- The presence of grounding does not affect the properties of the magnesium anode.
- The magnesium anode does not affect the amount of scale on the heating element. This is affected by the quality of the water.
- If the anode is not replaced in time, 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. Observe the safety regulations! Good luck!
Vladimir.
