How to clean a boiler from tar

Types of waste is formed depending on what exactly you throw into the boiler for combustion to produce heat. The consequences of combustion. the formation of ash and ash on the walls of the unit, and other products. If the surface is not cleaned in time, the efficiency of the boiler becomes much lower.

The primary cause of soot is a lack of oxygen in the combustion process. If you use low-quality fuel, throw wet products into the boiler, or in order to save money, set the boiler to operate constantly at low levels, be prepared to deal with the soot. Overfilled furnace. also causes malfunctions.

Tar is formed if the combustion chamber has a low air flow and the unit is not properly set up. Low chimney also provokes the accumulation of tar.

The consequences of ignoring cleaning

If there are many harmful substances in the boiler and the user takes no action to eliminate them, the following negative processes occur:

  • The boiler starts to heat worse;
  • It becomes noticeably cooler in the house, even if you set the normal operating parameters;
  • the need to use more fuel arises;
  • the boiler operating life is shortened rapidly.

The benefit of regular cleaning is that it prolongs the life of the machine and keeps it running properly.

How often should you clean?

To determine the regularity of cleaning, it is important to consider the quality of the fuel material used.

If you do not save money and prefer to buy a proven fuel, the boiler can be cleaned once a month. If you choose affordable options, you need to clean every 15-20 days.

Periodic readings are approximate. The main criterion is the work of the boiler. Does not function as well as before? It is a good idea to clean out of sequence.

Ways of cleaning

As it has already become clear, cleaning is a mandatory process. It remains to figure out how to properly perform it. Four variants are practiced.

The first is the mechanical method, which involves the removal of dirt, using a set of specific tools, consisting of the following elements:

Sold in special stores and consists of tools of different sizes, allowing easy access even to the most hidden places. Get to work only after the boiler is completely cooled. And open the damper fully.

clean, boiler

When using wood as the main fuel for cleaning, follow these steps:

  • Warm up the unit. This is done to make it easier to clean the walls of the boiler from tar and tar. When heated, it’s much easier to do this because these types of dirt have a solid structure;
  • Take a spatula and thoroughly clean the walls of the unit;
  • After a thorough cleaning, allow the boiler to work for some time at a stronger mode than usual. Then the tar and tar residues will burn on the walls of the boiler on their own.

Chemical method

This is a thorough cleaning of the boiler, using a special chemical cleaner. There are two ways to do this.

The first option. pour the powder on the hot fuel. Since its composition has crystals that react with soot and tar, the impurities are destroyed under its action, and then fly away with the smoke.

The second option is to treat the walls of the boiler with chemicals. Apply to the soiled areas, wait for the time specified in the instructions, clean the unit from the residues of the products used.

clean, boiler

When cleaning be careful. Do not let the skin come into contact with the active substances. Wear gloves and goggles. Take care to purchase special clothing.

The next cleaning option is “soft blasting”

To implement it, you need to buy a special device, which inside has a solution made on the basis of chalk and baking soda. With this device the boiler is completely treated.

Steam cleaning is a steam treatment followed by a disinfection process. That is, not only clean the walls of the boiler, but also rid the unit of bacteria. Steam generator feeds under strong pressure steam, which softens the impurities, and they fall off the walls of the boiler. It is used for wood and pyrolysis equipment.

Folk methods are no less popular among the population, who do not want to spend money on buying special devices and substances. Many users simply pour salt on the burning wood, after which the soot comes out of the boiler together with the smoke. Many people also put pre-dried potato peelings on the hot fuel. During combustion, starch is released, which significantly reduces the level of contamination.

Heating the boiler with aspen wood

Since this method causes a large flame, it simply burns the soot from the inside. Today this method is not recommended by professionals as a fire hazard. So it is important to be careful.

The choice of cleaning method depends on the option that was most convenient for you personally. And how much money are you willing to spend on it. Also remember that the effectiveness of the methods depends on the regularity of cleaning. It’s much easier to remove a thin layer of dirt right away than it is to deal with the consequences of neglecting unit cleaning for a long time.

And remember that it is better to spend time and money on cleaning than to end up having to buy a new unit.

If the boiler is not cleaned regularly, the negative effects cannot be avoided. First of all, the heat output is reduced. The room will heat up slowly and the heat will not spread evenly. The next disadvantage is that you will need to use more fuel, respectively, will increase costs.

A solid fuel boiler that is not cleaned in time from ashes, soot and tar will not last long at all, because its main elements, responsible for high-quality heating will quickly fail.

Regular cleaning of the pyrolysis boiler will not only ensure its efficient operation, but also increase its service life.

The frequency of solid fuel boiler cleaning procedures depends on the quality of the fuel used.

If you are using high quality wood, coal, etc.д., it will be enough to clean the unit once every 30-40 days. If you use low quality fuel with high humidity, then the boiler must be cleaned at least once every two weeks.

In any case, you need to constantly monitor the operation of the solid fuel boiler. If you notice any malfunctions and failures, carry out an unscheduled cleaning, regardless of when it was last done.

About pellet boilers features you can read here.

How to keep the boiler from getting very dirty

In order to prevent the formation of tar, it is necessary to heat the boiler with the maximum amount of air, which in turn ensures a complete combustion process. This mode ensures the operation of the solid fuel boiler with maximum efficiency. It is necessary to buy wooden fuel a year before the heating season, and store it in a dry place so that it had time to dry up during this period. It is allowed to use wood with humidity of 20% or lower.

Normal solid fuel boiler (non-condensing type), should operate at a water temperature on the return pipe of the heating circuit at least 55 C. This mode is maintained by the three-way valve with the thermostatic head. Such a temperature schedule of the heat carrier return from the consumer will prevent the formation of tar and dew point, at which the destructive acid caused by condensation accumulates in the flue ducts.

Cleaning methods

Probably every boiler owner wonders what to clean the unit with and how to do it properly. There are four basic ways to clean a boiler from soot, tar and tar. Their features are the following important points.

Mechanical cleaning. Represents the cleaning of the solid fuel boiler from the products of combustion with a special set of tools, which includes the following elements:

  • poker;
  • scrapers of different sizes;
  • Spatulas of various widths;
  • metal brushes;
  • ruffles of various configurations, you can buy them in any store, for example here:

It is worth understanding that cleaning the boiler from soot with these tools is made only when the unit has cooled down completely.

Thus, we see that the cleaning of solid fuel boilers from soot, tar and tar can be done with your own hands.

An informative article on flushing the heating system of a private home can be found here.

“Soft blasting”. This method is considered an American technology for cleaning pyrolysis or wood-fired boiler of combustion products.

Its essence is that using a special device a special solution consisting of chalk and baking soda is poured onto the dirty surfaces of the boiler.

Steam cleaning of the boiler. The essence of the method is that using a steam generator, the walls of the boiler are treated, and the boiler unit is also disinfected.

Regularity of cleaning procedures

The interval between cleaning wood, pellet or pyrolysis boilers depends primarily on the quality of the fuel material:

  • If high quality fuel is used, the boiler unit should be cleaned once a month;
  • in the case of using fuel of low quality and with a high degree of humidity, cleaning should take place once in 15-20 days.

Despite the above terms, you should always monitor the operation of the solid fuel boiler, and in case of irregularities in the operating rhythm, you can perform an unscheduled cleaning.

You may be interested in the article about two-circuit solid fuel boilers. An interesting article on how to make a long combustion boiler with your own hands, read here.

The interval between cleanings of wood, pellet or pyrolysis boilers depends primarily on the quality of the fuel material:

  • if high quality fuel is used, the boiler unit should be cleaned once a month;
  • In the case of low quality fuel with a high degree of moisture, cleaning should take place once every 15-20 days.

Despite the above terms, you should always monitor the work of the solid fuel boiler, and in the case of a disturbance in the working rhythm, you can perform an extraordinary cleaning.

Interesting article on how to make a long combustion boiler with your own hands, read here.

Boiler Cleaning Ways

You can find quite a few articles and videos on the Internet about how to clean a solid fuel boiler from tar. The most important thing about this procedure is its regularity. Even if you remove dirt with all care, to the last particle, but doing it at intervals of six months, it is unlikely to improve the work of the heating device. There are 3 main methods of cleaning combustion products from the internal walls of the boiler, with each of which you must familiarize yourself in detail before starting the procedure.


It involves the use of special tools: pokers, metal brushes and scrapers, scrapers and blades of various sizes. The basic steps of operation are as follows:

  • Melt the boiler, so that the high temperature softens the hardened tar and makes it easier for it to come off the walls.
  • Completely turn off the device, wait for it to cool down a bit and be sure to leave the damper open.
  • Using a full set of tools, carefully remove dirt from the inner surface of the combustion chamber.
  • Once the cleaning is complete, melt the boiler again, allowing the remaining tar particles to burn out completely.

If as a fuel material was used wood from resinous species of trees, and a thick layer of hardened carbon deposits has accumulated on the walls of the appliance, you need to prepare for the cleaning procedure in advance. You will need ½ bucket of anthracite or about 15 kg of dry, non-smolly firewood, which can burn out most of the greasy deposits and make further mechanical cleaning much easier.

During the operation it is necessary to use metal tools with great care, so as not to damage the walls of the device by its sharp edges.


Based on the use of special products for cleaning solid fuel boilers from tar, soot and tar. The chemical method of removing impurities from the surfaces of heating equipment is very popular, as it does not require much time and physical effort.

There are two methods of chemical cleaning:

  • Contaminated boiler walls are treated with an acid-based cleaner that quickly breaks down deposits and it is very easy to remove them mechanically.
  • The chemical compound is poured directly on the burning fuel. Crystals of the special agent in this case react with tar and soot, destroy them and remove from the boiler through the chimney.

To treat the combustion chamber from the inside with a chemical agent for cleaning solid fuel boilers, the composition must be heated to a certain temperature and, using a pump, supply into the system. As a reagent most often act:

  • Adipic acid.Mixed with water to obtain a solution of a certain concentration which is slowly poured into the boiler using a pump. Interacting with the products of combustion, the acid dissolves them and converts them into salts. As soon as they precipitate out, the remaining contaminants are washed away with clean water.
  • Sulfamic acid.Also intended for preparation of a solution which is fed into the boiler under pressure. The layer of deposits formed on its internal walls, under the influence of the reagent is destroyed and easily removed by running water.

The choice and concentration of the cleaning agent depends on the nature and extent of the contamination. After treatment with chemicals, the inside of the furnace chamber must be thoroughly dried and ventilated before starting the unit.

When using chemicals to remove tar deposits, it is important to follow safety rules:

  • Work with reagents only when wearing rubber gloves and a mask;
  • Do not increase the concentration of the solution at your own discretion;
  • Do not use chemicals with an expired shelf life;
  • Limit access of children and pets to the cleaning chemicals.

On the use of a special solution for the treatment of contaminated surfaces of the boiler is also based on another method of cleaning from tar. soft blasting. It requires a special device that allows you to evenly apply the reagent to the walls of the combustion chamber, and the cleaning composition itself contains chalk and baking soda. Carry out chemical cleaning of heating equipment, experts recommend only in cases where there are very many deposits accumulated, and it is not possible to cope with them by gentle methods. This is due to the fact that any reagents affect not only the dirt, but also the metal surfaces, so their frequent use can have undesirable consequences.


This method of cleaning requires a steam generator used to treat the solid fuel boiler from the inside. The essence of the method is simple: steam is fed to the walls of the combustion chamber under high pressure, which softens the deposits and facilitates their removal. Steam cleaning gives the possibility to get rid of not only the dirt layer, but also the fungus and mold that often attack the internal surfaces of the heating equipment.

How often the inside walls of a solid fuel boiler need to be cleaned is determined primarily by the type of raw material used. If high quality dry wood or coal is used in the firebox, it is recommended to clean the tar layer not more often than once a month or 40 days. When the fuel is wet or low, this procedure must be performed more frequently. every 15-20 days. In parallel, it is necessary to monitor the functioning of the device. if the rhythm of work is disturbed, it is better to carry out unscheduled cleaning. Inspect the inside walls of the boiler and chimney weekly to detect accumulation of tar and soot and take action.

Read more about cleaning heating boilers on our Zen-channel.

Why in a solid fuel boiler tar is formed

During the combustion of any fuel on the inner heating surfaces of the boiler soot and tar deposits accumulate. They are good insulators and with their considerable thickness, reduces the heat transfer from the internal heat exchanger to the heated water. In addition such deposits clog the passage sections of the chimney system, as a result the speed of flue gas flow decreases in them.

This process contributes to overheating of structural elements of the boiler with their subsequent failure. Soot, in addition, has the potential to ignite in the flue ducts, creating a hotbed of combustion in the home. For prevention and in order to prevent such dangerous processes from occurring, every heating boiler should be subjected to periodic cleaning of heating surfaces and flue ducts. And owners of such equipment should know how to clean the boiler from tar.

Combustion products and their cause

Byproducts that appear in the combustion process are:

The reasons for the appearance of these substances are the following important points


  • Causes of soot:
      There is not enough oxygen for the combustion process;
  • the temperature of fuel combustion is too low.
  • Factors affecting the appearance of tar:
      low-quality fuel is used;
  • The fuel material has a high degree of moisture;
  • The boiler is operating at a low temperature;
  • too much fuel is loaded into the furnace.
  • The tar appears in the following cases:
      poor air flow into the combustion chamber of the pyrolysis boiler;
  • Improper design of the unit;
  • low height chimney.

As we can see, the main causes of harmful substances are bad fuel and technical organization of the combustion process.Specialists advise: use only high quality fuel. otherwise the wear and tear of the boiler will rapidly increase.

Information on flushing the heating boiler can be found at this link:

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