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Inefficient combustion of coal and wood is so common that it is considered the norm.

When burning, there should be smoke - every user with operating experience will confirm, because for many years this was the only way to burn. Fortunately, there are more efficient methods that help burn coal and firewood without smoke, stench and tar.

No matter how old and dirty your boiler is, whether you heat with cheap or expensive fuel, efficient fuel combustion will save you a lot of time and nerves and eliminate many boiler room problems, as most of them are the result of improper combustion techniques.

Smog - fuel flying in the air!

The stench and thick gray smoke are a constant element of winter. More and more people are talking about it - it's bad. But no one says that smoke is fuel flying into the air.

Smoke is unburned gases that are released from each type of coal and wood when heated.

This is not just smoke, but part of the fuel - each ton of coal contains 300 kg of gases, and a ton of wood contains more than 700 kg! The problem is that these gases are burned only at temperatures of 400-500C. At the right temperature, the gases burn, so the smoke turns into almost transparent vapors. This is the correct economical combustion of coal and wood.

Unfortunately, most users are wasteful with fuel — loading a large amount of fuel falls directly on coal.

The temperature in a boiler filled with a pile of cold fuel is too low to burn the gaseous component of the fuel. Therefore, gray clouds of suffocating gas fly into the chimney - coal dust, unburned wood fuel gases.

Problems associated with improper combustion of coal and wood:

•         large amounts of soot and tar;
•       clogging of the chimney;
•         gas explosions;
•       tar formed on the walls of the heat exchanger and chimney.

And above all, fuel consumption! In just one year you will burn a ton, two or more than you really need! Efficient combustion - how is it done?

The economical combustion of coal and wood is nothing new. This is the creation of conditions in the boiler under which fuel gases have the opportunity to burn, and (almost) transparent vapors should go into the chimney. There are several methods, which are shown in the following illustrations.

The figure below shows which methods are suitable for different types of boilers and furnaces.

The vast majority of boilers and stoves on the market (including fireplaces) are top-burning stoves - smoke exits at the top of the heat exchanger. In such boilers, you can use all three methods of clean combustion, burning from top to bottom is preferable. In top-bottom combustion boilers, too, but, as a rule, combustion from top to bottom is difficult.

Is it worth changing anything? Of course, because proper combustion will save you a significant — approx. 30% - the amount of fuel that costs a lot of money today. Calculate how much fuel is needed to heat your home and compare the consumption - find out how much you can save approximately.

Adding fuel in small portions

It is only necessary to change your habits a little, refuse to burn fuel from below, and the work of your boiler will improve.

The easiest way to get rid of smoke is to add fuel in small portions.

Small portions is a relative concept, the fuel should be enough to ignite without extinguishing (cooling) the combustion center. The more heat on the grate, the more intense the combustion center, the more fuel can be loaded without the risk of "extinguishing the flame". With the right portion of fuel, the worst thing that can come out of the chimney is translucent black smoke. There should be no thick gray smoke and overgrowth of the chimney with tar.

Burning «step by step»

Burning «step by step» can be called from the side, because in this case the combustion center moves in a horizontal direction. This method is a kind of compromise between top burning and typical bottom burning. It ensures continuous combustion by adding small portions, not quite clean, but still much better than when adding a large layer of fresh fuel.

How does combustion work?

Burning «step by step» begins with the ignition of a small amount of fuel on the grate. When this part of the fuel burns out, the coals are moved to the back of the boiler, and the next portion of fuel is placed so that there is contact with the heat, but the fuel should not cover it.

Fresh fuel in these conditions does not heat up as quickly as when burned from below, as hot exhaust gases do not pass through the layer. Instead, the fire gradually covers the entire bookmark and releases volatile substances from the fuel that have the ability to burn at high temperatures.

Comparison with other combustion methods

Burning «step by step» – an alternative between two other combustion methods.

Compared to bottom burning, it is much better. Even the addition of a large amount of fuel does not cause «clogging» of the combustion hearth and prolonged smoke.

Compared to burning from above, this method is slightly worse, since not all volatile substances released from the fuel pass through the coal layer and burn out accordingly. The situation is, however, much better than when the same amount of fuel is laid on coal.

Burning from top to bottom

Compared to the traditional combustion method, the cleanest and most efficient way of combustion.

How is top burning done

The task is to transfer the combustion center to the upper part of the furnace. The design of the boiler does not change, the air passes from the grate upwards. But now the combustion center slowly sinks down and the smoke from the cold fuel layer must pass through the fire, where it almost completely burns out. At the outlet of the chimney, almost transparent smoke is observed, which indicates the efficient combustion of fuel.

The entire combustion cycle is shown below. Top combustion is a cyclical process, that is, the fuel is ignited from above and completely burns out, only after that the next bookmark is made. The whole process is quite simple and the user only needs to change their habits a little.

Burners in feeder boilers operate in the same way as in top burning, but on a smaller scale, and therefore such boilers burn fuel cleanly and efficiently.

Test results: less smoke ­– less emissions

        Existing research in Western Europe shows that top-burning stoves and wood fireplaces reduce particulate emissions by more than 50%.

        Thousands of people who have been using the top burning principle for many years confirm noticeable fuel savings (approx. 30%).

Is top burning safe?

The top combustion method itself does not create new risks compared to the classical use of boilers and stoves (and even slightly reduces the problem of gas explosion or chimney fire). On what basis can we make such a statement:

• more than ten years of intensive use of this particular method in Poland on various boilers have not revealed any known problems;
• Overhead combustion is widely used in Western Europe;
• some of the upper combustion boilers, which in their instructions speak of this particular method of combustion, do not differ in design from those that do not have any records of this – the problem is not technical, but in the mentality of manufacturers.

The method itself is not complicated, but you need to be very careful not to do something you are not sure about. It will actually help to identify problems arising from installation errors or negligence in the operation of the heating system, chimney and boiler itself, which have not yet been detected.

The main risk with top burning occurs when too much fuel is loaded. If the boiler is not airtight or the power is cut off at the time of firing, the consequences can be more serious than the usual temperature rise or boiling.

In a properly installed heating system, this is safe, but not all systems are made correctly.

The most important point is the relative tightness of all boiler doors and Competent selection of the boiler by power.