What is combustion in a chimney?

What is combustion in a chimney?

One of the reasons we talk about what firewood you should use for the fireplace is to achieve good combustion. You’ve probably heard of this phenomenon when we refer to fire or the use of fuels to keep warm, as it is something inseparable. But do you know what combustion is in a fireplace? In this article, we will focus on discussing it to explain it in an easy-to-understand way.

The basic concept of combustion

Combustion is a chemical process in which oxygen is always present. When a fuel such as firewood or gas is subjected to the action of fire, oxygen ensures that several phenomena occur, among which heat and a continuous action of fire, which has just been ignited, stand out. If the supply of oxygen or the fuel is cut off, the process ends, and there is no more fire or heat.

Basically, this is what happens when a fireplace is lit. An air intake, or several depending on the model, allows the fire to have sufficient oxygen to sustain itself, as long as there is fuel to feed it.

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Technically, what is combustion in fireplaces and stoves?

Combustion in fireplaces and stoves is an exothermic chemical process in which a fuel combines with an oxidant, usually atmospheric oxygen, to release energy in the form of heat and light. This process is carried out in heating devices such as fireplaces and stoves to provide heat to interior spaces.

The chemical reaction of combustion can be described by the following general equation:

Fuel + Oxidant → Combustion Products + Energy (heat and light)

In the case of wood combustion, which is a common fuel in fireplaces and stoves, the chemical reaction involves the combination of cellulose, hemicellulose, and lignin (the main components of wood) with atmospheric oxygen. The reaction produces carbon dioxide (CO2), water vapor (H2O), energy in the form of heat, and often incomplete combustion products such as carbon monoxide (CO), particles, and volatile organic compounds (VOCs).

Stoves and fireplaces can operate with different fuels such as coal, natural gas, or pellets. The combustion of these fuels also involves the release of energy and combustion products similar to wood combustion.

In technical terms, the efficiency of a fireplace or stove refers to how effectively the device converts the energy contained in the fuel into useful heat. This can be influenced by various factors such as fuel quality, fireplace or stove design and technology, and device maintenance.

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Modern fireplaces and stoves often incorporate more advanced technologies, such as double combustion systems, to improve energy efficiency and reduce greenhouse gas emissions and atmospheric pollutants. These devices are designed to enhance combustion and heat transfer to the environment, resulting in more efficient and sustainable heating compared to older fireplaces and stoves.

Multiple Combustion Processes

What are we referring to when we talk about a triple combustion system or something similar? In reality, this type of combustion is a more intense process than normal and requires several elements to occur.
chimney combustion

When we talk about a double combustion fireplace or multiple combustion, we are referring to a system that has a main air inlet and other secondary inlets. In the case of double combustion, oxygen enters through another zone, which not only improves the fire’s draft but also allows the gases that were not consumed in the initial process to burn thanks to this new burst of air. When there is a third inlet, it is similar to the previous one and feeds the flame so that any remaining unburned gases can be consumed.

What stoves have combustion?

When we talk about combustion models, we are referring to all stoves and fireplaces that use fuel to produce heat, whether or not there is a visible flame. The only stove models that do not have combustion are electric ones, which heat through radiation, a very different process.

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chimney combustion

How to improve fireplace combustion

Considering that this chemical process ensures our home is in the best condition, it is advisable to do everything possible to make it efficient. There are several tricks for lighting a fireplace that we have discussed on other occasions, such as choosing suitable firewood or keeping the draft and air inlets in good condition to control the fire. All of this is very important since combustion must be as good as possible. Otherwise, incomplete combustion can occur, endangering the safety of those in the house at that time, either due to poisoning or the risk of a gas buildup turning into a tragedy, like the silent killer.