Table of Contents
- How do I calculate the power I need from a fireplace? >
- What is triple combustion in a stove or fireplace? >
- Are wood stoves environmentally friendly? >
- Why does tar come out of chimney pipes? >
- How can air enter through the cap be prevented? >
- What causes can cause smoke to come out of the chimney itself? >
How do I calculate the power I need from a fireplace?
To calculate the power needed in the stove or fireplace for the room where you want to install it, it is necessary to take into account some variables, such as the space to be heated, the thermal insulation nivel of the room and the region where you are, depending on whether it is a cold or temperate area. In addition, the performance of the stove itself must be taken into account to assess all these parameters.
As a reference, we indicate these coefficients to calculate the power you will need:
Room with poor thermal insulation:
- The house is in cold zone: 0.08 kw/m3
- The house is in warm zone: 0.05 kw/m3
Room with good thermal insulation:
- The house is in cold zone: 0.05 kw/m3
- The house is in warm zone: 0.04 kw/m3
We explain it with an example: let's suppose we have a living room where we want to install the fireplace. The living room measures 60m2 and is 2.75 meters high.
The volume of the living room is V = 60 x 2.75 = 165 m3
Our house is located in a cold area and is also quite old and has poor thermal insulation, so the coefficient to be used is 0.08 kw/m3
The power we will need will be: P = 165 x 0.08 = 13.2 kw
Therefore, we will look for a fireplace or stove that is around this power to ensure that we can heat the volume of the room where we want to install it.
All manufacturers recommend not exceeding the capacities of the fireplace or stove, that its power is not much higher than necessary, since there is a risk of having to use the fireplace or stove at a lower power than recommended, so as not to overheat the room, which would lead to low combustion and, therefore, to higher emissions.
What is triple combustion in a stove or fireplace?
To understand what triple combustion is all about, it is best to start with the most basic thing that all fireplaces have, which is standard or simple combustion.
Standard combustion. The first combustion in a chimney is carried out with the entry of primary air that occurs through the ash collection box located under the grill where the wood is placed. For this reason, when we open the drawer more, it is possible to increase the flame and the burning of wood.
This first combustion through the primary air intake is found in all stoves and fireplaces, with the air in the room entering under the wood that we have introduced. With the installation of the smoke outlet, and with the combustion process, a depression is generated in the combustion chamber that causes the air to tend upwards, generating the air current that supplies oxygen to the combustion process.
To improve this combustion process, different systems have been added to add oxygen at different heights, so that by means of the entry of secondary air, oxygen can be added at mid-altitude, and improve the burning process. This secondary air intake, different from the primary one, is found in all those fireplaces that have Double Combustion.
This air intake, which is usually halfway up the flame, increases the performance of the stove, improving the process, and emitting less waste.
This data already allows us to differentiate cheap stoves and fireplaces from those that have greater efficiency, and that will be more profitable over time.
In addition, there are even more efficient fireplaces and stoves, which have taken the combustion process to the best levels, introducing air into the upper burning area, with triple combustion.
It is clear that this type of stove will not be the cheapest, but without a doubt they are the most efficient, so in the medium term, they will be the most economically advantageous, since they will consume much less wood than the rest.
Are wood stoves environmentally friendly?
In an increasingly technological world, the imperative need to take care of our environment makes us increasingly rethink the systems we choose for our well-being.
Firewood is a renewable energy that responds to the energy and environmental challenges of the century in which we live.
Throughout its life, a tree grows thanks to sunlight, water, mineral salts and CO2. It naturally accumulates the sun's energy and gives us the oxygen essential for life.
The amount of CO2 released during the combustion of wood is not greater than that which would be emitted by its natural decomposition. Therefore, we are dealing with a type of energy that respects the natural cycle of millions of years. The combustion of wood does not increase CO2 in the environment, so it is an ecological energy that does not participate in the greenhouse effect.
By buying a wood stove, you are helping the environment, you will have economical heating, and you will enjoy that flame show that no other type of heating can offer.
Why does tar come out of chimney pipes?
When wood is burned in our stoves or fireplaces, acids of different types are generated that combined with humidity form the waste known as creosote, which adheres to walls and doors in fireplaces. If too much build-up, especially in the flue pipes, combustion becomes more complicated and the chimney does not function properly.
Creosote is a thick, viscous, caustic black oil that we usually call tar. When a large amount is generated and it is in a liquid state, it usually comes out through the joints of the smoke outlet pipes, dripping little by little, and staining everything in its path.
Unfortunately, we cannot avoid this process, our fireplace will generate this type of waste continuously, however, it is possible to reduce the amount of this type of waste very easily. For example, opening the draft to the maximum when we light the fireplace, and maintaining a few minutes after lighting. The wood will be consumed faster at first, but the vapours will burn sooner and therefore the degree of humidity inside the pipes will be lower.
It is also important that the firewood we use is as dry as possible, so that this harmful moisture is not added in the combustion process.
Chimney sweep logs are usually used to clean these substances. Manufacturers recommend continued use, for example, on weekends, to maintain good health of the smoke outlet pipes. It is very important to clean at the end of the season, when we forget about our stove, and to go to a manual cleaning system by professionals if we detect that so much material has adhered to the walls that we cannot remove them with chimney sweep logs.
How can you prevent air from entering through the cap?
In many areas where there is continuous wind and in addition to great strength, the wind enters through the pipes and generates smoke inside the house, causing many inconveniences. For most cases, it would be sufficient to install an anti-plaster cap instead of a standard one, which limits the entry of air through the outlet area.
There are also other caps that act as weather vanes and rotate with the wind acting as a screen and preventing air from entering the fireplace itself.
As a general rule, installing this type of caps, you would have solved this problem.
What causes can cause smoke to come out of the chimney itself?
The causes why the smoke instead of following the path that has been designed for its extraction, comes out of the chimney or stove itself are several, in osaciones it is enough to solve one of them, but in others, several causes come together that will have to be solved together.
The reasons why we should ask ourselves are:
- Is the smoke evacuation duct internal or external to the home? Is it insulated or simple?
- Does the fireplace have clean air from the outside?
- What is the height from the fireplace hearth to the cap?
- When does smoke come out of the chimney door?
- What kind of cap does the fireplace have?
The air intake is a fundamental aspect for all fireplaces and stoves, so that combustion is carried out correctly. Having good ventilation will help maintain a good supply of oxygen to the process, and will reduce the amount of fumes generated. To give an approximate figure, for each kg of wood, 8 m3 of oxygen are required, which combustion itself will demand first of all from the room where it is installed if there is no external input as more and more stoves have.
This is often a recurring cause of smoke leakage in many facilities. At the beginning there is sufficient oxygen supply and the chimney pulls well, until the oxygen nivel is poor and directly affects combustion.
If you detect that the combustion nivel has dropped a lot when you have the doors closed, you should open a door to inject air, and it will surely improve the combustion process, fanning the flames, improving combustion and reducing the amount of smoke generated.
Ideally, in order not to cause condensation inside the tubes, they should have double walls, with thermal insulation. This avoids many problems over time, since the increase in humidity can cause the creation of creosote, which adheres to the walls and gradually reduces the smoke exit section, preventing the correct exit, and therefore, generating smoke inside the room.
The final cap is also very important, it must prevent the entry of air, water, animals that obstruct the smoke outlet, and that cause as a consequence, a decrease in the smoke outlet section.
The height of the smoke outlet with respect to the outdoor areas is also important because it could create unfavourable pressure conditions that also prevent the correct smoke outlet. In this way, there are many installations in interior courtyards whose ambient pressure does not allow a correct escape of the fumes and causes a continuous plastering smoke.
