Any heating system powered by wood, pellets or wood chips need one flue, whose correct installation becomes an indispensable prerequisite for the proper functioning of the heating system.
Through the flue the combustion fumes escape, which exploits the upward movement of the hot fumes inside the chimney, known as the "draft".
The secret of a good draft is represented by a set of technical and plant engineering measures: the outgoing fumes, being lighter, tend to rise upwards by exploiting the pressure difference with the outside air.
Correct chimney installation, useful information
In order for the flue to work properly, some factors must be considered
- The walls of the flue must not have any minimal roughness; this would cause friction in the fumes, decreasing the draft efficiency
- Steel is certainly the best material, so it is preferable to building materials such as brick
- Another important aspect is given by the dimensions: a small diameter flue, keeping the temperature of the fumes high, increases the speed of escape, while a large chimney slows it down.
- It is also important to avoid that the chimney has horizontal sections: this would slow down the draft and favor fouling
- A high temperature of the fumes in the chimney determines a good draft and also avoids condensation and fouling problems
- It is necessary to prepare an external air intake in the same room where the appliance is installed in order to ensure a constant exchange of oxygen, essential for good combustion.
A good flue must therefore ensure the right draft: if it were to be poor draft it would slow down the combustion, decreasing its efficiency, if it were to be excessive, it would result in an increase in fuel consumption, without bringing benefits in terms of greater heat.
Correct flue installation for pellet stoves
The proper functioning of a pellet stove is given by the correct installation of its flue. To make the most of the heat, the stove should be positioned in the center of the rooms, but you must always take into account the positioning of the flue gas exhaust and therefore the position may not always be the optimal one. Creating a flue from scratch for pellet stoves is not very complicated: to ensure correct operation, you need to have few and short horizontal sections and there must not be more than three direction channels, including the connection to the flue.
Prefer insulated pipes for the external part of the flue, to prevent condensation from forming inside the flue: it could end up in the combustion chamber and cause poor combustion of the pellets.
For further information, we recommend reading the article "Chimney, how it works"