May 21, 2019
Pellet burning heating is offered in a range of alternatives, tailored to the most specialized needs of each consumer, with always the goal of reducing costs and saving money.
What is pellet
The pellet consists of small aggregates of pure wood residues, the production process of which consists of 5 steps. Originally the raw material is collected and stored in suitable areas, paying particular attention to moisture.
Drying is followed where it is reduced to the minimum moisture content. After drying, the raw material is chopped and milled and then compressed by special presses to get the characteristic cylindrical shape. Finally, the pellet is cooled and sieved to ensure the correct size and stored in a safe place, again giving special importance to the humidity of the space.
In the above procedure, what basic role is played by the raw material used. In particular clean wood, without impurities, should be used. At the same time no chemical is to be used during production, and any change in production conditions (for example insufficient drying) results in inferior product quality with lower energy efficiency.
Depending on the raw material used the pellets can be divided into the following categories:
– wood pellets made of 100% wood,
– pellets made from energy plants,
– pellets made from agricultural residues such as wheat, artichoke and corn
What is more important is the type of wood from which the pellet is composed, and how much each of them is involved in the final mix are directly related to a number of parameters such as their thermal performance, combustion quality and the cost of buying .
Wood pellets are the ones with the best combustion efficiency.
It should be noted that the percentage of solid residues of combustion is also decisive for the pellet burner, which decisively contributes to the percentage of solid residues, with its degree of combustion efficiency.
There are specific EU guidelines for the acceptable solid residue level.
Certifications for the pellet
In order to ensure the market for good quality pellets, some standards have emerged, both by the European Union and by individual countries, which guarantee the consumer good and stable fuel quality. Particularly in the case of home consumers, it is necessary to use only certified quality pellets, both for economic and environmental reasons.
The new European Standard (EN14961-2), which has been in force since 2011, introduces the ENplus certification, which is particularly demanding in terms of wood pellet production quality and the process in which it is marketed.
Basic advantages for a consumer to choose ENplus wood pellet quality is the certainty that he is procuring a certified quality product, resulting in efficient, economical and ecological combustion in his boiler or stove.
According to this standard pellets can be certified for their classification in two categories of quality, A1 and A2. Category A1 is the highest quality pellet wood that can be used in domestic boilers and pellet stoves. Category A2 is used in larger power plants, and is also a fuel with higher ash content (ash). In addition, the quality class B pellet is not included in the ENplus certification and is used in industrial applications.
Thus for domestic heating in private households, it is recommended to use only ENplus wood pellets class A1. In addition for boilers of high power (> 100kW), class A2 pellets can also be used. The main difference between A1 and A2 category is focused on ash content and ash melting behavior. Also, the range of basic raw materials for the production of these pellets is greater than for the ENplus A1 class. The following table summarizes the qualities of the various wood pellet categories according to EN 14961-2.
More information on the ENplus standard and for the certified pellet manufacturers can be found at http://www.enplus-pellets.eu/.
The TuV HELLAS inspection and certification body grants ENplus pellet certification as an approved body by the European pellet Council, aiming to ensure the quality of the products for the protection of the environment, the health of the citizens and the coverage of needs of the consumers.
Comparison of certifications
It is worth noting, however, that some brand of pellet may not have the Enplus certification, but it will have other certifications.
This does not mean that it is of inferior quality. This is due to the fact that countries where pellets have been used as a fuel have introduced various standards to ensure their quality.
Products bearing this certification are of equivalent quality to those certified with ENplus.
The most common certifications are DIN-51731 and DIN plus from Germany, as well as the Austrian ONORM M1735. The table below shows the specifications of each certification as compared to ENplus certification.
Cost of use The efficiency of combustion in pellet boilers can reach up to 90% and 1Kg of good quality pellet yields about 4000kCal (as opposed to 1lt of oil yielding approximately 8500kCal). The cost for 1 ton pellet is approximately 350 €.
For heating a 100 square metres house, 2.6 tons of pellets will cost around € 850-900 a year compared to the fuel required by oil heating (1300lt x 1.35 € / ltr).
The ratio between the two types of fuel mentioned above is: 1 liter of heating oil = 2,14 kg of pellets. This means that in order to get the energy that a liter of oil gives me when I burn it, I need to consume 2.14 kg of pellets.
Certifications for pellet burners
In addition to the suitability of solid fuels, combustion heaters (boilers, pellet stoves, fireplaces, etc.) must be CE marked according to EN 14785, which means they have been tested according to European standards and are suitable for this use but and efficient.
Stoves can have several certifications. The most common, depending on the characteristics of the stove are the following:
CE marking according to EN 14785
The stoves bearing the CE marking according to EN 14785 meet the European Union Standard 14785, which relates to the design, construction, safety, performance and control of engine-powered stoves up to 50 kW . These stoves may have an internal or external hopper for storing pellets and always operate with the door closed.
CE marking according to EN 13240
Stoves with the CE marking according to EN 13240 meet the European Union’s 13240 standard. This standard relates to specifications relating to the design, manufacture, safety, performance and control of heated appliances manually fired by solid fuels. This standard does not cover appliances equipped with combustion assist fans.