It’s cold, wet and uncomfortable outside and inside a cozy log fire patterns. At this performance, you feel comfortable and think of warmth and coziness and more and more people put them directly into action by putting a stove in the living room. The so-called Swedish stoves are easy to install and can also be installed in rental apartments if a connection to the chimney is given.
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How does a stove work?
For a stove to work, it requires a so-called chimney effect. As a chimney effect in physics, an air movement is called, which leads to a vertical air flow. Through this chimney effect, the exhaust gases from the stove are transported through the chimney outside and at the same time creates a negative pressure in the chimney through which new air is sucked in order to maintain the combustion process.
The stove is supplied to this in three different ways air:
- Primary air supply
- Secondary air supply
- Tertiary air supply
The primary air is supplied to the firebox from below via the grate. She is responsible for the combustion of fuels. The secondary air is supplied to the combustion chamber from above. It serves to ensure the afterburning of the hot gases and is also an important part of the washer. The tertiary air is supplied to the combustion chamber from the rear. Their task is to optimize combustion even further and to ensure the effective afterburning of remaining exhaust gases.
The chimney effect, which is primarily due to the fact that warm air is lighter than cold air and therefore rises due to its lower density, maintains the system of air exhaust through the chimney and fresh air intake during the operation of the stove. This principle is also referred to as the train’s chimney.
The heating capacity of a stove is caused by two different effects. Through the combustion process, the body of the stove heats up and it radiates radiant heat to the room. The second effect that leads to a warming of the environment is the convection heat. Room air flows through a chamber system between the body and the cladding of the stove. The air is heated and released back to the room and new cooler air flows after. The cladding of the stove can, for example, consist of soapstone, steel or cast iron, granite or ceramic.
Various types of stoves
Fireplaces and stoves are available in many different versions. In this guide on gmomf.org, we deal with the stove with the lens, which is also known as the Swedish stove and fired mainly with wood, sometimes with coal. For the sake of completeness, however, let’s take a look at the many other variations of fireplaces and stoves to give you a comprehensive overview.
- Fireplace The classic fireplace is surely the open fireplace. It differs from the stove in particular in that it is firmly installed in the room. An open fireplace is usually built directly in the room and he has in most cases no glass, which separates the firebox. As a rule, wood logs are used as fuel for the open fireplace.
- Gas fireplace A gas fireplace is a heating chimney connected to a gas connection or powered by propane gas from gas cylinders. Gas fires have good heating performance and are considered environmentally friendly.
- Electric fireplace The electric fireplace is not a fireplace in the classical sense. It is powered by electricity and it merely creates the illusion of an open fire.
- Bioethanol fireplace bioethanol fireplaces need no connection and no chimney. Bioethanol burns without smoke, toxins or fumes so that the fireplaces, which are available in many different designs, can be placed freely in the room. Bioethanol fireplaces can heat up a room very quickly, but the heat output is only very short-term.
While these chimney types differ mainly due to their fuel, it is necessary to differentiate between the following variants:
- Water-bearing fireplace
- storage fireplace
Heating stoves are all chimney systems that are suitable for heating rooms.
Storage fireplaces also have storage areas, for example, made of ceramic, in which the heat of the fireplace is sustainably stored. Thus, the fireplace still gives off heat even when no more burning takes place.
Water-bearing chimneys can be connected with a pipe system to the circuit of the central heating and can support the entire central heating and hot water preparation in addition to their direct heat output.
The stove is characterized by the fact that unlike the open fireplace it has a closed combustion chamber. A large window in the door, however, allows in most stoves a look into the combustion chamber, so you can enjoy the sight of the roaring fire like an open fireplace. Due to the closed combustion chamber, however, the stove has a higher efficiency compared to the open fireplace. Wood chips and lignite briquettes are suitable as fuels, with some stoves also being suitable for burning coal. The stove is usually not firmly installed and can, if a suitable chimney is present, easily retrofitted.
The term endurance or continuous kiln has nothing to do with whether a stove is constantly burning or can. In connection with the burning time, the term continuous operation is decisive, because it indicates a possible operation of the stove 24 hours around the clock. The term endurance fire, in contrast, is in contrast to the time fire and comes from the test specifications that are relevant for coal stoves. A long-life kiln is, therefore, a wood-burning stove with a so-called coal license, which is primarily suitable for the combustion of coal and less for the combustion of wood. The long-term kiln must be able to hold the embers at a given nominal heat output for a period of at least four hours. This period during which the coal embers are held is called endurance fire. In contrast, there is the time-burning stove, which is primarily suitable for the burning of wood and does not have a coal license. The period over which he has to keep the embers at a given nominal heat is only 45 minutes.
Fuels for the stove
The fuel for a fireplace can be very different and depending on the type of fireplace, for example, gas or bioethanol in question. However, in a wood-burning stove, only wood or coal are burned and many stoves are only allowed for the burning of wood. The wood to be burned is usually firewood. Firewood is used to refer to trunk wood sections that have been split longitudinally with an ax or a splitter. A log usually has a length of 33 cm and most stoves are aligned with the size of their firebox to this extent. Some of the so-called time burners, which are designed for the burning of firewood, can additionally be fired with lignite briquettes to keep the embers better. The predominant burning of coal, however, requires a specially designed long-term kiln, which has a corresponding coal license. It is equipped with another combustion chamber in which there is a chute for the burning coal. This so-called nest ensures that the coal burns optimally and the embers can be kept in accordance with the requirements of a long-term kiln. Once the coal is burned out in the nest, new coal slips from above and so there is always a glowing nest at the bottom of the cow. that the coal can burn off optimally and the embers can be kept in accordance with the requirements of a long-term kiln. Once the coal is burned out in the nest, new coal slips from above and so there is always a glowing nest at the bottom of the cow. that the coal can burn off optimally and the embers can be kept in accordance with the requirements of a long-term kiln. Once the coal is burned out in the nest, new coal slips from above and so there is always a glowing nest at the bottom of the cow.
Heating power and space heating
The heating capacity and the space heating capacity of a stove play a big, if not the most important role in the selection of the appropriate stove. So the rooms should be pleasantly heated by the stove, but they should not be overheated. Therefore, before purchasing a stove, it is important to first define the future purpose of the stove. If the stove is primarily used to create a cozy atmosphere on cold winter evenings and should, therefore, be used only occasionally, a different heating capacity must be selected than if the stove is to be used to support the central heating or even replace. In the latter case, you should consider buying a water-bearing fireplace.
Decisive for determining the heat outputs are the square footage of the room to be heated and the insulation of the property. However, the insulation of the building can be individually very different and usually, therefore, the age of the building is expected. For refurbished and renovated buildings, the time of the refurbishment measure applies. The required heating power in kilowatts can be roughly calculated with these two factors according to the following formula:
- For buildings built before 1978, about 120 to 180 W / m² are used
- For buildings built after 1978, about 80 W / m² are used
- For buildings built after 1995, about 60 W / m² are used
- For new buildings that are less than ten years old, about 45 W / m² are used
After determining the year of construction of the property, multiply the corresponding value by the size of the room in square meters. The subsequent result is then multiplied once again by a factor of 1.5 to compensate for heat losses.
Example calculation for a 35 m² room in a new building from 2012:
35 (m²) x 45 (W / m²) = 1575 W = 1.5 kW
1.5 kW x 1.5 = 2.25 kW
For a room of the same size in an unrefurbished building built in 1982, according to this rule of thumb, the required heating power is 4.2 kW. Using this formula, you have now calculated a rough guideline, which you can use to orient yourself when buying a stove. In practice, however, other aspects such as the construction and the local climate must be considered, but the value serves as a guide and helps you, above all, to prevent overheating of the rooms by a stove with too high heating power.
The smaller the room that is to be heated by the stove, the harder it is sometimes to find the right stove. Most woodburning stoves have a seating capacity of 5 to 7 kW and are therefore already oversized for many small rooms. However, you can operate the stove, inter alia, by the moderate supply of firewood with a lower heat output, so as not to sit in a completely overheated apartment.
Another important value in terms of heating power is efficiency. It is expressed as a percentage and denotes the ratio between the energy used and the useful energy. It is therefore quantified how much of the energy used is actually available as heat. Using a value of 100%, this would mean that all the energy supplied to the stove in the form of wood or coal is converted into heat. However, such a value can never be achieved because there are always losses due to exhaust fumes.
Legal regulations around the stove
Environmental protection plays a major role in the approval of wood-burning stoves. Decisive factors here are, above all, the exhaust gases and the amounts of particulate matter and carbon monoxide which are expelled with the exhaust gases. This emission is regulated in the Federal Immission Control Ordinance BImSchV. The regulation lays down the limit values for carbon monoxide and particulate matter emissions and all newly constructed chimneys and stoves must comply with the prescribed limit values.
The Federal Immission Control Ordinance entered into force in March 2010 with the first stage and since then, chimneys and stoves must prove a manufacturer’s certificate confirming compliance with the limit values. On 1 January 2015, the second stage of the BImSchV came into effect. However, stoves that already meet the requirements of the first stage are not affected by the second stage and may continue to operate indefinitely. For older wood-burning stoves, on the other hand, a phased plan has been in force since 2010, according to which, depending on their age, the stoves must be retrofitted or taken out of operation by a certain deadline.
You must pay attention to this when operating a fireplace
A stove works with an open flame and it can get very hot during operation. Temperatures of 1,000 ° C and more can be reached in the combustion chamber in the combustion chamber and also burning logs bring it to temperatures of 500 ° to 750 ° C. For safety, it is therefore very important that appropriate distances are respected to the fireplace, so nothing Can catch fire. The minimum distances that must be maintained to the front, to the sides, and to the rear wall are usually 80 cm in the front radiation area and 20 to 25 cm to the side walls and rear wall. The exact numbers for your stove can be found in the manual. Within this radius, there must be no flammable or heat-sensitive materials such as furniture or curtains.
Furthermore, the stove gives off heat down. If the floor is equipped with a combustible covering such as wood, carpet or laminate, the stove must, therefore, stand on a special base plate made of a non-combustible material. This floor plate may, for example, consist of sheet steel, safety glass or tiles and it must be on the sides in at least 30 cm larger than the base of the stove and front at least 50 cm beyond the footprint. This protects the soil from ashes and flying sparks.
Equipment of the stove
Modern stoves have a range of features that make the operation of the stove easier or more complete.
Rinsing Most modern woodburning stoves have a window washer. Specially conducted air streams prevent soot and other deposits from settling on the inside of the viewing window. So you always have a nice view of the flames and the disc does not need to be cleaned from the inside.
- Tempered door handle
A tempered door handle is also part of the equipment of many stoves. It makes it possible to open the door of the stove during operation without a chimney glove, for example, refill wood.
- Wood compartment
Many woodburning stoves have a practical wooden compartment at the bottom. Their logs can be stacked cleanly and practically and there is always wood ready for refueling. A wooden compartment also saves space in a small room compared to a wooden basket.
- Heat Tray
Above the combustion chamber, some stoves have a heated shelf. It can be open or with a glass door and is suitable for keeping tea warm, for example
Other stoves have a baking compartment. This tray can be used as an oven and food can be prepared in it. So the heat of the stove is also used for cooking.
Accessories for the stove
In the trade, there are also some accessories for stoves to buy. These include on the one hand indispensable parts such as flue pipes or nozzles, which are necessary for the installation of the stove. Furthermore, various heat protection plates or spark grids are commercially available. In addition, there are many accessories around the stove such as firewood baskets, fireplace cutlery, bellows and more.