Nice-to-know information gathered in one place
Irrespective of whether you are a new or seasoned user of wood-burning stoves, there are lots of things that can be nice to know both before and after your purchase. We have gathered all this information in one place so that it is quick and easy for you to immerse yourself in the topics you find interesting. Click your way through the topics underneath.
How do you choose the stove that's right for you?
TermaTech’s stoves are convection stoves. Their basic structure is produced in 3-5 mm thick quality steel. Cast-iron components are always used in TermaTech stoves where the temperature is highest. Examples of this are the bottom of the combustion chamber, the internal frame of the door and other parts.
The most important thing is that the stove is built to last for many years and you are assured of this when you choose a TermaTech wood-burning stove.
STOVE TYPE – EMISSION OF HEAT
Roughly speaking, there are main three types of stove: Radiation stoves, convection stoves and storage heating stoves.
The drawback with radiation stoves is that the surface of the stove gets very hot and the area immediately surrounding it gets hot rapidly. Very few of the stoves produced today are radiation stoves.
Convection stoves, which are the most common type of stove on the market today, have an external jacket, which is open at the top and at the bottom. The air between the actual stove and the outer jacket is heated up and the warm air is sent out of the stove and the air circulated around the room. The air is distributed better than it is with radiation stoves.
Storage heating stoves accumulate the heat from the wood-burning stove in order to emit the heat over a longer period later on.
AIR WASH SYSTEM
Warmed air is blown down the inside of the glass and counteracts and minimises the formation of soot on the glass. All TermaTech stoves are equipped with an air wash system.
CLEANING
Generally speaking, wood-burning stoves do not require much cleaning. However, you must check all sealing bands and moving parts before the start of the heating season and rinse and clean the inside of the stove once the heating season is over. The ash is emptied as required, but be careful – if there are smouldering embers in the ash there is a risk of smoke or fire damage in your waste receptacle etc.
The glass is cleaned either with TermaTech’s special glass cleaner of with a little bit of water on a piece of kitchen roll which is then dipped in the ash and used to scrub the inside of the glass.
The surface of the stove is cleaned using a dry cloth, a soft, dry brush or a tightly scrunched up moist cloth. Never use water or cleaning agents on the painted surfaces.
TOP OR REAR OUTLET
The rear outlet solution requires a good passage of air from the chimney since this solution creates more resistance to the path of the smoke. The smoke should preferably follow its natural trajectory – upwards.
SOAPSTONE
Soapstone is a natural product which has an outstanding ability to retain heat. This stone is often used for storage heating stoves where a more even distribution of heat is desired. Every single soapstone has millions of years of history behind it and has a unique appearance and structure.
CHIMNEY DRAUGHT
Even the very best wood-burning stove cannot function properly if it isn’t connected to a good chimney. The chimney is “motor” or “lungs” of the stove, if you like. A poorly insulated chimney or chimney that is too low will often result in a bad draught.
A bad draught results in poor combustion and smoke spillage when the door is opened.
VERMICULITE
An insulation material that affects the temperature in the combustion chamber and, consequently, results in a higher temperature and cleaner combustion.
EXTERNAL COMBUSTION AIR DUCTS
A connection whereby the air required in order for the stove to function correctly is supplied externally. An external air supply to the stove’s combustion air duct is often necessary in new houses because the houses are extremely airtight. In airtight houses, a vacuum can easily be created which means that the wood-burning stove is not able to function correctly.
First of all, you must consider your needs thoroughly before choosing a wood-burning stove. Therefore, think about:
The placement of the stove, the type of building, the area that is to be heated, the style and design.
THE QUALITY
It isn’t only the design that differentiates one wood-burning stove from another.
The combustion technique and the materials used do too.
Therefore, robust materials, solid hinges, the construction of the door and a good insulating material are just a few of the things you should be aware of.
THE HEAT EFFECT – HEATING FOR A SMALL AREA OR A LARGE AREA
The stove should have the desired effect in relation to the area you wish to heat.
Always refer to the specified operating range and the manufacturer’s instructions. Remember that a small stove with a small combustion chamber burns cleanly with a modest output but can also easily give out a lot of heat and still burn cleanly.
If the stove is too big, there is a risk that you will have to turn the stove down too much because of the heat with the result that it doesn’t burn cleanly.
Thus, the conclusion is: It is better to have a small stove that is allowed to “work” rather than a large stove that doesn’t function properly and harms the environment.
The effect is stated in kilowatts (kW). As a rule, a convection wood-burning stove heats an area of 10-20 m2 per kW, depending on the level of insulation in the house, height to the ceiling etc.
TermaTech supplies stoves with an output between 3-10 kW.
ENVIRONMENTAL LABELS – NORWEGIAN STANDARD, AUSTRIAN STANDARD, HETAS, DEFRA, DIN PLUS etc..
When you choose a new wood-burning stove, it is important to check whether the stove has been approved and certified. All new stoves on the market must, as a minimum, be tested in accordance with the current European CE norm/standard. This guarantees that the wood-burning stove burns safely, cleanly, efficiently and in an environmentally friendly way.
TermaTech’s stoves have been tested and meet the most stringent European standards with regard to particle measurement etc.
The new German standard, called BImSchV 1+2, not only helps ensure efficient and clean-burning stoves, but also ensures that old wood-burning stoves are replaced. BImSchV, which stands for ”Bundes Immisions Schutz Verordnung (the Federal Emission Control Act)” is split into two stages. Both Stage 1 and Stage 2 approved stoves may be mounted and can be used in the future since they meet all the requirements. All old wood-burning stoves must be replaced no later than 2024.
All of TermaTech’s stoves already meet the Stage 2 requirements, which means that they will not have to be replaced at any point. This is yet another guarantee that a TermaTech wood-burning stove is a wise and environmentally-friendly choice.
The Austrian standard – also called §15, sets even stricter requirements for hydrocarbon emissions and efficiency than Svanemærket, the Nordic Eco Label, does.
PLATE IRON VERSUS CAST IRON
It makes no real difference whether you choose a cast iron stove or a plate iron stove. The biggest difference lies in the appearance and expression – however, there is one place in the stove where cast iron can make a difference.
Cast iron is better able to withstand extremely high temperatures. Therefore, it is a good idea to choose a wood-burning stove in which the parts subjected to the highest temperatures, for example, the bottom of the combustion chamber and the interior of the door, are made from cast iron. The rest of the stove can be made from plate iron since the temperature of these parts never gets so high that they strain or break down the steel.
Plate iron stoves/steel stoves often have an advantage over the conventional cast-iron stoves, and that is convection heat transfer. Convection heat transfer is best achieved in a plate-iron stove where there is space between the interior of the stove and the outer jacket. The heated convection air rises upwards and is distributed significantly quicker into the room than the radiation heat from an old-fashioned cast-iron stove.
TermaTech’s stoves are convection stoves. Their basic structure is produced in 3-5 mm thick quality steel. Cast-iron components are always used in TermaTech stoves where the temperature is highest. Examples of this are the bottom of the combustion chamber, the internal frame of the door and other parts.
The most important thing is that the stove is built to last for many years and you are assured of this when you choose a TermaTech wood-burning stove.
STOVE TYPE – EMISSION OF HEAT
Roughly speaking, there are main three types of stove: Radiation stoves, convection stoves and storage heating stoves.
The drawback with radiation stoves is that the surface of the stove gets very hot and the area immediately surrounding it gets hot rapidly. Very few of the stoves produced today are radiation stoves.
Convection stoves, which are the most common type of stove on the market today, have an external jacket, which is open at the top and at the bottom. The air between the actual stove and the outer jacket is heated up and the warm air is sent out of the stove and the air circulated around the room. The air is distributed better than it is with radiation stoves.
Storage heating stoves accumulate the heat from the wood-burning stove in order to emit the heat over a longer period later on.
AIR WASH SYSTEM
Warmed air is blown down the inside of the glass and counteracts and minimises the formation of soot on the glass. All TermaTech stoves are equipped with an air wash system.
CLEANING
Generally speaking, wood-burning stoves do not require much cleaning. However, you must check all sealing bands and moving parts before the start of the heating season and rinse and clean the inside of the stove once the heating season is over. The ash is emptied as required, but be careful – if there are smouldering embers in the ash there is a risk of smoke or fire damage in your waste receptacle etc.
The glass is cleaned either with TermaTech’s special glass cleaner of with a little bit of water on a piece of kitchen roll which is then dipped in the ash and used to scrub the inside of the glass.
The surface of the stove is cleaned using a dry cloth, a soft, dry brush or a tightly scrunched up moist cloth. Never use water or cleaning agents on the painted surfaces.
TOP OR REAR OUTLET
The rear outlet solution requires a good passage of air from the chimney since this solution creates more resistance to the path of the smoke. The smoke should preferably follow its natural trajectory – upwards.
SOAPSTONE
Soapstone is a natural product which has an outstanding ability to retain heat. This stone is often used for storage heating stoves where a more even distribution of heat is desired. Every single soapstone has millions of years of history behind it and has a unique appearance and structure.
CHIMNEY DRAUGHT
Even the very best wood-burning stove cannot function properly if it isn’t connected to a good chimney. The chimney is “motor” or “lungs” of the stove, if you like. A poorly insulated chimney or chimney that is too low will often result in a bad draught.
A bad draught results in poor combustion and smoke spillage when the door is opened.
VERMICULITE
An insulation material that affects the temperature in the combustion chamber and, consequently, results in a higher temperature and cleaner combustion.
EXTERNAL COMBUSTION AIR DUCTS
A connection whereby the air required in order for the stove to function correctly is supplied externally. An external air supply to the stove’s combustion air duct is often necessary in new houses because the houses are extremely airtight. In airtight houses, a vacuum can easily be created which means that the wood-burning stove is not able to function correctly.
Make sure that you do it correctly.
The firing-up stage is absolutely crucial to getting a well-functioning wood-burning stove since proper firing-up quickly creates an optimal combustion temperature and a good chimney draught.
HOW TO FIRE UP PROPERLY!
1: Place 2 large pieces of fuel (5-8 cm thick), with the bark facing downwards, at the bottom of the combustion chamber.
2: On top, build a little tower of 12-14 kindling sticks with an adequate supply of air between them.
3: Place a couple of briquettes/pellet bags between the uppermost layers.
4: Ignite the briquettes/pellet bags so that the wood burns from the top down. Leave the door slightly ajar.
5: After approximately 10 minutes, or when you can easily feel the heat at a distance of 15-20 cm from the glass, close the stove door.
6: Once the flames have died down to embers, it is time to add new wood. NEVER OPEN THE DOOR while there is flames! If there are flames, there are gases – if there are gases, there is smoke – and if there is smoke, it will come out when the door is opened!
Carefully, open the stove door 1-2 cm, and after approximately 5 seconds it can be opened fully. You can now put 2-3 pieces of dry wood on the stove – it may help to stoke up the embers before you put the new wood on top of them.
ALWAYS REMEMBER:
– Light the fire at the top, that way you can save up to 80% of the particle emissions being emitted into the environment during the firing-up phase.
– Always use one or more firing-up blocks and lots of dry firewood that has been broken up into small pieces.
BASIC RULES FOR CORRECT FIRING
1: Use wood that is clean and dry with a maximum of 18-20% moisture. A moisture meter is relatively inexpensive and can specify the water content. See TermaTech’s moisture meter at your dealer ‘s showroom.
Wet wood does not burn well, gives off a lot of smoke and creates more pollution. Never fire up with waste materials – waste materials may contain carcinogenic dioxins and will render the warranty void. Never fire up with carbon or carbon products.
Never fire up with pressure-impregnated wood– even small amounts contain acids that will destroy the stove and chimney.
2: Make sure there is an abundant supply of air – An insufficient air supply can result in the smoke containing harmful particles. It can result in the formation of soot on the window, in the stove’s interior and in the chimney. It also harms the environment.
3: Fire up a little at a time – The fire has to take hold in the fuel so that the temperature gets high quickly. Large pieces of wood have a lot of mass and a small surface, which means that it takes too long to get the core temperature up. Consequently, the fuel will simply smoulder instead of burning.
The firewood should not measure more than 30 cm (In very wide stoves it can be longer) and should not be thicker than a man’s forearm. Using 2-3 pieces of wood every time you fire up the fire will give the best combustion.
4: NEVER try to “fire over”. Wood must have air in order to burn correctly. Limiting the air supply will result in the wood emitting gases but these will not ignite. Instead, they will pollute the environment, the stove and the chimney.
5: Go outside and check – The smoke from the chimney should be almost invisible – If there is too much smoke and it smells nasty, you are probably doing something wrong.
Keep warm while caring for the environment.
The amount of CO2 emitted from a piece of firewood that is rotting in the forest roughly equates to the amount of CO2 that is emitted from the same piece of wood when it is burnt. When the forest is fully grown, the trees take up the same amount of CO2 that they emit when they are rotting or being burnt. Therefore, using wood for heat is CO2 neutral and, as opposed to fuelling a fire with oil, gas etc. does not contribute to global warming but instead becomes part of a natural cycle.
CHECKING DRYNESS
You can buy a moisture meter for measuring exactly the water content which, as mentioned before, must be no more than 20%. Alternatively, you can try one of the old-fashioned methods:
Strike the pieces of firewood against one another. Dry firewood emits a sharp sound. Wet firewood emits a dull sound.
Spit on one end of the firewood, or dip it in soapy water. Blow hard on one end. If the air gets through and the spittle bubbles up, then the firewood is dry.
Let it depend on a test: If the firewood burns easily with a clear yellow flame but generates a lot of smoke then it is not dry enough.
ALL WOOD SPECIES MAKE GOOD FUEL
Generally speaking, there is no species of wood that is better than another when you use a wood-burning stove for heating. Light wood species are both easier to chop and to ignite and are therefore suitable when you fire up. On the other hand, they burn more quickly than the heavy wood species and generate somewhat less heat. Therefore, it makes good sense to combine the light and heavy wood species if you want to fire your stove economically.
THE SPECIES OF WOOD AS FIREWOOD
All species of wood produce an equal amount of heat per kilogram of firewood. However, not all wood species weigh the same. (See the table below)
The calorific value in 1 kg of dry wood is 19 megajoules. That is equivalent to roughly a ½ litre of oil. However, in practice, there will always be a little water in the firewood and the efficiency of a wood-burning stove is not as high as an oil-fired stove. As a rule of thumb, with a cubic metre of fuel it is possible to save around 150-200 litres of oil.
Characteristics of wood types
The basic density can vary 10-20% on either side. Cleavability is indicated on a scale where 1 = very easy to chop, 2 = easy to chop, 3 = difficult to chop, 4 = very difficult to chop.
DRYING FIREWOOD
You cannot always count on being able to buy all the dry firewood you will need for the winter in the autumn. Buy it in the previous spring at the latest and follow this drying process:
1: The tree is felled before 1 April.
2: Cut and chop the firewood as quickly as possible. By 1 May at the very latest. Chopping the wood helps it to dry out more quickly because water can only evaporate slowly through the bark of the tree.
3: Store the firewood under a porch roof over the summer. In cases of emergency, a tarpaulin can be used. Check the moisture level again before you use it.
4: Preferably move the firewood indoors a week before it is to be used. Thump the pieces of firewood against something hard so that beetles and craneflies are not taken inside along with the wood. Your family and pets will appreciate it. Once in the living room, the water content of the firewood can be brought below the recommended 20%.
Get to know your wood-burning stove from top to bottom.
The basic component of any wood-burning stove is the combustion chamber. In order to achieve a high combustion temperature it is necessary to insulate the combustion chamber. Normally, Vermiculite is used. This is a light material which, among other things, contains rock material/moler earth. Sometimes fire-resistant rock is used instead.
ANY COMBUSTION REQUIRES OXYGEN, THIS CAN BE PROVIDED IN A NUMBER OF WAYS:
The primary air at the bottom of the combustion chamber.
The secondary air or scavenge air over the glass/door – also called the air wash system. The air for the air wash system should preferably be heated.
Tertiary air, or mixed air, which is supplied through the holes at the rear of the stove, just above the firewood. The tertiary air should preferably be heated.
The primary air makes it easier to ignite the firewood. However, it is important that the primary air supply is closed off once the flames have taken hold.
The secondary air, or air wash system air has a basic function besides supplying the air for combustion. The air flows down over the glass and prevents the formation of condensation and soot particles on it. This reduces the formation of soot considerably.
The tertiary air creates turbulence in the combustion chamber and helps the air and gasses to mix better whereby more complete combustion is achieved.
SMOKE BAFFLES
Vermiculite of fire-resistant rock has an insulating effect but, of course, the heat from the flames needs to be transformed into heat in the room. Therefore, the smoke in the combustion chamber is converted via one or more smoke baffle plates. The flue gases come into contact with the stove’s steel components and these are heated up. The heat goes through the steel plates on the outside surface of the combustion chamber and the heat is transferred via the convection of the stove into the room. In addition, some of the heat on the glass is released into the room as radiation heat.
Via this baffle system, the temperature is reduced from 700-750°C, to an average of around 250°C before the smoke goes out into the chimney.
EFFICIENCY
A stove’s ability to burn off flue gases and its ability to cool them down and transmit the heat to the surroundings is an expression of the stove’s efficiency.
A modern stove has an efficiency level of around 80%.
An open log fire has an efficiency level of around 20%.
A fire has an efficiency level of around 10%.
The easiest way to do this is with a vacuum cleaner with a soft brush attachment – avoid scratching the stove. Alternatively, you can use a dry or tightly scrunched up cloth or a soft brush. Never use a wet cloth or similar, since water and cleaning agents can attack the lacquer and lead to the formation of rust. The paint used on the stove is not corrosion-resistant.
CLEANING THE GLASS
Clean the glass with a dry cloth as required. If there is still soot residue on the glass this can be removed in one of the following ways (the stove must be cold):
1: With a special liquid glass cleaner.
2: With a piece of moist kitchen roll dipped in the uppermost white ash and used to scrub the glass. Lastly, dry it off with a piece of dry paper. Make sure that there are no impurities in the ash which can scratch the glass.
INSULATION – VERMICULITE
Over time, the combustion chamber’s efficient but porous insulation can get worn and damaged. If the baffle plate cracks, it may lead to the secondary air being distributed incorrectly in the combustion chamber and it should therefore be replaced. Should the side panels crack, this will have no impact on the efficiency of the stove. Side panels and baffles should be replaced when they wear away to around half of their original thickness.
SEALING BANDS
The sealing band should be replaced as and when required, i.e. when it looks worn out or when you suspect that the stove is no longer air-tight. It may be necessary to do this once a year, or perhaps every five years, depending on how much the stove is used.
Tips: You can check the air-tightness by jamming a piece of paper between the door and the stove. If the paper can be pulled out easily (and without any resistance), this may indicate that the door on the stove is not completely air-tight.
LUBRICATING THE HINGES AND CLOSING MECHANISMS
Hinges and closing mechanisms on the door should be lubricated once a year. Use a heat-resistant lubricant.
PAINTING THE STOVE
Over time, the paint can become worn, or the stove can get scratched accidentally. It is relatively easy to remedy this damage by using Senotherm Spray (it can be purchased from the dealer ). This spray is the original heat-resistant lacquer used by the manufacturer to paint the stove. Be aware that the stove may smell again when the paint hardens and you fire up for the first time after you have applied it.
SUMMARY
The wood-burning stove should undergo a thorough maintenance check once a year.
This check should include:
– Thorough cleaning of the wood-burning stove
– Lubrication of the hinges with copper grease
– Checking and, if necessary, replacement of the sealing bands
– Tightening and, if necessary, adjustment of the handles/door
– Checking and, if necessary, replacement of the heat-insulating material
– If necessary, this check can be carried out by a dealer
Use only original spare parts.
Occasionally, heating by means of a wood-burning stove can be problematic.
Many of the problems can be avoided by knowing about the following problems beforehand:
INSUFFICIENT CHIMNEY DRAUGHT
In order for the stove to function the glass must be kept clean and sufficient oxygen supplied for combustion. This requires sufficient chimney draught. Insufficient chimney draught can be a result of the chimney being too low or inadequate.
A NEW STOVE DOESN’T FUNCTION
New stoves have a much higher level of efficiency that old stoves. This greater efficiency is achieved by reducing the temperature of the flue gas before it leaves the stove. This means that the temperatures in the chimney and, consequently, the draught are lower than they were previously.
IMPACT OF EXTERNAL WINDS
The height of the chimney should be suited to the height of the roof. External circumstances can be the cause of a poor draught in the chimney.
1: The chimney is too low in relation to the roof.
2: Leaky joints or cleaning hatch in the chimney system.
3: Other buildings create turbulence over or a downdraught in the chimney.
4: Large trees can “shadow” the wind and create a bad draught.
A vacuum can be created in the house so that the chimney does not extract the smoke.
This is particularly prevalent in very airtight houses. See the section “External combustion air”.
The connection between the stove and the chimney must be airtight. The more bends there are and the sharper they are the more resistance and less draught there will be.
SOOT accumulations from chimney cleaning can block the smoke extraction ducts.
BIRDS’ NESTS, typically jackdaw’s nests, can block your chimney. Always check that there the air can flow freely through your chimney before the start of the heating season.
ELEMENTARY OPERATING ERRORS
Firing up with an open ash drawer of to much primary air can cause the stove to overheat with, for example, white windows as a result.
Overfilling of the combustion chamber can cause both the tertiary air and the air wash system to function as primary air whereby combustion is uncontrolled.
If the door is not closed following firing up it can lead to overheating.
Firing up with unsuitable fuel can damage the stove, for example, pressure impregnated wood and plastic create hydrochloric acid which rots the iron, the insulation and the glass.
Here are a few solutions to typical problems
PROBLEM: SOOT HAS FORMED ON THE GLASS.
Cause: Is the temperature in the combustion chamber too low? Is the wood wet?
Is the air supply opened sufficiently? Are there enough embers? Is there sufficient draught in the chimney?
PROBLEM: WATER IS RUNNING DOWN INTO/OVER THE STOVE.
Cause: Condensation from the chimney, wet wood, the temperature in the stove and the chimney is too low.
Wet wood has been used for firing up, there is insufficient wood or air.
PROBLEM: THERE IS NO HEAT COMING FROM THE STOVE.
Cause: Is the air supply opened fully? Is the wood wet? Is the wood too old or dried out?
Has soot formed on the chimney and stove?
PROBLEM: YOU CAN’T GET A FLAME GOING IN THE STOVE.
Cause: Are the baffle plates positioned where they should be? Is there sufficient draught in the chimney? Is the wood wet?
Has soot formed on the chimney and stove? Have the firing up instructions been followed properly?
PROBLEM: IT IS NOT POSSIBLE TO REGULATE THE STOVE, IT IS STILL BURNING EVEN THOUGH THE AIR SUPPLY HAS BEEN CLOSED OFF.
Cause: The stove is not water-tight. Firstly, check whether the sealing bands on the door and the ash drawer are intact and positioned correctly. Contact the dealer.
PROBLEM: THERE IS A SMELL WHEN THE STOVE GETS HOT.
Cause: The paint on the stove is still hardening. To overcome this as quickly as possible it is important that you allow the stove to get really hot the first few times it is used. The paint is not wear-resistant until it has been really hot. Following a summer break, there will often be dust, cobwebs and spiders in the cavity of the stove, this can also cause a smell when it is first fired up.
PROBLEM: THE GLASS IS CRACKED.
Cause: If the glass cracks on the first or second time it is fired up this is reasonable grounds for making a claim. Before the glass is re-inserted – check whether there is any welding slag or other defect that has caused the glass to get wedged in.
If the glass cracks later on this is not normally accepted as grounds for a claim.
PROBLEM: SMOKE COMES OUT WHEN THE DOOR IS OPENED.
Cause: Has the door been opened too quickly? Do not open the door until the wood has burnt down to embers. There must not be any visible flames. Is the wood wet? Is there sufficient draught in the chimney?
PROBLEM: THE GLASS HAS TURNED WHITE.
Cause: This is due to the glass overheating. It happens, for example, if the stove has been fired up too rapidly, with open start-up air/primary air or if unsuitable fuel has been used.
PROBLEM: THE STOVE IS MAKING A NOISE.
Cause: When steel and iron expands rapidly when it gets hot. This places a strain on the welds and joints which sometimes causes a highly audible sound. This is completely normal and quite harmless – it is not a fault or grounds for making a claim. In very rare cases, when the noises can be classified as a a loud “bang” or “pop”, it may be a good idea to ask the dealer for advice.