Low Emission Operation Manual for Chimney Stove
Contents
1. ERA NET Bioenergy Project FutureBio Tec 2 Low emission operation manual for chimney stove users 1 1 Target group This guideline is intended primarily for end users of chimney stoves But it is also meant for professional users such as manufacturers associations or public bodies They are invited to make the guideline available either as a complete paper or by using fragments in their own brochures or product specific manuals Therefore all text photos and images are cleared for publication by third parties without extra inquiry We only request that a reference to this guideline is made 2 Definitions and limitations 2 1 Definition of chimney stove The following features apply to a chimney stove Figure 2 e Itis afree standing room heater not walled and usually with a front window e Only a relatively small amount of heat storage is possible due to the low mass of the stove e Fuel is charged in a single layer onto the ember e Therefore frequent recharging is required e Heat is released by radiation from the window or from other surfaces and by convection via air ducts and outlets Figure 2 Examples of chimney stoves from left to right Wodtke Contura Rika J tul Stanley 2 2 Limitations Much of the technical information in this Guideline also applies to slow heat releasing stoves e g tiled stove inserts closed fire place inserts but such stoves are not the main focus in this document This is due to2. gt pilar mode of stacking without pilar roundwood beams 50 cm Figure 10 Example of proper outdoor storage of covered wood logs on supporting wood beams source TFZ and 6 Storage and drying time Fresh wood has a moisture content of around 45 to 60 when harvested during winter In Central Europe a storage time of a full summer season can be sufficient to achieve a required moisture content of below 20 see Figure 11 assuming that suitable drying conditions are prevailing In Nordic countries and on the British Isles or in humid regions further storage time may be required Wood can also be stored indoors but the room should not be permanently heated and be well ventilated Fuel moisture content SSS CSSS SL SS 3 PS N yer N FE f ER N SE ss Ro Q A p gt eo ge ro Figure 11 Example of drying progress of wood logs stacked and split 1 m pieces in covered outdoor storage piles in Germany source TFZ If fuel is provided from a supplier which applies hot air drying the fuel can in some instances be too dry for immediate use in stoves e g at a moisture content below 8 In such instances storage under the conditions described above can ensure sufficient moisture uptake from the atmosphere into the fuel in order to achieve moisture content levels of 10 or higher
3. ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 11 5 Stove technology 5 1 Design and function In the following a typical design and functioning principle of a modern chimney stove is described For better understanding the following definitions apply Primary air It provides the oxygen needed to gasify the wood fuel and to burn the remaining char in the ember Primary air is directed to the space where the solid fuel is pyrolysed ember Secondary air It is needed to provide oxygen to be mixed with released pyrolysis gases which burn as visible flames Figure 12 shows the flow of gases in a chimney stove For air tight buildings it is required that a combustion air conduit pipe can be connected to the chimney stove via a central air inlet socket 1 Such an air inlet socket can also enable the retrofitting of an electronic combustion air control system via a motor driven flap Post combustion chamber 7 Flue gas outlet 8 Window purge air 3 Deflection plate 6 Main combustion chamber 5 Secondary air 4 Primary air 2 Flue gas Central air inlet 1 gt Combustion air Figure 12 Typical design of a chimney stove here stove with central air supply socket and primary air via grate For buildings which are less air tight or rooms in which the combustion air is usually taken from the heated room itself a central air insertion socket
4. connected by a joint airspace and heated with the designated wood stove reference climate Germany Specific heat demand of the building Nominal heat power output of stove 5 kW 7 kW 9 kW 70 kWh m a gt 100 m gt 100 m gt 100 m i e modern buildings according to the newest insulation standards 160 kWh m a 50 m 70 m 90 m i e medium insulation standard 300 kKWh m a 30 m 40 m 50 m i e older buildings with low insulation standard mean value of building stock in Germany Example In an old building with low insulation standard according to building standards in Central Europe the heat demand is about 300 kWh a For such a building a 7 kW stove would require a minimum of 40 m directly heated living space Table 3 if excessive heat production shall be prevented during normal stove operation Stove selection When purchasing a chimney stove with the required heat power output the following criteria should be considered Air staging Staged air supply should be included to the features of the stove This function is however not always easily visible but it is given for most stoves Separate handles for air adjustment or extra air inlet nozzles can be an indication But high performance stoves can also perform air distribution automatically without any air adjustment handle Check the user manual or the technical documents of the stove Refractory lining The firebox should have a thick refractory lini
5. 2 1 Betihlli n or chimney SstoVe annisie len 2 2 2 EMAON ee ee een ee 2 3 Wood as A UG 28 essen aeg 3 3 1 SIMO COM cies cr ac create ee el ee ne edel ish ee 3 3 2 Permissible fuels in wood stoves cccceecceeeceeeceeeceeeceeceeeceeeceeesaeeceeeseesseeessenseeees 4 3 3 SUILADIC1OG WOOG QUAN ee 5 34 S ltable briquette Ua aaa 7 3 9 Ignition Malerlals usssest seen canner sducanntespeadeiasteansdusstaducartnamesesntateahehetencessmarecalyenys 9 4 Log wood drying storage and quality control u zu2s0220220 nen nenennennenne nennen nee 9 9 Olve Tec NNOO V een none 11 Del Design and TUNCHOM Ener 11 OZ GNOOSING NE TIANESIOVE iseen Ea 12 9 9 POSIHONINO NES SOVE IN a TOON area 15 5 4 Retrofit components and useful ACCESSOTIES ccceceeceeceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeees 15 0 SOVE OPEO ea a whee ala N eettenauae 16 OT JONIVOR 16 6 2 Heating ODE ALON anne 17 6 3 Ash handling and maintenance u2uus2s0200enennennennennonnnnenenenennennennennennn nennen 20 8 4 Troubleshooting anne ee ae E E 21 T ACKIOWEOgGEMERE ee een 22 O Retete raU anne 22 9 Useful sources for further information cc ccccccccccceccccecccccccecccceccececceacenecueauentsneaees 23 ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 1 1 Introduction and objectives All over Europe there is a growing awareness that residential wood fuel applia
6. Electronic combustion air supply control It can be applied if the stove is equipped with a central air inlet socket see also Chapter 5 2 Manostat A manostat pressure guard is a sensor which is located in the room where the stove is operated It is connected to any stationary electric ventilator s which can evacuate the room e g fume extractor When the vacuum exceeds a certain pressure limit e g 4 Pa the ventilator is shut down to prevent disturbance of the combustion Fan on chimney top Such a fan can improve the chimney draught Consult your chimney sweeper Bleed air flap for chimney Flue gas thermometer Electronic air supply control Figure 14 Examples for retrofit components for chimney stoves source TFZ 6 Stove operation 6 1 Ignition Ignition should generally be performed in such a way that high temperatures in the firebox are achieved quickly Top down ignition method This method usually creates best results for stoves Figure 15 e Two or three wood logs are placed horizontally next to each other on the bottom of the firebox e One ignition block is placed onto the logs e The kindling about 2 to 4 sticks are placed crosswise on top e Ensure that all damper s are fully open all the dampers of the stove and any damper in the flue gas pipe e The ignition block is then ignited ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 17 Figure 1
7. Order Implementing the Federal Immission Protection Act Order regarding small and medium firing installations 1 BImSchV 6 HARTMANN H ed 2007 Handbuch Bioenergie Kleinanlagen Published by Fachagentur f r Nachwachsende Rohstoffe FNR Gulzow Germany 224 p Download http www tfz bayern de sonstiges 17745 7 SCH N C HARTMANN H TUROWSKI P 2011 User and fuel impacts on flue gas emission of a chimney stove 19 European Biomass Conference and Exhibition 6 10 June 2011 in Berlin Germany p 960 966 9 Useful sources for further information Alakangas E Erkkila A Ovavainen H Rubik A Englisch M Corbella L Floc h Laizet C Pennequin J Puente F 2008 Efficient and environmentally friendly biomass heating Firewood production and use in fireplaces and stoves Published by Technical Research Centre of Finland VTT 73 p Download www biohousing eu com stoveheating Holzenergie Schweiz 2007 Broschure Richtig Anfeuern Holzfeuerungen mit oberem Abbrand Energie Schweiz Zurich Publikation 315 www holzenergie ch Van Loo S Koppejan J ed 2008 The handbook of biomass combustion and cofiring ISBN 978 1 84407 249 1 Earthscan London UK Certifications schemes and labels for stoves e Nordic Ecolabel for stoves Scandinavian countries http www svanen se en Svanenmarka Kriterier Criteria productGroupID 73001 e DINous label for stoves Germany http www dincer
8. Otherwise the stove will cool down too much An exception from this requirement should only be made if the stove is designed for a single log operation e g if it has an inclined grate The charged wood mass should be achieved by using between 2 logs small stoves of about 5 kW and 4 logs large stoves of about 9 kW Place logs preferably with the bark side downward This usually prevents the bridge formation of a larger bridge with no contact between wood and ember If possible keep a small distance between the logs when placing them onto the ember Also try to keep a distance between the wood and the furnace walls so that air distribution is not disturbed this requirement cannot easily be met when wooden boards are used therefore such fuel is less suitable for stoves Do not overload Never fill up the whole combustion chamber with wood logs In all cases at least half of the height of the firebox should always be left free for the combustion process This requirement can be met easier with hard wood than with soft wood therefore hard wood is preferable ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 19 Recharge your stove using only one layer of logs so that all the wood has direct contact to the ember It is recommended that the wood is placed in the rear part of the stove Avoid placing logs too close to the window where temperatures are lower Do not block any secondary air no
9. of normal or rather small wood logs combined with thinly sliced ignition wood sticks or brushwood or coarse wood chips Figure 8 Such kindling is preferably produced from coniferous wood Figure 8 Kindling wood sticks or coarse wood chips source TFZ Ignition aids Use professional ignition aids as available on the market Such products may be for example e Wax soaked wood wool blocks e Wood fibre blocks with paraffin Figure 9 Ignition aids wax wood wool blocks paraffin wood fibre sticks or blocks source TFZ Do not use the following ignition aids e Paper or carton e Liquid fuels The use of paper for ignition has several disadvantages Due to its leafy ash structure the combustion air flow to the bed of ember is disturbed Also the burning time of paper is too short and unstable to guarantee a reliable ignition In addition ignition happens too slowly 4 Log wood drying storage and quality control For proper storage and natural drying of the logs e Choose windy storage places e Protect the wood against rain by coverage of the top e Protect against surface water by stacking on wooden beams e Ensure sufficient distance to walls or neighbouring stacks gt 0 1 m ERA NET Bioenergy Project FutureBio Tec 10 Low emission operation manual for chimney stove users e Avoid storage of fresh wood in basements or garages e Be aware that short and split wood logs dry faster than unsplit metre wood Bi ee u
10. of preventing excessive ash and soot depositions on their surface Central air socket A central air inlet socket is favourable Such a stove can be applied more universally In highly air tight and or ventilated buildings they are even essential to provide an undisturbed combustion air The socket is connected to a combustion air duct for air supply from outdoors or from the basement e g via a dual wall chimney or via a subsurface air canal The air inlet socket would also facilitate retrofitting of an electronic combustion air control system via a motor driven flap Such a flap could also allow a complete closure of the air inlet in order to prevent heat losses from the room through the natural chimney draught which remains effective even when the stove is not operated and cold Fuel filling mark An orientation mark to indicate the maximum fuel filling height in the firebox is useful to prevent overloading Additional secondary air insertion nozzles see Figure 12 can also provide such orientation User manual The documents and information provided by the manufacturer should be informative and easy to understand The manual should also be stove specific Quality label Look for a quality labelling on the stove In several European countries there are certification schemes for quality stoves Austria Umweltzeichen UZ 37 Germany Dinpius Sweden Nordic Ecolabel Connection to chimney A long flue gas pipe is preferable This is
11. should not be required although it can be useful The combustion air flow into the chimney stove blue area in Figure 12 is divided into e a primary air stream 2 which flows through the grate into the firebox and e a window purge air flow 3 which is conducted to the window top and is then directed through nozzles or slots downward along the window It flushes the window to prevent ERA NET Bioenergy Project FutureBioTec 12 Low emission operation manual for chimney stove users soot or particle depositions But it also serves as combustion air One part of it usually reaches the bed of ember and can provide primary air to the wood fuel if either the grate is closed e g by a rotation rosette or if the grate air damper is locked or if no grate exists at all Another part of this air stream is directed above the bed of ember into the combustion chamber 5 to provide oxygen for the flame combustion Thus it serves as secondary air e Some stoves are equipped with an additional secondary air inlet at the back of the stove wall 4 Such an inlet improves the turbulent mixture of oxygen with the pyrolysis gas released from the solid fuel The portion of this air stream is usually smaller than the window purge air The heat produced in the firebox i e combustion chamber is conserved by a heat resistant mineral insulation layer made of fire clay or chamotte This ensures high temperatures for complete combustion reactions In the post
12. used The diameters D2 and D5 are recommended for cookers and as kindling ignition wood Table 1 Main requirements for traded wood logs defined in European Standard EN 14961 5 3 requirements for most chimney stoves are marked grey Property class Grades Origin and source 1 1 3 Stemwood 1 1 1 Whole trees 1 1 1 Whole trees 1 2 1 Chemically Wout roots without roots untreated wood 1 1 3 Stemwood 1 1 3 Stemwood es 1 1 4 Logging 1 1 4 Logging residues residues 1 2 1 Chemically untreated wood residues D15 lt 15 D15 2 15 actual D10 5sDsi10 value to be stated D15 10 lt D lt 15 D15 gt 15 act value to be stated L20 L25 20 L33 lt 33 25 L50 lt 50 L33 33 L100 lt 100 L L50 50 Length L100 lt 100 Moisture M M20 lt 20 M25 lt 25 wet basis M25 lt 25 M35 lt 35 Volume or weight m stacked To be stated which volume or weight is used when retailed or m loose or kg Proportion of split of pieces 2 90 gt 50 No requirements volume 85 of the firewood should be kept in specified diameter property class Length should be in the limits of 2 cm It is allowed to have 15 firewood shorter than requested length including the limit value Moisture content should not be less 12 w on wet basis M IA IA IA IA ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users T 3 4 Suitable briquette quality A great variety o
13. 5 Ignition module to start the fire from the top source TFZ e After ignition when combustion starts see image Figure 16 the primary air supply to the bed of embers grate air and or primary air dampers shall be closed In addition if required by the manufacturer and if technically possible the secondary air supply has to be reduced slightly Figure 16 Ignition phase and start of wood combustion source TFZ An ignition block burns steadily for about 5 to 7 minutes and provides constant ignition heat while enough combustion air can uninhibitedly passes to the flames and to the already ignited wood this does not easily happen when using paper or carton for ignition because of residual paper ash flakes The traditional bottom up ignition method which is still sometimes used is today not recommended anymore In this old method all fuel including the wood logs is placed above the ignition zone instead of only the kindling With the top down method recommended here a smaller firebox volume is effectively exposed to the small amount of heat radiation that is available and thus the heat losses during this sensitive start up phase are smaller As a result this leads to a faster temperature build up in the zone where it is needed and less fuel is actively used in the ignition process Consequently the residence time of the remaining pyrolysis gases is higher and less unburnt gases leave the firebox 6 2 Heating operation Low emission
14. PF sur A Bioenergy Future Bio Tec Low emission operation manual for chimney stove users Hans Hartmann Claudia Sch n Peter Turowski TFZ Technology and Support Centre Germany Ingwald Obernberger Graz University of Technology Austria Friedrich Biedermann Thomas Brunner Bioenergy 2020 GmbH Austria Linda B fver SP Technical Research Institute of Sweden John Finnan John Carroll Crops Research Centre Ireland Report within the scope of the ERA NET Bioenergy Project FutureBioTec October 2012 Disclaimer The concepts and design guidelines presented are a result of a scientific project The implementation and utilisation of the research results is the decision of each individual person company The authors undertake no liability for the utilisation and implementation of the research work and research results as well as for consequences of the resulting technology development or plant operation Contact BIOENERGY 2020 GmbH Inffeldgasse 21b A 8010 Graz Austria Email office bioenergy2020 eu Tel 43 316 873 9201 www bioenergy2020 eu ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users Preface ERA NET Bioenergy is a network of national research and development programmes focusing on bioenergy which includes 14 funding organisations from 10 European countries Austria Denmark Finland France Germany Ireland The Netherlands Poland Sweden and the United K
15. arted to burn well and for all subsequent batches close the air supply through the grate if a grate is present and operate the stove with the window purge air and if available secondary air When recharging Keep the air supply through the grate closed if a grate is present Stove after shut down Close all openings when the stove is cold and not operated This is to prevent heat losses from the room via the chimney Clean the fire box and empty the ash box regularly otherwise air supply through the grate can be blocked Ash handling and maintenance Rules for ash handling Clean and de ash the stove frequently and follow the manufacturer s instructions user manual When de ashing and cleaning the stove and pipe Do not inhale any released ash particles and avoid any direct contact of your skin with soot use protective equipment such as masks or gloves Carbon and soot containing ashes are known to be poisonous due to high concentrations of polycyclic aromatic hydrocarbons PAH The ash shall be deposited to the residential waste Hot ash should never be placed in unsuitable containers e g of plastic or flammable material Use heat resistant containers Rules for stove maintenance All maintenance and cleaning work is only to be performed when the stove has completely cooled down Check the connecting pipe to the chimney once or twice per year and clean the pipe using a round pipe brush can also be done by chimney swe
16. bernberger Project coordinator ERA NET Bioenergy Project FutureBio Tec Low emission operation manual for chimney stove users FutureBioTec project partners Project coordinator BIOENERGY 2020 GmbH BE2020 in cooperation with Dloenergy2020 Graz University of Technology Institute for Process and Particle Engineering Graz University of Technology University of Eastern Finland UEF Department of Environmental Sciences Fine Particle and Aerosol Technology Laboratory EASTERN FINLAND Kuopio Finland Technology and Support Centre in the Centre of Excellence for Renewable Resources TFZ Straubing Germany Technologie und F rderzentrum Umea University UmU Energy Technology and Thermal Process Chemistry Umea Sweden Lulea University of Technology LTU Division of Energy Engineering Lulea Sweden SP Technical Research Institute of Sweden SP Division of Energy Technology Boras Sweden Institute of Power Engineering lEn Thermal Division Department Warsaw Poland Teagasc Crops Research Centre Carlow Ireland Ac RICULTURE AND F OOD Devetormenr Auruoriry Industrial partners Warma Uunit Ltd Finland APP Applied Plasma Physics AS Norway ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users Table of contents 1 INITOQGUCHOM andLoDJECelVeSs ua este 1 121 bargel 9r0UPp nn teten ee le ee ee 2 2 Definitions and limitations areas El 2
17. building which can exceed the natural chimney draught and thus redirect the flue gases backward through the stove into the room Instant remedial measures are Closure of ventilation opening of window s opening of door s to neighbouring rooms For permanent trouble shooting install a manostat pressure guard as described in Chapter 5 4 e Blockage of a chimney e g dead birds loose bricks Inspect the chimney Dirt deposits on stove window Stoves with a large window area or with ineffective purge air flow tend to ash or soot deposition on the inside of the windows For avoidance use dry wood use smaller recharging mass and smaller logs charge the logs closer to the back wall of the firebox Unusual smell during use after longer shutdown of stove After longer shutdown periods e g summer season the stove can release a bad smell into the room during initial use no smoke This is due to house dust deposits which burn off Heat the stove once to high temperatures and provide fresh air to the room 22 7 ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users Acknowledgement This project was funded within the ERA NET Bioenergy programme Clean Biomass Combustion The project consortium gratefully acknowledges the financial support for carrying out the project provided by Austrian Research Promotion Agency FFG Austria Tekes the Finnish Funding Agency for Technology an
18. combustion chamber 7 combustion is completed therefore high temperatures are here still maintained by refractory lining fire clay or chamotte insulation Also high turbulence is here achieved through the deflection plate 6 which leads the hot gases to the narrow entrance of the post combustion chamber The gases are here finally burnt out and conducted to the flue gas socket from where they exit to the chimney 8 via a connecting pipe In the upper area of the stove the hot flue gases heat the cast iron steel or mineral stove surfaces which reach relatively high temperatures of up to 200 C Even higher temperatures are achieved on the window surface which contributes largely to the heat release into the room An additional heating effect is generated by convection which is created by air flow from ground level passing upward along the stove surface or through convection canals in the stove 5 2 Choosing the right stove Stove power Before selecting a stove the useful heat power has to be determined It depends on the e size of the heated space i e all rooms connected by a joint airspace and the e insulation standard of the building according to the date of erection or renovation Table 3 provides some guidance for proper heat power selection ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 13 Table 3 Selection of proper stove heat power output Minimum required living space of rooms
19. d Innovation Bayerisches Staatsministerium f r Ern hrung Landwirtschaft und Forsten BayStMELF Swedish Energy Agency Swedish Energy Agency Sweden NCBiR National Centre for Research and Narodowe Centrum Development Poland Badan Rozwoju seal ENERGY AUTHORITY Sustainable Energy Authority of Ireland Ireland 8 Related literature 1 OBERNBERGER I BIEDERMANN F BRUNNER T SIPPULA O JOKINIEMI J BOMAN C NIKLASSON F BAFVER L HARTMANN H FINNAN J CAROLL J 2012 Guidelines for the design and application of particle precipitators for residential biomass combustion Report within the scope of the ERA NET Bioenergy Project FutureBioTec October 2012 VIREN A LAMBERG H TISSARI J SIPPULA O JOKINIEMI J OBERNBERGER BIEDERMANN F BRUNNER T HARTMANN H SCHON C TUROWSKI P 2012 Guidelines for Low Emission Chimney Stove Concepts Report within the scope of the ERA NET Bioenergy Project FutureBioTec October 2012 EN 14961 Part 5 Solid biofuels Fuel specifications and classes Part 3 Firewood for non industrial use September 2011 Berlin Beuth Verlag 15 pages EN 14961 Part 3 Solid biofuels Fuel specifications and classes Part 3 Wood briquettes for non industrial use September 2011 Berlin Beuth Verlag 11 pages ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 23 5 1 BImSchV 2010 First
20. e firebox walls when horizontally placed onto the ember Logs should never be so long as to make it necessary to lean them against the walls of the firebox Logs with a uniform medium thickness i e 20 to 30 cm circumference should be used see Figure 5 Split logs should be used in preference of round wood should be split at diameters greater than 8 cm Select thin wood sticks or small logs for the ignition phase Clean and coarse wood chips can also be selected for ignition Small logs are useful for the ignition batch but not recommended for the recharging of the stove The optimal log size is usually specified by the stove manufacturer check the manual Use hardwood rather than softwood if a choice is possible Use logs with low dust or dirt content Figure 5 A circumference of 20 cm corresponds to a diameter of about 9 cm source TFZ ERA NET Bioenergy Project FutureBio Tec 6 Low emission operation manual for chimney stove users Wood fuel standards With the recent creation of European biomass stove manufacturers and fuel suppliers can now make reference to quality classes as given by the log wood fuel standard EN 14961 5 see Table 1 Check for compliance with the new standard But note the fuel supplier is usually not obliged to make reference to the European log wood standard For stoves it is recommended that firewood with a diameter less than 15 cm D10 and D15 and a moisture content less than 20 M20 is
21. ep Check if a firm shutting mechanism of the door is still given and if any door sealing is damaged Adjust the lock or replace the sealing if necessary Check if any refractory lining is broken and if the grate is torn Replace if necessary via customer service The chimney must also be regularly cleaned by a chimney sweeper to avoid soot fire according to the regulations in the respective country For stove specific maintenance requirements check the user manual of the manufacturer ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 21 6 4 Troubleshooting Problems which can occur during stove operation are addressed in the following Permanent danger of smoke release into the room Possible reasons are e Air dampers or the chimney flap of the stove are closed if present Consult the user manual for the stove e Too large or too wet wood logs are used Provide proper fuel e Chimney problems too short chimneys or unsuitable diameters leading to a too low chimney draught Consult your chimney sweeper e Wind is pressed into the chimney due to unsuitable chimney position or length or any deflecting obstacles Consult your chimney sweeper Unexpected smoke release into the room Possible reasons are e Interference with electrical room ventilation systems e g in the bathroom or living room or fume extractor fan e g in the kitchen Such ventilators cause a vacuum in the
22. f briquette types with variable shape and geometry is available Figure 6 Figure 6 Variety of wood briquettes source TFZ If briquette fuel is to be used in the stove the following recommendations are made Check if the fuel supplier declares compliance with any of the quality classes in the new European briquette standard EN 14961 3 as presented in Table 2 But note the supplier is usually not obliged to make reference to the European briquette standard Standard briquettes usually have a low ash content and the concentration of distur bing or polluting components is usually also low e g chlorine nitrogen sulphur or heavy metals If standard quality is certified e g EN pus or DlINpus certification scheme the quality is also monitored Avoid the use of briquettes which are made from 100 bark Such briquettes can lead to smouldering combustion with high gaseous emissions The briquette length should be significantly shorter than the width of the firebox due to swelling during combustion of wood briquettes If volume increase is not allowed for the briquette may get stuck between the sides of the firebox without any contact to the ember Figure 7 Long briquettes therefore need to be broken into shorter lengths before use Figure 7 Swelling of wood briquettes in the firebox The briquette is finally stuck between the walls of the firebox and loses contact to the embers Therefore break longer briquettes bef
23. f wood shavings wood wool wood fibre wax or mineral oil It is not recommended that fuels of herbaceous crop materials are used in a chimney stove even if such fuel is legally permitted in the respective country Fuel that shall be avoided in chimney stoves are e Pure bark briquettes e Straw paper carton and similar products e Painted coated glued wood or wood which is treated with wood protecting chemi cals e g used wood from outdoor applications construction or demolition wood e One way pallets or fruit boxes and similar if any impregnation or impurities cannot reliably be excluded e Other wastes ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 5 These to be avoided fuels are for example in Germany not allowed according to emission regulation 5 3 3 Suitable log wood quality For chimney stoves the following log wood fuel recommendations are given Avoid wet wood Moisture content should be below 20 wet basis When mould is visible on the surface the log may be too wet Avoid over dried wood logs Moisture content should not be below 8 Wood from long storage in a heated room can be over dried Wood which comes directly from fuel producers using hot ventilation for drying can also be over dried After intermediate storage in ambient air such wood is again suitable for stoves The logs should have a length which allows for several centimetres clearance to th
24. he project focused on the following main objectives e The further development of wood stoves towards significantly decreased CO OGC PM and NO emissions by primary measures air staging and air distribution grate design and implementation of automated process control systems e The improvement of automated furnaces in the residential and the small to medium scale lt 20 MW capacity range towards lower PM and NO emissions by primary measures staged combustion utilisation of additives as well as fuel blending e The evaluation development and optimisation of secondary measures for PM emission reduction in residential biomass combustion systems In order to reach these objectives a consortium of 8 research organisations and 2 industrial partners from 7 European countries collaborated within FutureBioTec see next page This document summarizes all scientific and practical Knowledge which was collected and discussed in the project consortium to provide a sound and general guidance to the end user of a chimney stove which is used with wood logs or wood briquettes It covers the most important aspects for the choice functioning and operation of a stove Results from research which was performed within the project were considered and general knowledge from literature and industry was collected and systematically evaluated in order to reflect the best practise for such heating appliances according to the modern state of the art Ingwald O
25. ing wood drying the calorific value of wood and also the total energy content of a specific volume increases For example a stacked cubic metre of beech wood logs of 33 cm length at 15 moisture content has an energy content which is equivalent to about 190 litres of heating oil Figure 4 ERA NET Bioenergy Project FutureBioTec 4 Low emission operation manual for chimney stove users 2500 250 kWh 1 m stacked beech wood logs 33 cm 2000 Litres 1500 100 1000 Pa 100 1 m stacked spruce wood logs 33 cm 900 50 Energy content in kilowatt hours Energy content in litres heating oil 0 10 20 30 40 50 60 Moisture content Figure 4 Fuel moisture content affects the energy content of a stock of wood heating values are based on net calorific value source TFZ 3 2 Permissible fuels in wood stoves The technically permissible fuels for a chimney stove are usually listed in the manual of the manufacturer Newer stoves usually mention the permissible fuels on the identification plate Permissible fuels are usually e Natural untreated wood which is either round wood or wood split into logs with or without adherent bark e Sawn wood scantlings boards with or without adherent bark e Wood briquettes made from natural untreated wood e Ignition fuels in small quantity coarse wood chips brushwood sticks kindlings e Ignition aids only in small quantity made o
26. ingdom Its mission is to enhance the quality and cost effectiveness of European bioenergy research programmes through coordination and cooperation between EU Member States The project FutureBioTec Future Low Emission Biomass Combustion Systems has been supported in the period between October 2009 and September 2012 by ERA NET Bioenergy under the joint call on Clean Biomass Combustion from 2009 The European Union and its member States aim at an increased use of renewable energy in order to avoid a further increase in atmospheric CO concentrations and therefore the European Commission actively supports the utilisation of biomass for energy production However this aim must be achieved without increasing other harmful emissions such as fine particulate matter PM nitric oxides NO carbon monoxide CO and organic compounds OGC PAH Therefore especially regarding the small and medium scale heating sector where a great potential for biomass utilisation all over Europe exists the promotion of energy from biomass must be accompanied by further technology development towards low emission combustion systems Against this background the project FutureBioTec aimed to provide a substantial contribution concerning the development of future low emission stoves and automated small and medium scale biomass combustion systems lt 20 MW Considering the different states of development of the combustion technologies and capacity ranges addressed t
27. nces are potentially responsible for a great deal of environmental hazards The complaints are mani fold particle emissions are dangerous to health bad smell is annoying wood is used inefficiently sometimes illegal fuel waste is burnt regional particle emission limits are violated etc Consequently regulations and restrictions for wood combustion are now being revised in many European countries At the same time the performance of stoves and knowledge about proper stove technology are progressing and there are various technical and non technical measures which can be undertaken to avoid the problems described above the end user can today choose between much better stove products than in the past He can also optimize the integration of a wood stove into his heating infrastructure But above all it is the end user s heating behaviour i e fuel selection stove operation and maintenance which is most decisive for achieving high efficiency and low emissions Figure 1 Avoidable pollutant emissions from residential wood combustion source TFZ Therefore this guideline is intended to help prevent hazardous combustion performances of chimney stoves which represent todays largest group of appliances The guideline aims at supporting end users in the operation of their stove It provides useful information about the influences and mistakes which can occur during wood stove selection installation ignition charging operation and maintenance
28. ng to protect the steel or cast iron from high temperatures and to reduce heat losses The refractory lining also improves the heat storage and serves as a buffer for the otherwise much more variable combustion temperatures Firebox geometry A high and slim combustion chamber geometry is usually preferable compared to a wide and low shape of the firebox although the smaller base area may then require shorter wood logs A high and slim shape improves flame dispersion and leads to a more homogeneous residence pattern for the produced pyrolysis gases in the hot zones i e less danger of short circuit flows to the exhaust pipe Construction Look for robust construction with no loose parts good welding lines and a firm shutting mechanism for the door Air tightness A robust construction will usually lower the risk of false air inlet Such uncontrolled leakage air disturbs the designed and optimized combustion air 14 ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users distribution and can reduce the air staging effect In this respect the hinges and the locking system of the front door usually represent a particular weak point Window A small window reduces heat losses from the combustion chamber thus it is preferable Double glazed windows with an air gap are beneficial Windows using special glass with low heat transmission are also favourable Such windows also have the additional advantage
29. ore charging source TFZ ERA NET Bioenergy Project FutureBio Tec 8 Low emission operation manual for chimney stove users Table 2 Main requirements for traded wood briquettes defined in EN 14961 3 for use in most chimney stoves the recommended briquette class is A1 4 Property class Unit Grades LAT e f gt Origin and source 1 1 3 Stemwood 1 1 1 Whole trees 1 1 Forest without roots plantation and other 1 2 1 Chemically virgin wood untreated wood 1 1 3 Stemwood residues l 1 2 By products ee and residues from wood processing 1 1 6 Bark industry 1 2 1 Chemically 1 3 Used wood untreated wood residues Moisture M as M12 lt 12 M15 lt 15 M15 lt 15 received Ash A dry A0 7 lt 0 7 A1 5 lt 1 5 A3 0 s 3 0 Particle density DE DE1 0 2 1 0 DE1 0 2 1 0 DEO 9 20 9 Additives dry lt 2 lt 2 lt 2 Type and amount to Type and amount Type and amount to be stated to be stated be stated kWh kg Q4 3 24 3 Q4 25 2 4 25 Q4 15 2 4 15 Type of additives to aid production delivery or combustion e g pressing aids slagging inhibitors or any other additives like starch corn flour potato flour vegetable oil Also additives which are used after production before unloading to end user storages shall be stated similarly type and amount ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 9 3 9 Ignition materials Kindling For the first fuel batch select a number
30. s and high efficiencies are achieved with chimney stoves if the recom mendations given here are followed Recharging procedure e Contrary to slow heat releasing stoves a chimney stove requires frequent fuel char ging e The maximum mass which can be loaded per batch is usually mentioned in the user manual for the stove 18 Figure 17 Recharge shortly before the ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users The stove is usually well operated if awood mass of around 0 15 kg per kilowatt of nominal heating power is charged every half hour For a 6 kW chimney stove this means that about 0 9 kg fuel is charged every 30 minutes The recharging is typically performed when the flames die down while the bed of ember is still covering the grate see Figure 17 below If recharging does not occur the temperature in the firebox would rapidly decrease from this point see Figure 18 and the emission level would increase flames extinguish source TFZ To recharge open the chimney stove door slowly Reason In rare cases the fast availability of oxygen can lead to spontaneous ignition of hot pyrolysis gases accumulated in the firebox which can cause injuries from an explosive flame If necessary level the bed of ember smoothly before adding new wood into the oven Use either a wood log or a poker The use of heat protecting gloves may be required Avoid the charging of only a single log
31. tco de de kaminoefen pelletoefen heizeinsaetze herde und _sonsti ge_haeusliche heizgeraete html e Austrian Umweltzeichen UZ 37 http www umweltzeichen at cms homef fuer interessierte richtlinien content html
32. the high variation of their designs and features which would make it difficult to give generalized recommendations Consequently tiled stoves open fire ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 3 places cooking stoves all stoves with water jackets pellet stoves and sauna stoves are not covered in this guideline Apart from all practical questions concerning stove proper selection and operation further technical improvements are also possible e g by a better stove design or by special flue gas treatment But such primary and secondary measures are separately presented in other guidelines which have also been prepared during this ERA NET project see 1 and 2 3 Wood as a fuel 3 1 Energy content The replacement of 1 litre of mineral heating oil energy content 10 kWh requires about 2 3 kg of air dried wood or 2 1 kg wood briquettes Figure 3 e Available fuel energy is determined by the weight rather than by the fuel volume e The calorific value of 1 kg dry wood is almost consistent for all wood species 3 e The calorific value by mass largely depends on the moisture content of the fuel e Young thin wood has a higher ash content than old thick wood it contains more bark 2 4 kg 2 1 kg 1 7 kg 1 litre Softwood Hardwood Wood briquette Brown coal Heating oil briquette Figure 3 Fuel masses of equal energy contents of 10 kWh 36 MJ source TFZ Dur
33. uitability of the chimney and the combustion air provision pipe bushing with fire resistant protecting shell 4 vertical flue gas pipe inflammable wall max allowed surface 20 cm each temperature 85 C _ ee safety distance at back min 20 cm distance at front min 50 cm lateral un IT min 30 cm spark resistant floor cover for inflammable floors e g glas metal concrete tiles Figure 13 Usual requirements and safety distances for the installation of a chimney stove in rooms with inflammable walls and floor materials 6 5 4 Retrofit components and useful accessories A stove can be equipped with the following retrofit components Figure 14 for improved combustion performance Flue gas thermometer It allows to identify proper charging times Such thermometers are available from specialized suppliers Their emplacement requires a small hole in the flue gas pipe but magnetic thermometer designs are also available Bleed air flap It is fitted at the chimney bottom e g in the basement to avoid excessive chimney draught Consult the chimney sweeper for further advice For stoves with central air inlet socket a special bleed air flap can also be mounted at the stove s flue gas outlet and via a t fitting be connected to the central air canal to allow combustion air to bypass the stove ERA NET Bioenergy Project FutureBioTec 16 Low emission operation manual for chimney stove users
34. usually achieved by using the vertical pipe outlet of the stove The probably also available horizontal flue gas pipe outlet is less suitable This is because the shorter pipe prevents significant heat portions from being transmitted into the room before reaching the chimney Using the vertical flue gas outlet will in most cases also have the positive effect that the flue gas passes the final combustion space in the stove burnout and heat exchanger zone more consistently which can further increase the efficiency and reduce emissions Automatic control Some modern stoves provide an automatic combustion air control It can either be electronical via motor driven flaps or thermomechanic flaps are operated via a temperature sensitive expandable liquid Such functions are usually advantageous as they offer an optimized combustion and they prevent false operations such as an omitted closure of grate air flow after the initial heating phase ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users 15 5 3 Positioning the stove in a room For safe operation of the stove some requirements regarding the distance to walls or other objects must be considered Some useful recommendations are given in Figure 13 It is strongly suggested to consult the local chimney sweeper before selecting and erecting the stove In some countries this consultation is even obligatory e g in Germany The chimney sweeper evaluates the s
35. zzles when charging such air nozzles are sometimes placed in the rear refractory lining e g as small holes or slits about half way up in the firebox see Figure 12 For the determination of the correct charging time the stove thermometer see Figure 14 can provide some guidance if installed The correct temperature for charging can be identified by observing the rapid temperature drop after the flames are extinguished Charging should take place at the beginning of this rapid temperature drop Figure 18 or with some experience slightly before Max D ae gt me Flame L extinction Min nn SF Burning time Figure 18 Recommended charging time at flame extinction when the flue gas temperature declines Avoid overloading rapidly source TFZ Do not use very small logs for recharging the stove This will lead to higher pollutant emissions due to too fast pyrolysis and oxygen deficiency The very small logs should be saved for the next ignition batch Adequate log sizes are between 7 and 9cm in diameter see Figure 5 Avoid too long logs Avoid charging with Avoid large space only one big log between logs Figure 19 False operation of a chimney stove source TFZ 20 ERA NET Bioenergy Project FutureBioTec Low emission operation manual for chimney stove users Air adjustments 6 3 For ignition Open all dampers during ignition After the logs have st
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