Planning document Issue 01/2009. Planning document. Solid fuel boiler Logano S151, S231 and S241/SX241 with 15 kw to 52 kw. Heat is our element

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1 Planning document Planning document Issue 01/2009 Solid fuel boiler Logano S151, S231 and S241/SX241 with 15 kw to 52 kw Heat is our element

2 Contents Contents 1 Buderus solid fuel boiler Logano Types and output Possible applications Features and key benefits Basic principles Why heat with wood? Wood as fuel Preparation of logs Combustion process Correct heating with wood Planning wood boiler systems Technical description Logano S151 wood gasification boiler Logano S231 special wood boiler Logano S241/SX241 special wood boiler Dimensions and specification Boiler parameters Regulations and operating conditions Extracts from the regulations German Iissions Act Operating requirements Corrosion protection in heating systems Sizing the wood boiler system Basic principles Dual-fuel boiler combinations Stand-alone wood boiler systems Sizing the buffer cylinder Necessity of the buffer cylinder Determining the size of the buffer cylinder Selection of the Buderus Logalux buffer cylinders Freshwater station in connection with Buderus buffer cylinder Heating control unit control unit for Logano S SX control units for Logano S Control units for Logano S241/SX Control units for additional control functions Function overview of control configuration control unit as stand-alone heating circuit controller

3 Contents 8 System examples Information regarding all system examples Safety equipment Stand-alone wood combustion systems Dual-fuel boiler systems (alternative operation) Dual-fuel boiler systems (serial operation) Hydraulic detail for wall mounted gas boilers Installation Transport and handling Installation room conditions Installed dimensions Additional safety equipment Additional accessories Flue system General requirements Flue connection Flue gas parameters Index Annex

4 1 Buderus solid fuel boiler Logano 1 Buderus solid fuel boiler Logano 1.1 Types and output Logano S151 in six boiler sizes with rated output from 14.9 kw to 40 kw (maximum log length: 0.33 m for 15 kw and 20 kw; 0.5 m for 25 kw to 40 kw). Logano S231 in one boiler size with rated output from 33 kw to 52 kw (maximum log length: 0.5 m). Logano S241 and SX241 (with Lambda control) each in three boiler sizes and rated output from 23 kw to 30 kw (maximum log length: 0.5 m). Can be combined with buffer cylinders, thermal store buffer cylinders, combi cylinders and thermal store combi cylinders with different capacities. 1.2 Possible applications Buderus solid fuel boilers Logano S151, Logano S231 and Logano S241/SX241 are suitable for all heating systems compliant with DIN EN They are used for central and DHW heating in detached and twofamily houses. Subject to application, supply reliability or charging options, they are used in stand-alone heating system or so-called dual-fuel boiler combinations. 1.3 Features and key benefits Logano S151 wood gasification boiler Low emissions Performance better than the limits set by the German Iissions Act. High efficiency Radiation and standby heat losses are kept low through excellent thermal insulation. Clean combustion and efficient operation The boiler is designed for low down combustion (down draught principle) and is ideally suited to wood combustion. The boiler is charged from the front. The combustion chamber is lined with fireclay and equipped with flue gas reversal, resulting in high fuel utilisation and low emissions. Convenient operation The boiler is equipped with a heat-up flap for easy heat-up and safe recharging. The hopper and ash compartments are sized for convenient, continuous combustion times. Safety For operation in sealed unvented heating systems to DIN EN , the boiler is equipped as standard with a safety heat exchanger. Excess heat is transferred via this exchanger and a thermally activated safety valve (available as an accessory) up to the full boiler output. The heat exchanger is TÜVapproved. As standard, a flue gas fan is fitted to assist with starting, as a security feature when recharging, to control output and balance out draught fluctuations in the flue system. 4

5 Buderus solid fuel boiler Logano Logano S231 special wood boiler Low emissions Performance better than the limits set by the German Iissions Act. High efficiency The combination of low down combustion with the patented TURBOAIR secondary combustion, plus the generously sized heating surfaces enable high boiler efficiency levels to be achieved. Robust and durable All surfaces in contact with hot gases are made from 10 thick steel. Maintenance-intensive parts and sensors have been deliberately excluded. Convenient operation A sloping hopper door in conjunction with the flue gas fan ensure safe and easy charging. Nominal combustion time up to seven hours at full load means convenient heating. Easy maintenance and cleaning The extremely clean combustion and completely smooth heating surfaces make cleaning a very quick affair. A large ash box, large cleaning door and cleaning apertures on both sides makes for easy handling Logano S241/SX241 special wood boiler Clean combustion and efficient operation Wood gasification boiler with low down combustion and a fireclay-lined combustion chamber with flue gas reversal for clean combustion and highest efficiency. Lowest emissions Performance significantly better than the limits set by legal orders and current subsidy prograes (at the time of going to print). Easy and convenient operation Long combustion times up to 6 hours thanks to the large hopper. Logano S241 Standard control unit with integral differential temperature control for buffer cylinder heating and as protection against unintentional buffer discharge. Logano SX241 Ixtronic control unit with Lambda control for regulating the buffer cylinder primary pump. Quick installation, coissioning and maintenance Easy integration of boiler into an existing system. Easily accessible combustion chamber and secondary combustion zone with smooth heating surfaces for easy cleaning. 5

6 2 Basic principles 2 Basic principles 2.1 Why heat with wood? Rethinking energy consumption The constant expansion of the supply network for the fossil fuels natural gas and fuel oil, and a somewhat one-sided ecological perception meant that over the past decades, solid fuels had the rather dubious reputation of being "dirty" and "old hat". Advanced wood boilers are now proving the opposite, supported by a rethink of our energy consumption in general. However, the above circumstances resulted, particularly in Germany, in a drastic decline in the sales, planning and installation of solid fuel boilers. In general, this was accompanied by a loss of expertise in engineering and the trade. This document is designed to give engineers and heating system builders a solid foundation for the technically sound planning and implementation of advanced heating systems with wood boilers. In discussing energy resources, the environment and climate protection, the quest for environmentally compatible and sustainable fuels increasingly gains in importance. The main focus currently lies with the utilisation of solar energy. However, particularly wood as a fuel that stores solar energy offers crucial benefits compared with other especially fossil fuels. CO 2 neutral combustion During combustion, wood releases the same amount of carbon dioxide (CO 2 ) as it absorbs during its lifetime. Photosynthesis keeps the carbon dioxide within the perpetual cycle: plants and trees absorb CO 2, minerals, water (H 2 O) and sunlight whilst they grow, and in return give off, amongst other things, oxygen (O 2 ) to their surroundings ( 6/1). Oil and gas as fossil fuels bound their carbon millions of years ago. When they are burned today in enormous quantities is no CO 2 cycle, unlike with wood combustion. Sustainable energy form Wood is a sustainable raw material and fuel that is constantly regrown, not least because of solar energy. When wood burns, the "stored" solar energy is released. In sustainable forestry, there is a constant supply of wood that can be used as a material, raw material and fuel. The sustainable forestry economy thereby contributes to the protection and retention of the forest ecosystem that is vital to our survival. Rotting Carbon dioxide (CO 2 ) Oxygen (O 2 ) Carbon (C) 6/1 Photosynthesis and CO 2 cycle Combustion Carbon dioxide (CO 2 ) Oxygen (O 2 ) Carbon (C) H 2 O Low supply energy expenditure and environmentally responsible handling CO 2 Wood does not grow in any one central location and therefore necessitates no long transport paths that could be detrimental to the environment. Preparing wood as a fuel does not require much energy and is low tech compared to other types of fuel. Wood can be transported and stored without any great risk to the environment. Apart from these and all the other benefits of wood as a fuel, it should be noted that wood from German sustainable forestry can only cover a part of the current primary energy consumption. Consequently, wood can be only one of many energy forms that mankind needs to learn to use sustainably. However, of all the alternative renewable fuels, wood is the one with the largest potential that can be made available quickly and easily. Correctly applied, the combustion of wood provides heating with excellent environmental credentials. The quality of the energy conversion depends largely on the operating method of the system user, the hydraulic integration and control, the design of the heat source and the fuel itself. The above aspects should be illustrated in this document using the combustion of logs in central heating boilers, the currently most coon form of utilising wood as fuel, by way of an example. O 2 6 CO H 2 O C 6 H 12 O O 2 Chlorophyll 6

7 Basic principles Wood as fuel Wood compared with other solid fuels Essentially, wood is made from cellulose and lignin. Subject to the type of wood, resin, fats and oils are also present. The elementary composition of different types of wood is very similar. However, the difference to other solid fuels is substantial. Constituents and calorific value Solid fuel Wood (air dried) Lignite briquettes Anthracite Coke Carbon (C) % Hydrogen (H) % Oxygen (O) % Nitrogen (N) % Sulphur (S) % Water (H 2 O) % Ash % Calorific value kwh/kg /1 Chemical composition in percent and calorific values of solid fuels Calorific value of different types of wood The different chemical composition alone makes clear that for ecologically and economically optimised fuel utilisation, different solid fuel boilers must be used that are tailored to the specific fuel type. The fuel composition gives wood a lower specific calorific value than other fuel types. The specific calorific values of the various types of wood are relevant for an economic comparison. Hardwood, such as beech has a higher calorific value, relative to volume, than softwood. However, the calorific value of wood is strongly dependent on the moisture content of the wood. Type of wood Calorific value 1) Comparison of calorific values kwh/ Natural gas L Natural gas E 2) Oil Pellet kwh/kg stacked cubic metre kwh/m³ kwh/m³ kwh/l kwh/kg Beech, oak, ash Maple, birch Poplar Spruce, larch, douglas fir Pine, fir /2 Specific calorific value of wood 1) Wood in an air dried state with 15 % water content 2) Share of natural gas E in Germany approx. 75 % Units of measurement for wood To determine an amount of wood, there are many units of measurement that must be carefully differentiated. The following table suarises the most coon units of measurement. Conversion 1 solid cubic metre corresponds to 1.4 stacked cubic metres. 1 tipped cubic metre corresponds to 0.6 stacked cubic metres. Round timber in solid cubic metres Stacked timber in stere or stacked cubic metres /3 Units of measurement for wood Logs (0.33 m) in tipped cubic metres 7

8 2 Basic principles 2.3 Preparation of logs Moisture content of wood Wet wood always offers less available heat than dry wood, i.e. the wetter the wood the less available energy there is. The water content in wood evaporates during combustion. This process requires energy. Consequently, with an increasing water content in the wood, a corresponding proportion of the energy contained therein is lost with the water vapour and can therefore not be used for heating purposes. In principle, the utilisation of the heat in the water vapour condensing technology would also be possible here, but its development is currently not ready for the market. Freshly cut "green" wood contains more than 50 % water and consequently offers only half the calorific value of dry wood with 15 % water content ( 8/1). It is therefore uneconomical and harmful to burn wet wood, as with a water content in excess of 25 % to 30 %, smouldering fire with prohibited smoke development and unpleasant fumes can result. The high water content reduces the combustion temperature. Increased soot and tar formation, the risk of soot deposits forming in the chimney and a general increase in harmful emissions will result. Therefore, to prevent combustion with greater environmental damage, only air dried wood with a water content below 20 % should be used for heating. H i [kwh/kg] 5 4, , /1 Calorific value (approximately) of wood, subject to water content Key to diagram H i Calorific value ϕ Moisture content w Water content w [%] ϕ [%] Splitting logs For optimum combustion, it is particularly important that the pieces of wood are split. The wood should be split iediately after being felled. Splitting is beneficial to drying, as a specific larger surface area is available that enables or accelerates the drying process. However, there is an even greater value to splitting that is explained by means of a statement that on initial inspection would seem rather provocative: "Wood does not burn, it develops gases". Wood fuel consists predominantly of gaseous materials that are easily flaable near a source of ignition. Good gas development is therefore required to provide good, quick combustion. Good gas development is (only) assured at the "fractured" point, making splitting a must. The mechanics of wood combustion are substantially different to those of burning liquid or gaseous fuels. To keep this text comprehensible, there will be no detailed description here of the complex processes involved. A further influencing factor for the optimum combustion of wood is not only the splitting of the firewood, but also its physical size. For small combustion systems in detached and two-family houses, the maximum diameter or maximum edge length should never exceed 15 cm. Compared to their mass, smaller pieces of wood have a greater surface area than large pieces. They ignite much more easily and offer the flame a larger area of attack, bringing about drying, degasification and burnout more rapidly. Larger pieces of wood can slow down combustion if they have an unfavourable ratio between volume and surface area. Inevitably, this leads to lower combustion temperatures and higher noxious emissions. 8

9 Basic principles Drying of firewood (split logs) Storage location Apart from the mechanical processing steps, the correct storage of wood is important. The water content of freshly split logs stored in the open under a roof is not only dependent on the length of storage but also on the ambient influences. A log that is ready for use should be stored loosely and be protected from rain by a roof. In addition it should be ensured that there is a gap between the individual layers of wood to enable the flowing air to absorb the expelled moisture ( 9/1). Never store fresh wood in a cellar, as it would not sufficiently dry there; instead hydraulic obstruction would result. Splits logs should ideally be piled up in a well ventilated, sunny, south-facing spot protected from rain. Wood should therefore not be packed in foil or similar when stored to dry. During the drying phase, good ventilation is the most crucial factor /1 Wood storage (dimensions in cm) Storage duration Rule of thumb: for softwood, at least one year; for hardwood at least two years of drying are required. Two to three years' drying are preferable ( 9/2) ϕ [%] Januar Juli Januar Juli Januar t L [Monate] 9/2 General diagram of the moisture content of firewood compared to the length of storage Key to diagram ϕ Moisture content Storage duration t L 9

10 2 Basic principles 2.4 Combustion process Combustion chamber for wood Wood is rich in gases and therefore a fuel that produces a flame for a long time ( 10/1); consequently it requires a sufficiently large combustion chamber for the combustion process. The actual idealised combustion process can be split into several phases ( 10/2). Key to diagram a Coke b Forge coal c Lignite briquettes d Wood Volatile constituents [%] a b c d 10/1 Flame length for different fuels Combustion phases of wood For reasons of simplicity and daily use, we should differentiate between the following combustion phases ( 10/2) Drying phase The fuel begins to be dried as soon as combustion starts. In this phase, above 100 C the water contained in the wood evaporates and is removed from the fuel. Degasification phase After drying, at temperatures above 250 C the wood degasifies. At this temperature, the wood begins to split open and the constituents of wood, such as cellulose, resins, oils etc. degasify. At temperatures above 500 C, almost the entire cellulose will have been converted into the gaseous phase. After these volatile constituents have developed into gases, the charcoal (solid carbon constituents) then gasifies. Combustion phase The combustion (oxidation) of the released gases coences at approx. 700 C and in reality reaches temperatures in excess of 1200 C. In a single piece of wood, all phases can occur simultaneously from the inside out. High combustion temperatures and long dwell times of the gases in the combustion zone ensure good combustion with minimum noxious emissions. One prerequisite for this is an adequate supply of combustion air, since wood should burn with a constant flame. Combustion over time t [s] 10/2 Wood combustion phases in time sequence Key to diagram t Time 1 Ignition 2 Drying 3 Degasification (pyrolysis) 4 Gasification of solid carbon particles 5 Combustion of the products of degasification and gasification

11 Basic principles Low down combustion principle In low down combustion, only the lowest layer of the fuel bed is involved in combustion. The combustion gases released in the area of the primary air are routed by a flue fan into a combustion chamber below (down draught for the Logano S151 and S241/SX241) or next to the fuel hopper (for the Logano S231), where they burn (secondary combustion) with added secondary air. The wood located above the incandescent zone acts as fuel reserve that automatically falls down as the current charge burns, enabling a practically continuous fuel charge. The combustion principle of low down combustion combined with the large fill volume means that there is no need for frequent recharging. Combustion can take up to five hours or longer ( 11/2). Low down combustion enables a relatively continuous pyrolytic decomposition and degasification of the fuel. This improves the matching of the combustion air volume to the released amount of combustion gases. The result is good complete combustion and consequently a high combustion quality. Primary 11/1 Low down combustion principle Secondary Combustion over time [g/s] t [s] 11/2 Low down combustion Key to diagram ( 11/2) t Time 11

12 2 Basic principles 2.5 Correct heating with wood To prevent unnecessary pollution users should pay particular attention to the heating operation. Only fuel that is intended for the specific boiler should be used. Even this apparently trivial requirement is frequently ignored in practical applications, although it is one of the most critical conditions to be met Correct charging Wood needs to be heated up and burned with an adequate supply of combustion air and with a flame. Therefore use kindling for heating up. This enables a high combustion speed with the result that a good incandescence builds up. After the heat-up process, correct charging is also crucial for good combustion results with low emissions. The most coon practice, i.e. to fill the boiler to the brim and then let all the fuel burn, is (in operation without a buffer cylinder) fundamentally wrong. The consequences of poor partial load operation are severe tar and soot formation, soot emissions, additional boiler contamination, low efficiency and high levels of emissions. Only via measured charging, tailored to the heat consumption, can satisfactory operation be achieved. Practical results provide clear evidence that in partial load operation with a fully charged combustion chamber and insufficient heat consumption, dust and CO emissions can rise by a significant factor. The main condition for clean combustion in partial load operation is that less firewood should be filled more frequently, rather than a large amount at once Combustion air and boiler water temperature Trouble-free and environmentally responsible combustion of wood can only be achieved, for the reasons stated above, with an adequate supply of combustion air and correspondingly high boiler water temperatures as well as a good temperature spread in the reaction zones. Particularly for central heating boilers with water-cooled heating surfaces, it is important to operate the boiler with higher boiler water temperatures when burning wood. For wood boilers, boiler water temperatures above 65 C are recoended. When heating up it should be noted that the cold start phase below 50 C is passed as quickly as possible. Advanced control technology supports this operating mode. 12

13 Basic principles Planning wood boiler systems Boiler selection Today, solid fuel boilers must compete in the most diverse areas with proven oil or gas boilers - naturally within the framework of fuel characteristics. By way of an example, we should mention reliability and handling. In addition, environmental compatibility is a central point of discussion in the current energy economy. Where the combustion of solid fuels is concerned, the 1st BImSchV and (regional) subsidy prograes [in Germany], which include some very strict limits regarding CO and dust, have propelled the development of advanced boilers forward. These demands have increased the trend towards special boilers, enabling current requirements to be met only with designs that are tailored to their specific type of fuel. Solid fuel boilers as "omnivores" or even "waste combustion systems" are therefore definitely a thing of the past. The adjacent selection list demonstrates clearly that many criteria can or should be considered to make the right choice of boiler. Apart from fundamental requirements made of boiler technology, user demands must be clarified in the early stages of planning. Only that way can systems be planned, created and operated in a way that is satisfactory for all participants. Selection criteria Separately selectable combustion air supply: the primary air for wood fuel (combustion chamber) and the secondary air for secondary combustion of the released hot gases (secondary combustion zone) Non-cooled secondary combustion zone with intensive mixing of air and hot gases Large secondary heating surfaces for good energy utilisation Combustion with adequate amounts of excess air High combustion temperatures with adequate hot gas dwell time Nominal combustion time to be achieved at full load Maximum length of split logs to be used Power consumption for essential auxiliary drives (fans, control drives,...) Ease of service Possible system integration 13

14 2 Basic principles Combination with a buffer cylinder In conjunction with an adequately sized buffer cylinder, the problems often associated with partial load operation can be elegantly avoided. The wood boiler will then almost always operate in the full load range. Benefits of a buffer cylinder The solid fuel boiler can always be operated in the advantageous full load range now even during spring and autumn when there is a low heat demand, or in suer only for DHW heating. The utilisation of the boiler system can be extended to all-year operation when DHW heating in suer is included, resulting in a very favourable cost/benefit ratio. The economy of the solid fuel boiler system is raised to the highest level in several respects, and the fuel is utilised in the best possible way. Partial load operation with all its adverse operating results is sensibly avoided. Environmental pollution is significantly reduced as the solid fuel can be burned under ideal conditions and emissions are reduced. Smouldering combustion and its associated prohibited and avoidable environmental pollution are largely avoided. The control interval limits should be arranged so that the solid fuel boiler is fired at the most favourable times of the day. Even when burning solid fuel with a relatively low calorific value, such as wood, moderate heating operation at night can be maintained. The heat will be drawn from the buffer cylinder. Apart from convenience, comfort and economy are also improved by the automatic advanced heating control via the buffer cylinder. The operating results are therefore equal to any other advanced heating system. The system safety is markedly improved. The thermally activated safety valve rarely responds; in most systems it does not respond at all, subject to the buffer cylinder being adequately sized. Boiler maintenance is made substantially easier. There are no more solid deposits when dry wood, or wood that is not exclusively rich in resins, is burned Conclusion Used correctly, wood is a fuel that makes ecological sense. Correct engineering, installation and operation of an advanced wood boiler system requires well-grounded background knowledge regarding wood as a fuel. This knowledge will result in the recognition that an adequately sized buffer cylinder is a must for such systems. For good reason then, buffer cylinders for wood boiler systems above 15 kw output are even a requirement specified by the German Iissions Act ( Chapter 4). Modern wood boilers in conjunction with a buffer cylinder offer operating results that must in no way be second best to oil/gas heating systems. When planning a wood boiler system, many complex factors need to be considered to achieve the installation of a well-functioning, economical system. The interaction between well thought-out system design and a suitable, high grade boiler with controls to suit the specific fuel is the ticket to the environmentally compatible, futureproof utilisation of wood as a fuel. 14

15 Technical description 3 3 Technical description 3.1 Logano S151 wood gasification boiler Logano S151 equipment level General Output for detached houses and apartment buildings Combination boiler for dual-fuel boiler combinations or as a stand-alone heat source 2114 control unit for simple connection to Buderus oil/gas boilers with heating circuit control units Includes safety heat exchanger for the connection of a thermally activated safety valve Low emissions, significantly below the permissible limits set by the German Iissions Act Long combustion time Output 14.9 kw to 40 kw Fuels Logs (up to 0.33 m for 15 kw and 20 kw and up to 0.5 m for 25 kw to 40 kw) Special features Down draught technology with specific primary and secondary air routing Fireclay-lined combustion chamber with flue gas reversal for low emissions Low down combustion with up to 86 % efficiency Minimum radiation losses through all-round good thermal insulation Fully automatic operation with heat-up monitoring after starting Hopper door with safety interlock Automatic fan start Heat-up flap with easy control from the front As standard with control unit, flue gas fan, cleaning tools and boiler fill & drain tap Display of all relevant temperatures by the 2114 control unit Optimum system integration with automatically continuing operation, buffer cylinder primary pump with differential temperature control and buffer operation either in series or parallel Generously sized hopper 15/1 Logano S151 wood gasification boiler with 2114 control unit 15

16 3 Technical description Logano S151 function description General function characteristics The Logano S151 wood gasification boilers operate according the the down draught principle. They can accoodate split logs up to 50 cm in length and achieve continuous combustion times in excess of four hours on account of their hoppers that can hold up to 170 l. The excellent all-round thermal insulation keeps radiation losses very low. The boiler walls that are in contact with hot gases are robust thanks to their 6 wall thickness, and are designed for a long service life. Heat-up process Pull heat-up flap and open ( 16/1, Item 4) Open hopper door ( 16/2, Item 11); the flue gas fan ( 16/1, Item 7) starts automatically charge with suitable kindling and ignite Close hopper door After an adequate bed of embers has been formed, the hopper can be fully charged with split logs Push heat-up flap and close. Combustion changes over to down draught. The wood gases are degassed under full control in the higher hopper. The primary air required for this is directed by several apertures specifically towards the wood. The hot gases with added secondary combustion air ( 16/1, Item 9) are channelled via the jet stone to the secondary combustion zone in the fireclay-lined combustion chamber with flue gas reversal. The heat from the hot gases is transferred to the boiler water via the heating surface arranged below the combustion chamber. The hot gases flow towards the back and are drawn by the flue gas fan (Item 7) into the flue system. When the set maximum boiler temperature has been reached, the flue gas fan (Item 7) stops, and the output is substantially reduced. If the boiler water temperature falls (switching hysteresis), the flue gas fan starts again. The hopper door located at the front ( 16/2, Item 11) allows the boiler to be easily charged from the front. Cleaning apertures are arranged at the sides and top of the flue gas header (Item 12). A cleaning set is part of the standard delivery of the boiler. Ash and combustion residues can be brushed into the combustion chamber by removing the jet ( 16/1, Item 8). There, removal from the front through the combustion chamber door ( 16/2, Item 10) with the ash shovel provided is very easy. As standard, the Logano S151 is equipped with the 2114 control unit ( 16/1, Item 5) /1 Cross-section through the Logano S /2 Cross-section through the Logano S151 Key to diagram ( 16/1 and 16/2) 1 Combustion chamber 2 Primary ventilation air supply 3 Hopper 4 Heat-up flap control lever control unit 6 Flue path 7 Flue gas fan 8 Jet 9 Secondary air supply 10 Combustion chamber door 11 Hopper door 12 Flue gas header

17 Technical description Logano S231 special wood boiler Logano S231 equipment level General Output for detached houses and apartment buildings Predominant use as a sole heat generator in standalone wood combustion systems, but may also be used in dual-fuel boiler combinations High energy utilisation through low down combustion with generously sized secondary heating surface Excellent emission values through specific air routing and the TURBOAIR secondary combustion High operating and maintenance convenience Output 33 kw to 52 kw Fuel types Logs (up to 0.5 m) Coarse chippings (> 5 cm) "Treated" wood ( 27/1 and 28/1) "Chipboard" ( 28/1) 17/1 Logano S231 special wood boiler with integral SX control unit Special features Rated boiler output factory-set to 33/37/42/47/52 kw Integral SX control unit Standard flue gas fan Standard servomotor for regulating the primary air supply 2 sight glasses for assessing the secondary combustion channels 17

18 3 Technical description Logano S231 function description General function characteristics The Logano S231 special wood boiler ( 18/1) operates with side combustion. It can accoodate split logs up to 50 cm in length, and achieves continuous combustion times of up to six hours on account of its hopper that can hold approx. 180 l. Its all-round good thermal insulation keeps radiation losses very low. With a 10 thick boiler wall in the combined hopper and combustion chamber areas, the Logano S231 is extremely robust and designed for a long service life. The wood develops into gas under full control in the lower area of the combined hopper and combustion chamber. The primary air required for this process is supplied to the wood via air damper ( 18/1, Item 2) A B The hot gases are supplied from the side with a turbulent flow into the fireclay-lined vertical secondary combustion channels (Item 10), and rotated and mixed with the preheated secondary air via specifically arranged apertures. This reduces the CO emissions to a minimum. The turbulent combustion in the secondary combustion channels enables a homogeneous and even combustion reaction with a constant temperature of approx C. For this, additional tertiary apertures (Item 14) ensure an even combustion ratio between both secondary combustion channels /1 Cross-section through the Logano S231 As standard, the Logano S231 is equipped with a twostage flue gas fan (Item 8) and the SX user interface (Item 4) with differential temperature control of the buffer cylinder primary pump. The hopper door arranged at the top (Item 5) enables the boiler to be conveniently charged from above. 16 Key to diagram ( 18/1 and 18/2) 1 Air damper in the ash door (quarter air apertures) 2 Air damper for primary air A 3 Servomotor for primary air damper 4 SX control unit 5 Hopper door 6 Sight hole aperture 7 Cleaning door 8 Flue gas fan 9 Secondary heating surfaces 10 Secondary heating channels the secondary heating zone is separated from the hopper by a sheet steel wall as protection (not shown) 11 Cast iron insert grate 12 Ash box 13 Vertical grate 14 Air damper for secondary and tertiary air B 15 Combined hopper and combustion chamber 16 Ash door 15 18/2 Cross-section through the Logano S231, TURBOAIR general arrangement 18

19 Technical description Logano S241/SX241 special wood boiler Logano S241/SX241 equipment level General Output for detached houses and apartment buildings Predominant use as a sole heat generator in standalone wood combustion systems, but may also be used in dual-fuel boiler combinations S241 with base controller and SX241 with Ixtronic control unit and integral Lambda control Standard equipment level with safety heat exchanger for the connection of a thermally activated safety valve Lowest emissions, significantly below the permissible limits set by the German Iissions Act and currently applicable subsidy prograes High operating and maintenance convenience Highest energy utilisation through low down combustion with large secondary heating surface Output 23 kw to 30 kw 19/1 Logano S241/SX241 special wood boiler Fuel types Logs (up to 0.5 m) Special features Fireclay-lined combustion chamber with flue gas reversal for low emissions Minimum radiation losses through all-round good thermal insulation Standard two-stage flue gas fan Standard servomotors for regulating the primary and secondary air for optimum combustion Long service life through 6 thick boiler wall and 3 thick inserts made from heat-resistant sheet steel 19

20 3 Technical description Logano S241/SX241 function description General function characteristics The Logano S241 and SX241 special wood boilers ( 20/1), generally described as wood gasification boilers, operate in accordance with the down draught principle. They can accoodate split logs up to 50 cm in length and achieve continuous combustion times of up to six hours on account of their hoppers that can hold almost 130 l. The all-round thermal insulation with its thickness of 100 keeps radiation losses very low. With a 6 thick boiler wall and 3 thick replaceable inserts made from heatresistant sheet steel in the combustion chamber, the boiler is extremely robust and designed for a long service life. The wood gases are degassed under full control in the higher hopper ( 20/1, Item 9). The required primary air is directed specifically towards the wood through apertures in the hopper. The hot gases mixed with secondary air enter the fireclay-lined combustion chamber with flue gas reversal through the jet stone leading into the secondary combustion zone. The clever design and generously sized secondary heating surface ensure a long dwell time for the wood gases in the secondary combustion zone. This results for all output sizes in efficiency levels of over 90 % and consistently very low CO emissions. The Logano S241, equipped with a base controller, is fitted as standard with differential temperature control of the buffer cylinder primary pump. The Logano SX241 is also supplied with a Lambda probe and the Ixtronic control unit. In both versions, the two-stage flue gas fan as well as the primary and secondary combustion air are regulated separately from each other and thus ensure optimum combustion results. The hopper door arranged at the front enables the boiler to be conveniently charged from the front. Easily accessible cleaning apertures are arranged at the sides and top of the flue gas header (Item 5). These enable convenient cleaning of the combustion chamber and secondary heating surfaces. A cleaning brush is part of the standard delivery of the boiler /1 Cross-section through the Logano S241 Key to diagram 1 Large combustion chamber door 2 Servomotors for primary and secondary air 3 Hopper door 4 Control unit 5 Cleaning apertures 6 Mineral wool thermal insulation 7 Boiler wall 8 Inserts made from heat resistant sheet steel 9 Fireclay-lined hopper and combustion chamber

21 Technical description Dimensions and specification Logano S151 dimensions and specification L K VK ØD AA 2) H SWT 1) 1) H K L H VK RK H AA B H RK EL 1) Test port, thermally activated safety valve (fem. R6) 2) Flow and return, safety heat exchanger (male R5) 21/1 Logano S151 wood gasification boiler dimensions (in ) Boiler size Fuel Rated output kw Combustion output kw Length L L K Width B Height Height excl. control unit Transport Flue outlet Boiler flow Boiler return H H K Width Length Height D AA H A VK H VK RK H RK Inch Inch R R R R R R15 82 Wood R R R R R R15 70 Drain EL Inch R5 R5 R5 R5 R5 R5 Safety heat exchanger SWT Inch R5 R5 R5 R5 R5 R5 Weight kg Water capacity l Hopper capacity l Hopper depth Hopper door Width Height Split log length m Nominal combustion time h > 4 > 4 > 4 > 4 > 4 > 4 Flue gas temperature C Flue gas mass flow rate kg/s CO 2 content % Required draught Pa Permissible flow temperature 1) C Minimum return temperature C Permissible operating pressure bar /2 Logano S151 wood gasification boiler, dimensions and specification 1) Response point of the thermally activated safety valve; during operation no higher flow temperature than 90 C must be selected 21

22 3 Technical description Logano S231 dimensions and specification ØD AA L VSL 2) 225 VK H VK 1) 3) H H AA EL RSL ØD AA 210 RK H RK ) Test port (fem. R5) 2) Flow and return safety heat exchanger (fem. R6) 80 L K B 3) Test port, thermally activated safety valve (fem. R5) 22/1 Logano S231 special wood boiler dimensions (in ) Boiler size 40 Fuel Rated output 1) 22/2 Logano S231 special wood boiler, dimensions and specification 1) Setting a point output via air apertures (at the boiler) and draught stabiliser (at the chimney) 2) Where space is tight, the fan can be installed at a different point in the connection pipe ( 85/1) 3) Response point of the thermally activated safety valve; during operation no higher flow temperature than 90 C must be selected Wood kw 33 / 37 / 42 / 47 / 52 Combustion heat output 1) kw 40.1 / 45.0 / 51.3 / 57.1 / 63.2 Length L 2) L K Width B Height H Flue outlet Boiler flow Boiler return D AA H AA VK VSL H VK RK RSL H RK Inch Inch Inch Inch R5/4 R R5/4 R1 320 Drain EL Inch R1 Weight kg 740 Water capacity l 140 Hopper capacity l 180 Hopper Width Depth Height Hopper door Width Depth Split log length m 0.5 Nominal combustion time h 6.0 / 5.5 / 5.0 / 4.5 / 4.0 Flue gas temperature C 230 / 240 / 252 / 264 / 276 Flue gas mass flow rate kg/s / / / / CO 2 content % 13.3 / 13.6 / 13.9 / 14.3 / 14.6 Required draught Pa 19 / 21 / 23 / 25 / 27 Permissible flow temperature 3) C 95 Minimum return temperature C 40 Permissible operating pressure bar

23 Technical description Logano S241 dimensions and specification 646 H 1295 H AA ØD AA ) 3) VK H VK 1) EL RK H RK B L K L 612 1) Test port (fem. R5) 2) Flow and return safety heat exchanger (fem. R6) 3) Test port, thermally activated safety valve (fem. R5) 23/1 Logano S241 special wood boiler dimensions (in ) Boiler size Fuel Rated output kw Combustion output kw Length L L K Width B Height H Flue outlet D AA H AA Boiler flow Boiler return VK H VK RK H RK Inch Inch R R1 476 Wood R R R R1 476 Drain EL Inch R5 R5 R5 Weight kg Water capacity l Hopper capacity l Hopper Width Depth Height Charge aperture Width Height Split log length m Nominal combustion time h Flue gas temperature C Flue gas mass flow rate kg/s CO 2 content % Required draught Pa Max. permissible draught Pa Max. flow temperature 1) C Minimum return temperature C Permissible operating pressure bar /2 Logano S241 special wood boiler, dimensions and specification 1) Response point of the thermally activated safety valve; during operation no higher flow temperature than 90 C must be selected

24 3 Technical description Logano SX241 dimensions and specification ØD AA 2) H 1295 H AA 31 3) VK H VK ) EL RK H RK B L K L 1) Test port (fem. R5) 2) Flow and return safety heat exchanger (fem. R6) 3) Test port, thermally activated safety valve (fem. R5) 24/1 Logano SX241 special wood boiler dimensions (in ) Boiler size Fuel Rated output kw Combustion output kw Length L L K Width B Height H Flue outlet D AA H AA Boiler flow Boiler return VK H VK RK H RK Inch Inch R R1 476 Wood R R R R1 476 Drain EL Inch R5 R5 R5 Weight kg Water capacity l Hopper capacity l Hopper Width Depth Height Charge aperture Width Height Split log length m Nominal combustion time h Flue gas temperature C Flue gas mass flow rate kg/s CO 2 content % Required draught Pa Max. permissible draught Pa Max. flow temperature 1) C Minimum return temperature C Permissible operating pressure bar /2 Logano SX241 special wood boiler, dimensions and specification 1) Response point of the thermally activated safety valve; during operation no higher flow temperature than 90 C must be selected

25 Technical description Boiler parameters Pressure drop on the water side The pressure drop on the water side is the pressure differential between the boiler flow and return connections. It depends on the boiler size and the heating water flow rate c a b Key to diagram Δp H Pressure drop on the heating water side V H Heating water flow rate a Logano S151 b Logano S231 c Logano S241/SX241 Δp H [mbar] ,1 1,0 10,0 V H [m 3 /h] 25/1 Pressure drop on the water side of the Logano S151, S231 and S241/SX241 solid fuel boilers Boiler efficiency, fuel throughput and emission values Logano solid fuel boiler S151 Boiler size Rated output kw Efficiency % Fuel throughput kg/h CO mg/m 3 N Dust mg/m 3 N /2 Suary of the parameters for Logano S151 Logano solid fuel boiler S231 S241/SX241 1) Boiler size Rated output kw Efficiency % Fuel throughput kg/h CO mg/m 3 N Dust mg/m 3 N /3 Suary of the parameters for Logano S231 and S241/SX241 1) Subsidy possible according to the BAFA subsidy guidelines as part of the Germany government incentive scheme (MAP) (as of 11/2008) 25

26 4 Regulations and operating conditions 4 Regulations and operating conditions 4.1 Extracts from the regulations According to DIN EN 303-5, the boilers Logano S151, Logano S231 and Logano S241/SX241 are manually charged boilers for the combustion of natural firewood in log form. All are suitable for an operating pressure of 3 bar and are suitable for heating systems compliant with the requirements of DIN EN Observe the following regarding creation and operation of the system The technical building regulation rules Legal regulations Local regulations Installation, flue gas connection, coissioning, power supply as well as maintenance and repair work must only be carried out by qualified contractors. Approval Where required, inform your local flue gas inspector prior to installation. Regional approvals with regard to the flue system may be required. Maintenance According to paragraph 10 of the Energy Savings Order (EnEV) [Germany], the system must be serviced regularly, inspected at least every six months and cleaned as required. As part of this maintenance procedure, check the correct function of the entire system. We recoend system users to enter into a maintenance contract with their local heating contractor. Regular maintenance is a prerequisite for reliable and economical operation. DIN 4759 Connection to a coon chimney Information Chapter German Iissions Act One aim of the Iissions Act in Germany is the prevention of air pollution that is caused to a not inconsiderable degree by combustion systems. Acts, orders and administrative regulations describe in detail the requirements for systems that cause emissions. In this connection, the 1st BImSchV [Germany] applies to the Logano S151, Logano S231 and Logano S241/ SX241 solid fuel boilers st BImSchV Small combustion systems Combustion systems that do not require a permit in accordance with the German Iissions Act (BImSchV) fall into the application area of the First Order regarding the implementation of the Federal Iissions Act. Create and operate these systems in such a way that the requirements in Tab. 26/1 are met. Factors Fuels Flue gas plume in constant operation Rated output Requirement Heating the boilers only with fuel that is suitable in accordance with the manufacturer's instructions Lighter than grey value 1 according to the Ringelmann scale Heating only with the following fuels: 15 kw Anthracite/lignite/peat/natural logs > 15 kw Emission requirements according to Tab. 27/1 26/1 General requirements of the 1st BImSchV Emission requirements for manually charged combustion systems with rated boiler output in excess of 15 kw Manually charged combustion systems with rated boiler output in excess of 15 kw should generally be operated at full load. Install a buffer cylinder of adequate size in the system. If no adequate buffer cylinder is installed, carry out a measurement in the partial load range as well as the measurement under full load. 26

27 Regulations and operating conditions 4 Fuel Type of emission CO Anthracite/lignite/peat > kw: 4 g/m 3 > kw: 2 g/m 3 Natural wood > kw: 1 g/m 3 > 500 kw: 0.5 g/m 3 (respectively at 13 % O 2 ) "Treated wood": painted, lacquered, or coated wood, or plywood, chipboard, fibre board 1) kw: 0.8 g/m 3 > kw: 0.5 g/m 3 > 500 kw:0.3 g/m 3 (respectively at 13 % O 2 ) Dust > 15 kw: 0.15 g/m 3 (relative to 8 % O 2 ) 27/1 Emission requirements (extract) to 1st BImSchV 1) These types of fuel must only be used in combustion systems with a rated boiler output higher than 50 kw (Logano S231 with 52 kw) and only in wood treatment and processing plants, providing that no wood-preserving material is being applied or is contained in the wood, and no coatings are applied that contain halogenated compounds Rated output/fuel Testing emissions First test Annual test 15 kw / all permissible fuels > 15 kw / natural wood Yes > 15 kw / "treated wood" Yes Yes 27/2 Test cycles required by the emission regulations Note A revision of the 1st BImSchV (German Iissions Act) is intended. A significant strengthening of the limits and waiving of the 15 kw limit are currently expected. Please observe the relevant version of the BImSchV! 4.3 Operating requirements Required operating conditions The operating conditions listed in Tab. 27/3 are part of the warranty conditions for the Logano S151, Logano S231 and Logano S241/SX241solid fuel boilers. These operating conditions are ensured through a suitable hydraulic circuit and boiler circuit control. (Hydraulic connection page 56) Operating conditions for special applications on request. The requirements concerning the boiler water quality are also part of the warranty conditions. Solid fuel boiler Required operating conditions Boiler water Minimum boiler water Minimum return Buffer cylinder Logano Boiler size flow rate temperature temperature C C S151 15/20/25 > 70 Yes 65 30/35/40 > 70 Yes 65 S > 70 Yes 1) > 40 S241/SX241 23/27/30 > 60 Yes 2) > 40 27/3 Required operating conditions 1) The contents must be at least 25 l/kw; sizing Chapter 6 2) To qualify for the subsidy according to the BAFA subsidy guidelines as part of the German government incentive scheme (MAP) (as of 11/2008), the contents must be at least 55 l/kw (as of 06/2006); sizing Chapter 6 27

28 4 Regulations and operating conditions Fuels In general, only low fuming fuels must be used. The legally permitted (solid) fuels are listed in the 1st BImSchV. Alternative types of fuel (paper, cardboard etc.) are not permissible for systems subject to the regulations of the 1st BImSchV. The Buderus solid fuel boilers Logano S151, Logano S231 and Logano S241/SX241 are designed for burning logs, but also for alternative fuels in accordance with Tab. 28/1. Direct any enquiries regarding boilers and the combustion of alternative fuels to your local Buderus sales office ( back page). Solid fuel boiler Fuels Natural wood: Logs (split logs) Coarse chippings (> 5 cm) "Treated wood" 1) : painted, lacquered, Plywood 1) Chipboard 1) Logano Boiler size coated Fibre board 1) S151 15/20/25 30/35/40 S ) 2) S241/SX241 23/27/30 28/1 Suitable fuels Key to symbols: suitable; unsuitable 1) Fuel compliant with the 1st BImSchV; requirements page 26 2) Only for Logano S231 with a rated output of 52 kw Logano solid fuel boiler S151 S231 S241/SX241 Boiler size Max. split log length m /2 Maximum split log length 4.4 Corrosion protection in heating systems Combustion air Where combustion air is concerned ensure that it is not heavily contaminated with dust and contains no halogenated compounds. Otherwise there would be a risk that the combustion chamber and secondary heating surfaces would be damaged. Halogenated compounds are severely corrosive. These are contained in spray cans, thinners, cleaning & degreasing media and solvents. Design the combustion air supply so that, e.g., no exhaust air from chemical cleaners or paint shops is induced. Special requirements apply to the combustion air supply from within the installation room Additional protection against corrosion Damage through corrosion occurs if oxygen constantly enters the heating water. This is possible, e.g., in the negative pressure range, on account of an expansion vessel that is too small or via plastic pipes without an oxygen barrier. If the heating system cannot be realised as a sealed unvented system without permanent oxygen ingress, take additional corrosion protection measures. Suitable measures include softened water, oxygen binders or chemicals that form a coating on the material surface (e.g. in underfloor heating systems with plastic pipes). To prevent damage, chemical additives for heating water must be supplied with a suitability confirmation from their manufacturer. Where oxygen ingress cannot be prevented (e.g. in underfloor heating systems with pipework permeable to oxygen), system separation by means of a heat exchanger is recoended. 28

29 Sizing the wood boiler system 5 5 Sizing the wood boiler system 5.1 Basic principles The user of an advanced wood boiler system expects more than satisfactory system operation where efficiency and convenience are concerned. For wood boiler systems, different aspects need to be considered in terms of determining the boiler output than for advanced oil or gas boiler systems. Firstly this is the result of the manual and therefore not fully automatic combustion. Secondly it is caused by the inability to switch off combustion, which thirdly, today, means the obligatory use of a buffer cylinder. When sizing, take system and boiler-specific features into consideration. On the system side, note should be taken of modern operation with setback phases, and particularly the resulting output peak demand in the morning. Furthermore, consider the integration of the hydraulic framework conditions of the system resulting from the buffer cylinder integration. On the boiler side, take account of the time delay with which wood boilers deliver their output. This is reflected in the time it takes for an advanced wood boiler to deliver its full output from cold, i.e. 45 minutes is not unusual. Therefore, the following are fundamental recoendations: Load the buffer cylinder fully in the evening, so that the required heat for heating and reheating the building is available in the morning The non-automatic operation requires that the boiler output be determined according to different criteria than normally required for conventional boilers The integration of a buffer cylinder with associated modified hydraulic principles should be particularly designed for hydraulic balance in a system and/or a limiting of the maximum flow rate Two system types are identified for sizing considerations: Wood boilers that are backed up by another automatic heat source as required (dual-fuel boiler combination) Systems where the wood boiler is to be operated as the only heat source or where the operation should or must always be carried out without backup (stand-aline wood boiler systems) 5.2 Dual-fuel boiler combinations Where an automatic (second) heat source is available, and where the starting of that boiler is tolerated or is generally possible in cases where the wood boiler is not yet able to cover the heat demand, then the wood boiler will not need to be oversized. In this case, the variables boiler output and buffer cylinder volume should be appropriately matched. In some systems or when the wood boiler is used as backup, a certain undersizing of the wood boiler may be appropriate, since this system sizing case rarely occurs (e.g. 12 C), and the predominant operating point in our latitudes is between 0 C and +5 C. 29

30 5 Sizing the wood boiler system 5.3 Stand-alone wood boiler systems If the wood boiler is the only heat source or the system should/must be operated this way (e.g. where there is only one coon flue system), the question of oversizing arises. In older systems, this requires an initial practical assessment of the actual heat input. In many cases, an approximation of the minimum output demand of an older building can be obtained with reference to the MINERGIE calculation steps. Q min Q min = = Oil consumption l/a l/a Natural gas consumption m³/a m³/a 30/1 Formula for output demand according to MINERGIE Calculating sizes ( 30/1) Q min Minimum required output in kw The resulting required output frequently lies below the heat input calculated to DIN EN 12831, but has proven to be adequate in many practical cases. In case of unusual consumption patterns, considerable deviations from the estimated calculations can result. Furthermore, characteristics typical of wood boilers must be taken into account. E.g., each boiler design with its individual hopper size and rated boiler output delivers a certain combustion time that can be achieved with a full hopper. This means that a boiler with 3 h (or 6 h) combustion time needs to be charged 8 x (or 4 x) each day in order to be able to deliver its rated output for 24 h. However since there is no charging opportunity around the clock, apart from the necessary cleaning times, the heat deficits resulting from the lack of operation during operating times must be compensated. This is the additional boiler output or oversizing required on account of manual operation. e d c b a Full load combustion time of the wood boiler [h] Oversizing [%] 1 1,5 2 2,5 Factor f for boiler sizing 30/2 Determination of the oversizing necessary because of manual operation Key to diagram ( 30/2) a 2 charges per day b 3 charges per day c 4 charges per day d 5 charges per day e 6 charges per day The rated boiler output therefore results from the following: Q K = Q min f 30/3 Formula for rated boiler output Calculating sizes ( 30/3) f Boiler sizing factor Q K Rated boiler output in kw Q min Minimum required output in kw 30

31 Sizing the wood boiler system 5 Calculation example Given Older building, oil consumption of approx l Maximum 3 charges per day Calculation Approximate output demand in accordance with the formula 30/1: 4250 l Q min = = 17 kw 250 l/kw Result Boiler 1 with 6 h combustion time: Provide oversizing of approx. 33 %, factor f for boiler sizing = 1.33 ( 30/2) Output according to formula 30/3: Q K = 17 kw kw 23 kw boiler output required: Logano S (max. operating time 3 x 6 h = 18 h) Boiler 2 with 4 h combustion time: Provide oversizing of approx. 100 %, factor f for boiler sizing = 2 ( 30/2) Output according to formula 30/3: Q K = 17 kw 2 = 34 kw 34 kw boiler output required: Logano S (max. operating time 3 x 4 h = 12 h) By way of a reverse conclusion, the above considerations enable a determination of the maximum building heat input for this boiler type, given the specification of a required maximum number of charges ( 31/1). Logano solid fuel boiler S151 S231 S241/SX241 Boiler size Rated output kw Combustion time h Max. building heat input in stand-alone operation Max. 2 charges kw Max. 3 charges kw Max. 4 charges kw Max. 5 charges kw Max. 6 charges kw /1 Estimate of the maximum heat input based on the required number of charges 31

32 6 Sizing the buffer cylinder 6 Sizing the buffer cylinder 6.1 Necessity of the buffer cylinder The buffer cylinder enables combustion at the ideal operating point where energy utilisation and fuel consumption as well as emissions are concerned ( page 14). Heat that is currently not necessary for heating purposes is stored in the buffer cylinder. After the boiler charge has been completely used up, heat for the heating circuit is drawn exclusively from the buffer cylinder. Apart from the technical benefits, the use of a buffer cylinder also substantially improves the heating convenience, as the boiler needs fewer charges and fully automatic operation is possible. 6.2 Determining the size of the buffer cylinder In many quarters the theory is advanced that the buffer cylinder should be as large as possible. A different approach even calculates the size with fixed values that are related to the rated boiler output, e.g. 100 l/kw. Such arguments are supported by references to the 1st BImSchV. However, this only states: "(Wood combustion systems must be equipped) with an adequately sized thermal store". This statement clearly stipulates the need for factual and expert planning. The above methods in no way do justice to the need for adequate engineering thought. The aspects heat demand and economy would be completely overlooked by the above method. Other aspects, such as the required installation area and associated costs are pushed into the background by these approaches. The following therefore introduces two simple methods for sizing a buffer cylinder. The greater result from both methods should represent the minimum size of the buffer cylinder to be installed. Larger volumes would benefit the wood boiler technology and particularly the system convenience. These are, however, inevitably associated with higher costs, a greater installation area etc. System users who think (mostly) in terms of economy will accept the technically required and factually reasoned and calculable buffer cylinder size when making their purchasing decision. However, a more or less arbitrarily chosen buffer cylinder volume will frequently be a hindrance to wood combustion on account of the investment outlay involved. This too is a further reason in favour of sound technical planning. 32

33 Sizing the buffer cylinder Static method determining the size according to the amount of fuel the boiler can "handle" at any one time The background to this method of sizing is the assumption that the boiler with a full hopper/combustion chamber will be able to deliver its full available fuel energy to the buffer cylinder (if the system draws no heat). After converting units, applying approximate values for density and specific heat and by using empirical values, the buffer cylinder volume can be calculated with the following formula: V PU = 13, 5 Q K T B 33/1 Formula for buffer cylinder volume (rough estimate) Calculating sizes ( 33/1) V PU Buffer cylinder volume in l Q K Rated boiler output in kw T B Nominal combustion time in h This sizing methods allows for a quick estimate (without specific system knowledge) of a buffer cylinder volume for the selected wood boiler that would enable safe, largely economical operation of the wood boiler. If a different, smaller buffer cylinder volume is selected, heat draw-off or limited charging of the combustion chamber must be ensured. A larger buffer cylinder is beneficial for heating operation and safeguards an even higher level of system convenience. Calculation example Given Special wood boiler: Logano S Rated boiler output: 14.9 kw Nominal combustion time: approx. 4 h ( 21/2) Calculation Buffer cylinder volume according to formula 33/1: V PU = kw 4 h 805 l Result Buffer cylinder size to be selected 1000 l Logalux PR1000 ( page 41) DIN EN (April 1999) provides an extended formula for calculating a standard value for the absolute minimum buffer cylinder content:, = 15 T B Q K 1 0, V PU min 33/2 Formula for minimum buffer cylinder volume Calculating sizes ( 33/2) Q H Heat input of the building in kw Q Kmin Lowest adjustable boiler output in kw Q H Q Kmin The term in brackets ( 33/2) provides a kind of dynamic to the otherwise static formula. Consideration is give to the lowest possible boiler output in relation to the building heat input. This is based on the fact that in case of a ratio of minimum boiler output to heat input below 30 % there is no heating operation by the special wood boiler. If the boiler cannot reduce its output low enough, use a suitably sized buffer cylinder in line with the greater boiler minimum output. The suggested calculation in DIN EN is the first time a standard has created a basis for calculating buffer cylinder sizes. In the assessment of the calculation result, an important reference is made in the standard to the fact that the standard value refers to the absolute minimum buffer cylinder content. Standard values for buffer cylinder sizes Formula 33/1 allows the standard values for the sizes of buffer cylinders to be determined in conjunction with Buderus solid fuel boilers ( 33/3). Solid fuel boiler Standard values for buffer cylinder volume 1) Logano Boiler size l S S (1265 2) ) S241/SX (1485 2) ) (1650 2) ) 33/3 Standard values for buffer cylinder volume 1) 55 l/kw, likely requirements of the current draft of the 1st BImSchV (subject to modifications) 2) 55 l/kw according to the requirements of the German government subsidy prograe ( 27/3) 33

34 6 Sizing the buffer cylinder Dynamic method determining the size in accordance with heat demand and user habits The background to this sizing method is knowledge regarding the frequency distribution of the outside temperature During most of the heating season, only a fraction of the standard heat demand will be required. Select a system optimum for the most frequently occurring operating point. The following sizing method with the specified parameters is tailored to the residential sector with typical user profiles. 1) G t [Kd/a] ϑ A [ C] 1) Design point: most frequent operating point (approx. 45 % of the standard heat demand) 34/1 Main distribution of the daytime outside temperatures Diagram 34/2 clearly shows the approach to sizing: the excess output generated by the boiler during its operating time must be great enough to cover the residual (daytime) output demand. The buffer cylinder content, on the other hand, must be large enough to accept this residual output demand and be able to transfer it to the heating circuits after combustion stops. Key to diagram ( 34/1) G t Daily temperature figure Outside temperature ϑ A Q [kw] Q K ϕ Q N Excess = residual demand Key to diagram ( 34/2) f Beh Factor to consider the actual daytime heating period ϕ Factor to consider the design point ( 34/1); (3 C to 5 C outside temperature, corresponding to approx. 45 % of the standard heat demand) Q Output Q N Standard heat input to DIN EN Q K Rated boiler output t Time T Nominal combustion time in h (boiler operating time) 34/2 Sizing approach T t [h] f Beh 24 h 34

35 Sizing the buffer cylinder 6 After converting units, applying approximate values for density and specific heat and by using empirical values, the buffer cylinder volume can be calculated with the following formula: Q N 25, Q V PU = K 73 0, 4 ϑ Q N R 35/1 Formula for buffer cylinder volume (dynamic) Calculating sizes ( 35/1) V PU Buffer cylinder volume in l Q N Standard heat input to DIN EN in kw Q K Rated boiler output in kw ϑ R System design return temperature in C Conversion results in the following alternative process, e.g. if the system user defines specific maximum operating times for the boiler: 16 b V PU = , 4 ϑ Q N R 35/3 Formula for buffer cylinder volume (when defining the intended operating time) Calculating sizes ( 35/3) b Intended daily operating time of the boiler in h at the design point ( 34/1) With these design details, the required boiler output can be calculated according to the following formula: For these design details, the daily operation, i.e. the number of daily charges with wood at the design point ( 34/1) can be calculated: 64, Q K = Q b N 35/4 Formula for rated boiler output Q N T B Q K n = 64, /2 Formula for calculating the number of charges Calculating sizes ( 35/2) T B Nominal combustion time in h n Number of daily charges required This provides a simple formula for calculating the buffer cylinder size, which is determined only by the parameters heat demand, boiler output and design return temperature. For this, heat demand and design return temperature are system-dependent values. Consequently, any influence on the size of the buffer cylinder is only possible by varying the boiler (rated boiler output and nominal combustion time). The formulae correspond to one other. Calculation example Given Special wood boiler: Logano S Rated boiler output: 30 kw Heat input: 30 kw Design temperatures: 75/60 C Nominal combustion time: 4 h Calculation Buffer cylinder volume according to formula 35/1: 30 25, V PU = , = 2060ll Number of daily charges according to formula 35/2: 30 n = 64, = 1, Result Buffer cylinder size to be selected 2000 l 2 x Logalux PR1000 ( page 40) By charging the boiler once and subsequently recharging approximately half the hopper with firewood, the required daily heat demand in the design case, i.e. at approx. 3 C outside temperature, will be achieved. 35

36 6 Sizing the buffer cylinder Sizing the buffer cylinder primary pump To enable the buffer cylinder to be heated up as fully and evenly as possible (max. 90 C buffer cylinder temperature), the pump rate of the primary pump must be large enough to ensure the design temperature differential between flow and return is 5 K to 10 K. On account of the operating conditions, the buffer cylinder primary pump should be installed in the boiler return. The head is subject to the hydraulic pressure drop in the boiler circuit (pressure drop of the boiler, return temperature raising facility, profiles, pipework) Connecting the buffer cylinder Problems may arise if the buffer cylinder primary pump is incorrectly connected hydraulically. Such problems may be the following: Overlapping of pumps (flow rate and head) with excessive flow speeds, noise disturbance, poor control characteristics of valves and similar as a result Unintentional flow through heating circuits or DHW cylinders Unsatisfactory utilisation of the buffer cylinder Buffer cylinder as a low loss header We therefore recoend treating the buffer cylinder as a low loss header and connecting it accordingly ( 36/1). For this purpose, all Buderus buffer cylinders and combi cylinders are equipped with a corresponding number of connectors. The Logalux PR buffer cylinder provides a temperature-dependent return feed. This counteracts any possible stratification influence. VH RH 36/1 Connection with hydraulic separation via buffer cylinder Connection via tee As an alternative for buffer cylinders without specific return feed, the connection of the system return can be made via a tee at the lower buffer cylinder connector ( 36/2). This enables a counteraction to a possible stratification influence or dropping of the temperature level inside the buffer cylinder from the system return. For this it is important that the tee is provided iediately at the buffer cylinder connector, and that it corresponds to the connection dimensions to ensure an almost perfect hydraulic separation. VH RH Key to diagram ( 36/1 and 36/2) VH Heating circuit flow RH Heating circuit return 36/2 Coon connection via tee 36

37 Sizing the buffer cylinder Use of several buffer cylinders To achieve larger buffer cylinder volumes or for reasons of space or handling, it may be essential to use several buffer cylinders. When installing several buffer Information regarding parallel circuits Parallel circuits are recoended for two identical buffer cylinders. The circuit shown can be realised in the same way for further buffer cylinders. A changeover sensor for dual-fuel boiler combinations can be considered or implemented in all installed buffer cylinders and would have the same effect, since the temperature is evenly distributed in all buffer cylinders (Tichelmann connection!). The internal diameter of connection pipework with only partial flow must be adjusted in accordance with the flow rate (reduction). cylinders, a parallel connection according to the "Tichelmann system" is recoended to ensure an even load distribution. Logalux PR VL RL EK Logalux PR VL RL Buffer cylinder flow, subject to the respective hydraulics, to: Flow, heating circuits Return, oil/gas boiler Return, low loss header Buffer cylinder return, subject to the respective hydraulics, from: Return, heating circuits Diverter valve Cold water inlet EK 37/1 Parallel circuit for identical buffer cylinders Information regarding series circuits Series circuits are appropriate when different buffer cylinders (different volumes, different designs) are to be used, e.g. when combining the Logalux PR buffer cylinder with the Logalux PL.../2S combi cylinder. For this, the combi cylinder with integral DHW cylinder is to be heated with priority by the heat source, to achieve a high level of DHW convenience and a high DHW temperature ( 37/2). Connecting two identical buffer cylinders in series is possible, but is not recoended for energetic reasons, since the return from the heating circuits must initially always flow through the second and colder buffer. Parallel circuits are recoended for two identical buffer cylinders, i.e. Logalux PR ( 37/1). RL VL Logalux PR Logalux PL.../2S VL Buffer cylinder flow, subject to the respective hydraulics, to: Flow, heating circuits Return, oil/gas boiler Return, low loss header RL Buffer cylinder return, subject to the respective hydraulics, from: Return, heating circuits Diverter valve EK Cold water inlet 37/2 Circuits in series for different buffer cylinders EK 37

38 6 Sizing the buffer cylinder 6.3 Selection of the Buderus Logalux buffer cylinders Selection options Logalux PR.. buffer cylinder The Logalux PR buffer cylinders from Buderus are available in the sizes 500 l, 750 l and 1000 l. They are equipped with a special coon return channel for a temperature-dependent return feed. This achieves an optimum feed of the returns into the respective temperature level of the Logalux PR without influencing the stratification inside the cylinder (stratification cylinders). This results in significantly improved utilisation options for the heating energy stored in the buffer water. As thermal insulation, users can choose between the affordable 80 flexible foam insulation with a blue foil jacket (installation prior to the hydraulic connection) or a highly effective 120 flexible foam insulation with a rigid jacket made from PS (installation prior to or after the hydraulic connection). By connecting an external heat exchanger, solar energy can also be utilised. Logalux PL.. Thermosiphon buffer cylinder The Buderus Logalux PL buffer cylinders are offered in the sizes 750 l, 1000 l and 1500 l. They comprise a cylindrical steel container with integral Thermosiphon pipe and solar indirect coil for connection to a solar thermal system. The Thermosiphon pipe enables the cylinder to be heated from top to bottom (stratification cylinder). The easily fitted thermal insulation made from 100 flexible PU foam with external PS jacket reduces heat losses to a minimum. Suitable for up to 16 solar collectors Patented heat guiding pipe for stratified cylinder heating Up-draught-controlled gravity dampers Logalux STSK800 combi cylinder The combi cylinder fulfils two functions: Buffer cylinder for storing heating water DHW cylinder for DHW heating A thermo-glazed DHW cylinder (duplex jacket) is integrated into the upper section of the buffer cylinder. All DHW connections are routed from the top. Logalux P750 S combi cylinder The combi cylinder is designed for solar DHW heating, combined with solar central heating backup. The compact design results in favourable ratio between external surface area and volume, thereby minimising cylinder losses. The Logalux P750 S combi cylinder is fitted with a 100 thick, CFC-free thermal insulation jacket made from flexible PU foam. In addition, it offers the benefit of simplified hydraulics with few mechanical components. The combi cylinder has the following characteristics and special features Internal 160 l DHW cylinder with Buderus thermal glaze and magnesium anode as corrosion protection Generously sized smooth-tube internal coil for optimum utilisation of solar energy All DHW connections routed from above; all connections on the solar and heating side on the side of the cylinder Solar indirect coil in the heating water so there is no risk of scale deposits 38

39 Sizing the buffer cylinder 6 Logalux PL.../2S combi cylinder The combi cylinder fulfils two functions Buffer cylinder for storing heating water DHW cylinder for DHW heating A conical straight-through DHW cylinder is fitted inside the buffer cylinder. The solar indirect coil is integrated into a patented heat guiding pipe that is drawn over the entire cylinder height. This ensures the highest solar system efficiency, since the solar thermal system always heats the coldest medium first. Duo FWS.../2 combi cylinder The combi cylinder has the following characteristics and special features Corrugated internal stainless steel pipe (material W1.4404) for hygienic DHW heating High DHW convenience through corrugated pipe with large transfer area Generously sized smooth-tube internal coil for optimum utilisation of solar energy Solar indirect coil in the heating water so there is no risk of scale deposits Slimline version for easy handling All connections on the DHW and heating water side on the side of the cylinder Sensor terminal strip for variable sensor positioning A corrugated stainless steel pipe is wound internally onto a support structure. In its upper section, the corrugated pipe has a particularly large surface to achieve a high level of DHW convenience. The lower part is sized so that the cold water achieves high buffer cooling. This optimises the solar yield. 39

40 6 Sizing the buffer cylinder Logalux PR.. buffer cylinder, dimensions and specification D 80 / D 120 D SP VS1 H 80 / H 120 H VS1 1) VS2 M H VS2 1) VS3 H VS3 1) RS1 RS2 H RS1 H RS2 D SP D 80 / D 120 Side view Top view 1) Spring retainer for temperature sensor 40/1 Logalux PR.. buffer cylinder dimensions and connections (Dimensions in ) Key to diagram M Test port (female connection) Rp6 VS1 Cylinder flow, heating circuits VS2 Cylinder flow, solid fuel boiler VS3 Cylinder flow, solar RS1 Cylinder return, heating circuits RS2 Cylinder return, solid fuel boiler/solar Logalux buffer cylinder PR500 PR750 PR1000 Cylinder capacity l Diameter excl. thermal insulation Diameter incl. thermal insulation (80 ) Diameter incl. thermal insulation (120 ) Height incl. thermal insulation (80 ) Height incl. thermal insulation (120 ) Cylinder return Cylinder flow D SP D 80 D 120 H 80 H 120 RS1RS2 H RS1 H RS2 VS1VS3 H VS1 H VS2 H VS3 Inch Inch R R R R Max. operating pressure bar Max. operating temperature C Dry weight excl. thermal insulation kg /2 Logalux PR.. buffer cylinder dimensions and specification R R

41 Sizing the buffer cylinder Logalux PL.. Thermosiphon buffer cylinder, dimensions and specification D M D SP M1 M2 M3 M4 E VS2 VS3 M VS4 RS4 RS2 RS3 EL VS1 RS1 H H E H VS2 H VS3 H VS4 H RS4 H RS2 H RS3 H EL H VS1 H RS1 EL1 Top view M1M4 E RS1 VS1 EL1 RS1 VS1 RS1 VS1 20 Side view Logalux PL750, PL1500 View from below Logalux PL750 View from below Logalux PL /1 Logalux PL.. Thermosiphon buffer cylinder, dimensions and connections (Dimensions in ) Key to diagram M Test port (female connection) Rp6 M1 M4 Assignment subject to components, hydraulics and system control (the terminals M1 to M4 for temperature sensors are shown offset in the side view) VS1 Cylinder flow, solar thermal system RS1 Cylinder return, solar thermal system VS2VS4 1) Cylinder flow, heating water RS2RS4 1) Cylinder return, heating water 1) Utilisation subject to system components and hydraulics Logalux Thermosiphon buffer cylinder PL750 PL1000 PL1500 Cylinder capacity l Number of collectors Internal indirect coil capacity l Size of the indirect coil m Diameter excl. thermal insulation Diameter incl. thermal insulation D SP D Height incl. thermal insulation H Cylinder return RS1 RS2RS4 1) H RS1 H RS2 H RS3 H RS4 Inch Inch R6 R R6 R R6 R Cylinder flow Air vent valve Drain VS1 VS2VS4 1) H VS1 H VS2 H VS3 H VS4 E H E EL H EL H L1 41/2 Logalux PL.. Thermosiphon buffer cylinder, dimensions and specification 1) Utilisation subject to system components and hydraulics Inch Inch Inch Inch Inch R 6 R R R R R6 R R R R R6 R R R R6 Max. operating pressure (solar circuit/heating water) bar 8/3 8/3 8/3 Max. operating temperature (solar circuit/heating water) C 135/95 135/95 135/95 Weight kg

42 6 Sizing the buffer cylinder Logalux STSK800 combi cylinder, dimensions and specification D D SP H M1 VS1 VS X EZ/AW M2 M3 VS3 VS4 RS1 RS2 RS D SP D M EZ/AW EK X Side view Top view Detail 42/1 Logalux STSK800 combi cylinder, dimensions and connections (dim. in ) Key to diagram M Test port, welded sensor well with 19 internal diameter M1 M3 Assignment subject to system components, hydraulics andcontrol VS1VS4 1) Cylinder flow, heating water RS1RS3 1) Cylinder return, heating water 1) Utilisation subject to system components and hydraulics Logalux combi cylinder STSK800 Cylinder capacity, heating water Cylinder capacity DHW l l Standby heat loss 1) kwh/24 h 3.70 Diameter excl. thermal insulation D SP 800 Diameter incl. thermal insulation D 1000 Height H 1885 Cylinder return RS1RS3 Inch R14 Cylinder flow VS1VS4 Inch R14 DHW outlet AW Inch R6 Cold water inlet EK Inch R6 DHW circulation inlet EZ Inch R6 Max. operating pressure (heating water/dhw) bar 3/10 Max. operating temperature (heating water/dhw) C 95/95 Weight kg /2 Logalux STSK800 combi cylinder, dimensions and specification 1) According to DIN : DHW temperature 65 C, ambient temperature 20 C 42

43 Sizing the buffer cylinder Logalux P750 S combi cylinder, dimensions and specification D D SP M1 M2 M3 M4 M5 M6 M7 M8 M VS2 VS3 RS2 VS4 VS1 RS3 RS1 RS4/EL Top view AW/EZ M M1M8 EK EZ/AW MB1 550 View from below Side view 43/1 Logalux P750 S combi cylinder, dimensions and connections (dim. in ) Key to diagram M Test port (female connection) Rp6 M1 M8 Temperature test port; assignment subject to system components, hydraulics and control (the terminals M1 to M8 for temperaturesensors are shown offset in the side view) MB1 Test port, DHW VS1 Cylinder flow, solar thermal system VS2 Cylinder flow, solid fuel boiler VS3 VS4 RS1 RS2 RS3 RS4 Cylinder flow oil/gas/condensing boiler for DHW heating Cylinder flow, heating circuits Cylinder return, solar thermal system Cylinder return, oil/gas/condensing boiler for DHW heating Cylinder return, oil/gas boiler Cylinder return, heating circuits Logalux combi cylinder P750 S Cylinder capacity l 750 Number of collectors 46 Capacity, buffer section only l 400 DHW capacity l 160 Solar indirect coil capacity l 16.4 Constant output at 80/45/10 C 1) kw (l/h) 28 (688) Solar indirect coil size m Standby heat loss 2) kwh/24h 3.7 Performance factor 3) N L 3 Diameter excl. thermal insulation Diameter incl. thermal insulation 43/2 Logalux PL750 S combi cylinder, dimensions and specification 1) Heating water flow temperature/dhw outlet temperature/ cold water inlet temperature 2) According to DIN : DHW temperature 65 C, ambient temperature 20 C 3) According to DIN 4708 when heating the cylinder to 60 C and with a heating water flow temperature of 80 C D SP D DHW outlet AW Inch R6 Cold water inlet EK Inch R6 DHW circulation inlet EZ Inch R6 Drain EL Inch R14 Cylinder return RS1 RS2RS4 Inch Inch R1 R14 Cylinder flow VS1 VS2VS4 Max. operating pressure (solar indirect coil/heating water/dhw) bar 8/3/10 Max. operating temperature (heating water/dhw) C 95/95 Weight kg 262 Inch Inch R1 R14 43

44 6 Sizing the buffer cylinder Logalux PL.../2S combi cylinder, dimensions and specification D D SP 1920 M1 M2 M3 M4 M5 M6 M7 M8 EL2 VS2 VS3 M RS2 VS4 VS5 RS3 RS4 RS5/EL VS1 RS1/EL1 EK Top view AW/EZ EH M MB1 M1M8 EZ/AW Mg 550 View from below MB2 RS1 EK 640 VS1 EL2 Side view 44/1 Logalux PL.../2S combi cylinder, dimensions and connections (dim. in ) Key to diagram Mg Magnesium anode M Test port (female connection) Rp6 M1 M8 Temperature test port; assignment subject to system components, hydraulics and control (the terminals M1 to M8 for temperature sensors are shown offset in the side view) MB1 Test port, DHW MB2 Test port, solar VS1 Cylinder flow, solar thermal system RS1 Cylinder return, solar thermal system VS2VS5 1) Cylinder flow, heating water RS2RS5 1) Cylinder return, heating water 1) Utilisation subject to system components and hydraulics Logalux combi cylinder PL750/2S PL1000/2S Cylinder capacity l Solar indirect coil capacity l Solar indirect coil size m Constant output at 80/45/10 C 1) kw (l/h) 28 (688) 28 (688) Number of collectors Capacity, buffer section only l DHW capacity, overall/standby section l 300/ /150 Standby heat loss 2) kwh/24 h Performance factor 3) N L Diameter excl. thermal insulation Diameter incl. thermal insulation Cylinder return Cylinder flow D SP D RS1 RS2RS5 4) VS1 VS2VS5 4) Inch Inch Inch Inch R6 R14 R6 R14 DHW outlet AW Inch R6 R6 Cold water inlet EK Inch R1 R1 DHW circulation inlet EZ Inch R6 R6 Drain, central heating Drain, solar/dhw EL EL1EL2 44/2 Logalux PL.../2S combi cylinder, dimensions and specification 1) Heating water flow temperature/dhw outlet temperature/ cold water inlet temperature 2) According to DIN : DHW temperature 65 C, ambient temperature 20 C 3) According to DIN 4708 when heating the cylinder to 60 C and with a heating water flow temperature of 80 C 4) Utilisation subject to system components and hydraulics Inch Inch R14 R R6 R14 R6 R14 Max. operating pressure (solar indirect coil/heating water/dhw) bar 8/3/10 8/3/10 Max. operating temperature (heating water/dhw) C 95/95 95/95 Weight kg R14 R6 44

45 Sizing the buffer cylinder Duo FWS.../2 combi cylinder, dimensions and specification AW D VS2 VS3 A H AW A H VS2 H VS3 G A A VS4 H RS2 VS1 RS5 H VS4 H RS2 H VS1 H RS RS6 H RS6 EK RS3 RS1 RS4 H EK H RS3 H RS1 H RS4 Ø600 Side view incl. indirect coil and corrugated pipe HE Side view excl. indirect coil and corrugated pipe HE Side view excl. corrugated Top view excl. indirect coil 45/1 Duo FWS.../2 combi cylinder, dimensions and connections (dim. in ) Key to diagram VS1 Cylinder flow, solar thermal system VS2 Cylinder flow, pellet boiler/solid fuel boiler VS3 Cylinder flow oil/gas/condensing boiler for DHW heating VS4 Cylinder flow, heating circuits, pellet systems RS1 Cylinder return, solar thermal system RS2 RS3/RS6 RS4 RS5 Cylinder return, oil/gas/condensing boiler for DHW heating; cylinder flow, heating circuits; cylinder return, pellet boiler Cylinder return, heating circuits Cylinder return, solid fuel boiler Cylinder return, oil/gas/condensing boiler for DHW heating (alternative) Combi cylinder Duo FWS750/2 Duo FWS1000/2 Cylinder capacity l Solar indirect coil capacity/corrugated stainless steel pipe capacity (DHW) l 11/38 13/38 Solar indirect coil size/corrugated stainless steel pipe size m 2 2.2/7 2.7/7 Number of collectors Performance factor 1) for boiler output 25 kw/37 kw N L 3.2/ /4.2 Draw-off rate 2) Draw-off rate 10 l/min / 20 l/min l 255/ /260 Diameter excl. thermal insulation D Diameter incl. thermal insulation 80 /120 D W 910/ /1040 Height excl. thermal insulation H Height incl. thermal insulation 80 /120 H W 1985/ /2300 DHW outlet AW Inch R14 R14 H AW Cold water inlet EK Inch R14 R14 H EK Cylinder return RS1/RS2RS6 Inch G1/G15 G1/G15 H RS H RS H RS H RS H RS H RS Cylinder flow VS1/VS2VS4 Inch G1/G15 G1/G15 H VS H VS H VS H VS Max. operating pressure (heating water/dhw/solar circuit) bar 3/10/10 3/10/10 Max. operating temperature (heating water/dhw/solar circuit) C 95/95/110 95/95/110 Weight kg /2 Duo FWS.../2 combi cylinder, dimensions and specification 1) With reference to DIN 4708 T3 2) Without reheating, cylinder partially heated to 60 C, DHW temperature 45 C 45

46 6 Sizing the buffer cylinder 6.4 Freshwater station in connection with Buderus buffer cylinder Logalux FS and FS-Z freshwater stations Apart from DHW heating by means of mono-mode or dual-mode DHW cylinders or combi cylinders, the Logalux FS and Logalux FS-Z freshwater stations with integral DHW circulation pump are available. There are hygiene benefits from DHW heating according to the instantaneous water heating principle and the associated minimum storage. The station can be combined with the Logalux PR and Logalux PL buffer cylinders. It is also suitable for retrofitting existing buffer cylinders. An integral primary pump supplies heat to the station. Control is triggered by a water switch when DHW is drawn. The station flow is connected to the top of the buffer cylinder, the return at the bottom. The thermostatically controlled DHW temperature regulation is easy to operate. The version with the integral DHW circulation pump enables the pump to be controlled subject to temperature and optionally according to time or pulse. Special features 46/1 Logalux FS freshwater station Large heat exchanger for high draw-off rates with low system temperatures (nominal draw-off rate of 25 l/min at a buffer cylinder temperature of 60 C and a DHW temperature of 45 C) An integral thermostatically controlled DHW mixer safeguards a constant outlet temperature Mixer on the primary side to protect against scale build-up Logalux FS-Z with integral DHW circulation pump Shut-off valves on the DHW and the heating water side Thermal insulation shells and wall retainer are part of the standard delivery Easy service through flushing connections Possible pump replacement without the need to drain the system through integral shut-off valves (cold water shut-off tap on site, preventing the safety valve from being shut) Key to diagram ( 46/2) 1 Heat exchanger 2 Central heating pump 3 Water switch (hidden) 4 DHW mixer 5 Shut-off tap, flow 6 Flushing connections 7 DHW thermometer 8 DHW connection 9 Shut-off tap, DHW circulation (option) 10 DHW circulation pump (option) 11 Shut-off tap, return 12 Adjuster head for 3-way valve (max. flow temperature FS/FS-Z) 13 Control unit 46/2 Layout of the Logalux FS freshwater station 46