GB/T 3606-2025Domestic biogas stove (English PDF)

1 Scope

This document specifies the product classification, technical requirements, marking and packaging of domestic biogas stoves, and describes the test methods.

This document applies to domestic biogas stoves in which the nominal heat input of a single burner is not greater than 3.86 kW.

3 Terms and definitions

3.1 domestic biogas stove: a non-commercial burning appliance that uses biogas as fuel, supports the cooking vessel on its own pan support and heats the vessel directly with the flame of the burning biogas. Note: in what follows a domestic biogas stove is called simply a stove.

3.2 embedded biogas stove: a biogas stove set into a cooking worktop. Note: in what follows an embedded biogas stove is called simply a built-in stove.

3.3 standard conditions: the state of dry biogas at a temperature of 15 degrees Celsius and an absolute pressure of 101.3 kPa.

3.4 net Wobbe number: the ratio of the net calorific value of the biogas to the square root of its relative density.

3.5 nominal heat input, nominal heat flow: the design value of the heat input of the stove declared by the manufacturer, at the nominal biogas supply pressure and using test biogas at standard conditions.

3.6 actual heat input, actual heat flow: the product of the net calorific value of the test gas and the measured biogas flow under test conditions.

3.7 biogas supply pressure: the relative static pressure measured at the biogas inlet connection of the stove while the stove is running.

3.8 nominal biogas pressure: the design value of the biogas supply pressure fixed by the manufacturer from the actual delivery pressure of the biogas pipeline and the requirements of the standard.

3.9 burner: the device that makes the biogas burn stably.

3.10 main burner: the burner used for cooking or for preparing hot water when the stove is running.

3.11 permanent ignition burner: the small burner that lights the main burner with its flame and does not go out while the stove is working or on standby.

4 Product classification

4.1.1 By number of burners, stoves are divided into single burner stoves and double burner stoves.

4.1.2 By structural form, they are divided into table stoves and built-in stoves.

4.2 The model designation is made up of the product code, the number of burners, the structural form, the ignition method and the manufacturer's own serial number. The product code is the capital letters HZZ. The number of burners is given in Arabic numerals, 1 for a single burner stove and 2 for a double burner stove. The structural form is given by a capital letter, T for a table stove and Q for a built-in stove. The ignition method is given by a capital letter, D for electronic ignition and M for pulse ignition. The manufacturer's own serial number is given in letters or Arabic numerals. Thus HZZ2-TD-AB denotes a domestic biogas double burner table stove with electronic ignition.

5 Technical requirements

5.1.1 The nominal supply pressure at the stove inlet is 0.8 kPa, generally for a single burner stove, or 1.6 kPa, generally for a double burner stove.

5.1.2 For a stove used at high altitude, the effect of altitude on the actual heat input shall be taken into account.

5.1.3 An automatic pressure stabiliser should be fitted upstream of the stove.

5.1.4 A stove used on a centralised biogas supply shall be fitted with a flame failure device, the technical requirements following GB 16410-2020.

5.1.5 The biogas source shall be dewatered and desulphurized before use; the quality shall satisfy a methane content greater than 50 percent and a hydrogen sulfide content less than 20 mg per cubic metre.

5.2.1 The gas tightness of the stove shall satisfy the following: from the biogas inlet to the biogas valve, the leakage at a pressure of 4.2 kPa shall be not greater than 0.07 L per hour; for an automatic control valve at 4.2 kPa, not greater than 0.55 L per hour; and with the burner lit at 1.5 times the nominal pressure, there shall be no leakage anywhere from the biogas inlet to the burner ports.

5.2.2 The heat input shall satisfy the following: the deviation between the corrected actual heat input of each burner and the nominal heat input shall be within plus or minus 10 percent; the ratio of the total corrected actual heat input to the sum of the corrected actual heat inputs of the individual burners shall be not less than 90 percent; and a double burner stove shall have one main burner whose corrected actual heat input is not less than 3.26 kW.

5.2.3 The combustion behaviour shall comply with Table 1, which fixes, item by item: flame transfer, ignition within 4 s with no explosive ignition; lightback, none; combustion noise, not greater than 65 dB(A); extinction noise, not greater than 85 dB(A); the CO concentration in the dry flue gas at a theoretical air factor of one, expressed as a volume fraction, not greater than 0.05 percent for an indoor type stove and not greater than 0.08 percent for an outdoor type; yellow flame contact, the electrode shall not be in frequent contact with a yellow flame; the combustion stability of the permanent ignition burner, no extinction and no lightback; and the combustion stability when an oversize pan is used, again no extinction and no lightback. A note refers the nitrogen oxide content of the flue gas and its test method to Annex A.

5.2.4 The temperature rise shall not exceed the values of Table 2, which fixes, for the parts the hand must touch during operation, 35 degrees Celsius for metal and coated metal and 45 degrees Celsius for non-metallic materials; 20 degrees Celsius for the case of a dry battery; 20 degrees Celsius for the hose connector; 50 degrees Celsius for the valve body; 50 degrees Celsius for the igniter case; and 100 degrees Celsius for the wooden wall at the side and rear of the stove and the surface of the wooden table beneath it, both when the lower limit pan is used and when the oversize pan is used.

5.2.5 The electric ignition device shall light the burner at least nine times out of ten, with no explosive ignition.

5.2.6 The thermal efficiency shall be not less than 55 percent for a table stove and not less than 50 percent for a built-in stove.

5.2.7 The durability shall comply with Table 3, which requires that the biogas plug valve, after 30 000 operations, still passes the gas tightness test and remains usable, and that the electric ignition device, after 30 000 operations, still ignites satisfactorily and remains usable.

5.2.8 After the vibration test on the packed stove, the gas tightness shall still comply with 5.2.1.

5.2.9 After the drop test on the packed stove by the method of GB/T 1019-2008, the gas tightness shall still comply with 5.2.1.

5.2.10 After the stacking compression test on the packed stove by the method of GB/T 1019-2008, the difference between the height of the package after the test and its height before shall be less than 1 cm per metre.

5.3.1.1 The parts of the stove shall be safe and durable, and shall not break or deform in a way that affects use during transport or in normal operation.

5.3.1.2 The stove shall be stable enough in normal use not to slide or topple over.

5.3.1.3 The stove as a whole shall not overturn when tilted 15 degrees in any direction, and no part shall come off.

5.3.1.4 The state of the burner flame shall be easy to observe.

5.3.1.5 The ends of parts the hand may touch in use and cleaning shall be smooth.

5.3.1.6 The parts shall be connected firmly and reliably and be easy to service; they shall be easy to take apart and put back with ordinary tools.

5.3.1.8 The biogas tubes shall satisfy the following: the tubes, including that of the ignition burner, shall be placed where they will not overheat and will not corrode; the internal diameter of the ignition burner tube shall be not less than 2 mm; where the tubes are joined by welding, the construction shall ensure the seal; the hose connector of the stove shall be one of the two forms shown in Figure 2 of GB 16410-2020, of 9.5 mm or 13 mm diameter; and the connection between the hose and the connector shall be secured safely.

5.3.1.9 The valve and the air shutter shall be easy to adjust and operate and shall not loosen once set, and the open and closed positions of the valve shall be clearly marked with their direction.

5.3.1.10 The knobs shall be shaped so that in normal use the operator's hand cannot reach parts whose temperature rise is too high.

5.3.1.11 Asbestos shall not be used in the construction of the stove.

5.3.2.1 A double burner stove shall have at least one burner whose pan support suits a round-bottomed pan, on which the pan sits steadily in normal operation without hindering use.

5.3.2.2 The pan supports shall satisfy the following: they shall be steady and firm with pans of different types, one burner shall take a flat-bottomed pan 100 mm in diameter, movable pan supports shall be easy to adjust and change, and a round-bottomed pan shall not affect normal combustion; and the supports shall be strong enough not to hinder normal use, showing no deformation or damage under a static load of 98.1 N.

5.3.2.3 The spill tray shall have enough capacity to catch liquid that boils over.

5.3.2.4 Where a non-metallic material is used for the top panel, the fragments shall not fly and the cooking vessel shall not overturn if the panel breaks.

5.3.2.5 In the top panel load test the deflection at any point of the panel shall be not greater than 1 mm.

5.3.2.6 A built-in stove shall further satisfy the following: the base plate shall be of a form easy to clean with ordinary tools; the base plate shall be of corrosion resistant material or shall be protected against corrosion; the joint between the built-in part and the worktop shall be a closed construction; the burner caps, the spill tray and similar parts shall be of a form that resists spillage, so that liquid does not readily run onto the base plate; there shall be an air inlet for combustion air, placed and shaped so as not to affect combustion performance; and the top panel shall be of a material resistant to high temperature and to deflection, the thermal deflection at any point being not greater than 1 mm.

5.4.1 The materials shall withstand the temperatures of normal use; metal parts, other than those of corrosion resistant material, shall be electroplated, painted, enamelled or given some other suitable protective surface treatment.

5.4.2 The biogas tubes shall be of a material resistant to more than 350 degrees Celsius and the ignition burner tubes of a material resistant to more than 500 degrees Celsius.

5.4.3 The plug valve shall be of a material resistant to more than 350 degrees Celsius; the injector shall be of a material resistant to more than 500 degrees Celsius and the injector holder of one resistant to more than 350 degrees Celsius; the air regulator, that is the air shutter, shall be of a material resistant to more than 500 degrees Celsius.

5.4.7 The burner port area shall be of a material resistant to more than 700 degrees Celsius. For every part between the injector outlet and the burner ports, a lightback test of 15 min carried out by the burner overheating test method shall leave the burner with no deformation that affects performance.

5.4.8 The pan supports shall be of a material resistant to more than 700 degrees Celsius, and the spill tray of a material resistant to more than 500 degrees Celsius.

6 Test methods

6.1.1 The room temperature shall be 20 degrees Celsius plus or minus 5 degrees Celsius, and its fluctuation during each test shall be less than 5 degrees Celsius. Note: room temperature is measured by fixing the sensing part of a thermometer at about the height of the top of the stove at each of three points 1 m in front of, to the left of and to the right of the stove, and taking the average of the three.

6.1.2 Ventilation shall be good; the CO content of the room air shall be less than 0.002 percent and the CO2 content less than 0.2 percent, and during the test the air speed 1 m from the stove shall be less than 0.1 m per second.

6.1.3 The atmospheric pressure shall be 86 kPa to 106 kPa and the relative humidity less than 80 percent.

6.2.1 The synthetic test biogas is made up from methane of purity not less than 99.9 percent and carbon dioxide of purity not less than 99.9 percent, with a net calorific value of 21 MJ per cubic metre plus or minus 1 MJ per cubic metre; during the test the net Wobbe number of the biogas shall vary by less than 2 percent. The static pressure when the stove is not running shall be not more than 1.25 times the supply pressure when it is running.

6.2.2 The test supply pressures are given in Table 4: for a double burner stove, a maximum test pressure of 2 400 Pa, a nominal supply pressure of 1 600 Pa and a minimum test pressure of 800 Pa; for a single burner stove, 1 200 Pa, 800 Pa and 400 Pa respectively.

6.2.3 During the test the pressure shall fluctuate by less than plus or minus 10 Pa.

6.3 Table 5 lists the instruments, their ranges and their accuracy or smallest division: thermometers for room and gas temperature over 0 to 50 degrees Celsius, reading to 0.5 degrees Celsius for gas and 1 degree Celsius for room air; a hygrometer over 10 to 98 percent to plus or minus 5 percent; a barometer over 81 to 107 kPa to 0.1 kPa; a U-tube gauge for biogas pressure above 5 000 Pa to 10 Pa; a stopwatch to 0.1 s; a gas meter to 0.1 L; a gas relative density meter to plus or minus 2 percent; a gas leak detector; a sound level meter over 40 to 120 dB to 1 dB; a chromatograph or absorption type gas analyser for gas composition; a calorimeter for calorific value; a CO analyser over 0 to 0.2 percent to 0.001 percent; a CO2 analyser over 0 to 15 percent to 0.01 percent; an oxygen analyser over 0 to 21 percent to 0.01 percent; a thermometer for water temperature over 0 to 100 degrees Celsius to 0.2 degrees Celsius; thermocouples and a thermoelectric thermometer for surface temperature over 0 to 300 degrees Celsius to 1 degree Celsius; a balance over 0 to 15 kg to 5 g; and a thickness gauge to 0.01 mm.

6.4 Table 6 lists the test equipment: a gas mixing rig holding the Wobbe number to plus or minus 2 percent; a biogas consumption rig with pressure regulator, flow meter, hygrometer, thermometer, pressure gauge and tee for the heat input measurement; the test pans of Table 8 for the thermal efficiency measurement; a leak detector rig for the gas tightness test; durability rigs for the gas valve and for the ignition and control devices; a thermostatic cabinet from 25 to 750 degrees Celsius for the heat resistance test on structural parts; and a vibration table with a frequency of 10 Hz and a total amplitude of 5 mm, vertically and horizontally.

6.5 The stove shall be tested in the prescribed installed and operating condition and, apart from what the individual performance tests provide, the following shall be met: the combustion air shall be adjusted to give the best flame and the air shutter then fixed, and it shall not be adjusted again during the performance tests; the aluminium lower limit pan and the water charge selected from Table 8 shall be used, water being topped up when the level falls below half; in the rice pot test the water shall be filled to the maximum quantity of rice and topped up when the level falls below half; and the distance from the stove to a wall or other obstruction shall be more than 150 mm.

6.6 For gas tightness from the biogas inlet to the biogas valve, air is admitted at 4.2 kPa with the valve under test closed, and the leak detector is connected at the inlet to measure the leakage. For gas tightness from the inlet to the burner ports, all burners are lit at the maximum test pressure and every part between the inlet and the burner ports is checked with soap solution or leak detection fluid for signs of leakage.

6.7.1 The actual heat input is measured at the nominal supply pressure, with the pressure gauge, the flow meter and the stove connected as shown in Figure 4 of GB 16410-2020 and the gas path upstream of the stove fully open before lighting. To measure the heat input of a single burner, only that burner is lit and the burners are checked one by one; to measure the total heat input of the stove, all burners are lit together. Between 15 min and 20 min after lighting, the biogas flow is measured with the gas meter over one or more complete revolutions of the pointer and over not less than 1 min, the measurement being repeated at least twice with a reading error of less than 2 percent, and the average of the two flows taken. The actual heat input is then calculated by formula (1), in which the flow is the measured biogas flow in cubic metres per hour, the calorific value is the net calorific value of the test biogas at standard conditions in megajoules per cubic metre, the gas temperature is that inside the flow meter in degrees Celsius, the atmospheric pressure and the relative static pressure inside the flow meter are in kilopascals, and the last term is the saturated water vapour pressure at the gas temperature in kilopascals, this value being corrected by the relative humidity of the test biogas where a dry flow meter is used.

6.7.2 The corrected actual heat input is calculated by formula (2), whose symbols add to those of formula (1) the relative density of the dry test biogas at standard conditions, the relative density of the dry design biogas at standard conditions, the nominal biogas supply pressure used in the design, the measured relative static pressure upstream of the stove, and the constant 0.622, which is the relative density of water vapour treated as an ideal gas.

6.7.3 The accuracy of the nominal heat input is calculated by formula (3) as the difference between the corrected actual heat input and the nominal heat input divided by the nominal heat input, expressed as a percentage.

6.7.4 The ratio of the total corrected actual heat input to the sum of the corrected actual heat inputs of the individual burners is calculated by formula (4).

6.8.1 The test pressures for the combustion behaviour tests are given in Table 7, for the double burner stove and the single burner stove respectively: flame transfer at 1 600 Pa and 800 Pa; flame lift at 2 400 Pa and 1 200 Pa; extinction at 2 400 Pa and 800 Pa, and at 1 200 Pa and 400 Pa; flame uniformity at 1 600 Pa and 800 Pa; lightback at 800 Pa and 400 Pa; the permanent ignition burner at 800 Pa and 400 Pa; combustion noise at 2 400 Pa and 1 200 Pa; extinction noise at 1 600 Pa and 800 Pa; CO at 1 600 Pa and 800 Pa; black smoke at 2 400 Pa and 1 200 Pa; yellow flame contact at 2 400 Pa and 1 200 Pa; and combustion stability with an oversize pan at 2 400 Pa and 1 200 Pa.

6.8.2.1 Flame transfer: for a stove with gas rate adjustment the test is made only at the maximum setting; one port of the main burner is lit from cold and the time for the flame to travel to all the ports is recorded, and it is observed whether explosive ignition occurs.

6.8.2.2 Flame lift: the main burner is lit from cold and, if after 15 s more than a third of the ports show flame lift, flame lift is recorded.

6.8.2.3 Extinction: 15 s after the main burner is lit, it is observed whether every port carries a flame.

6.8.2.4 Flame uniformity: 20 min after the main burner is lit, it is observed whether the flame is clear and even.

6.8.2.5 Lightback: 20 min after the main burner is lit, it is observed whether lightback occurs.

6.8.2.6 Combustion noise: all burners are lit and after 15 min the test is made at the points shown in Figure 5 of GB 16410-2020, using a sound level meter on the A weighting and fast response; the background noise shall be less than 40 dB or at least 10 dB below the measured noise of the stove, failing which a correction is made according to Annex A of GB/T 3768-2017.

6.8.2.7 Extinction noise: after the stove has run for 15 min the gas valve is shut quickly and the test is made at the three points shown in Figure 5 of GB 16410-2020, on the same weighting and response and with the same background requirement; 5 dB is added to the largest measured value to give the extinction noise.

6.8.2.8 CO in the dry flue gas: with the stove in the condition of 6.5, the flue gas sampler and the sampling position follow Figure 6a) and Figure 6b) of GB 16410-2020; the CO2 concentration of the room air in its dry state is measured; 15 min after the stove is lit a sample is taken and the CO and CO2 contents of the dry flue gas measured; and the concentration is calculated by formula (5), whose terms are the measured CO concentration of the dry flue gas sample, the calculated theoretical CO2 concentration of the dry flue gas, the measured CO2 concentration of the sample and the measured CO2 concentration of the dry room air, all as volume fractions.

6.8.2.9 Black smoke: from lighting the main burner from cold until the flame is steady, a clean pan or a bright metal plate is placed on the stove and it is observed whether black smoke appears; the test is repeated once after the stove has run for 20 min.

6.8.2.10 Yellow flame contact: from lighting the main burner from cold, after 15 min it is observed whether a yellow flame is present; if it is, and if within any period of 1 min the electrode is in continuous contact with the yellow flame for more than 30 s, yellow flame contact is recorded.

6.8.2.11 Combustion stability of the permanent ignition burner: on a stove that has one, it is lit and after 15 min it is observed whether it goes out or lights back; then, with the gas valve fully open, the main burner is lit repeatedly and it is checked whether the permanent ignition burner goes out or lights back as the main burner is lit and extinguished.

6.8.2.12 Combustion stability with an oversize pan: a pan 4 cm larger in diameter than the lower limit test pan of Table 8 is used; the burners are lit one by one with the gas valve fully open and it is checked visually whether there is black smoke and whether combustion is stable.

6.9.1 In the general temperature rise test the stove is run at the maximum test pressure in an ambient temperature of 20 degrees Celsius plus or minus 5 degrees Celsius, in the condition of 6.5, with the temperature rise rig of Figure 9 of GB 16410-2020 and the stove at the distance from the measuring board given in Figure 10 of that standard. All burners are lit and their valves opened fully; the stove starts at maximum load and, as soon as the water boils, is turned down at once to the minimum load that keeps a gentle boil, and held there to the end of the test. Once the temperature rise at the measuring points is steady, the heating period being at most 1 h, the rise is measured and recorded with a thermoelectric thermometer or thermocouples embedded in the board at the parts the hand must touch in operation, the dry battery case, the hose connector, the valve body, the igniter case, the biogas regulator case, and the wooden wall at the side and rear and the wooden table surface beneath the stove.

6.9.2 The oversize pan temperature rise test is made in the same way but with a pan 4 cm larger in diameter than the lower limit test pan of Table 8, the wooden wall at the side and rear and the wooden table surface beneath the stove being the parts measured.

6.10 The electric ignition device is tested at the maximum and the minimum test pressure, the supply voltage of a dry battery igniter being adjusted to 70 percent of its nominal value. Several preliminary ignitions are made first; each ignition is made with the burner near room temperature. For a rotary igniter one turn counts as one ignition and each is made within 0.5 s to 1 s; for a continuous discharge igniter on a direct current supply, holding the ignition position for 2 s counts as one. Ignition is repeated ten times and the number of lightings and any explosive ignition recorded.

6.11 The thermal efficiency is measured at the nominal supply pressure, the stove being connected as in Figure 4a) of GB 16410-2020 with the pressure tube made as in Figure 4b) and the stirrer as in Figure 12, or another device that mixes the water evenly. The actual heat input is calculated by formula (1), and the upper and lower limit pans and the water charge are taken from Table 8. The burner is lit and the supply pressure adjusted to its nominal value; once combustion is steady the pan is set on, the initial water temperature being room temperature plus 5 degrees Celsius and the final temperature the initial temperature plus 30 degrees Celsius. Stirring begins 5 degrees Celsius below the initial temperature, gas consumption is metered from the initial temperature, stirring begins again 25 degrees Celsius above it, and at 30 degrees Celsius above it the gas is shut off and all parameters recorded. The actual thermal efficiency is calculated by formula (6), whose terms are the equivalent water charge, being the water added plus 0.213 times the mass of the aluminium pan with its lid and stirrer, the specific heat capacity of water, the final and initial water temperatures, the measured biogas consumption, the net calorific value at 15 degrees Celsius and 101.3 kPa, the gas temperature in the meter, the atmospheric pressure, the relative static pressure in the meter and the saturated water vapour pressure at the gas temperature. Two or more tests are made under the same conditions; where two consecutive efficiencies differ by less than 1 percent of their average, the average is taken as the actual thermal efficiency, and otherwise the test is repeated until it is satisfied. Once the actual efficiencies with the upper and the lower limit pans are known, the efficiency of the burner is calculated by formula (7) from those two efficiencies and the heat intensity at the pan bottom in each case, the heat intensity being the actual heat input in watts divided by the projected area of the test pan in square centimetres.

6.12 In the durability test the biogas plug valve and the electric ignition device are each worked with air at the nominal biogas supply pressure, either detached from the stove or fitted to it, at 5 to 20 operations per minute; after 30 000 operations the valve is subjected to the gas tightness and operating tests and the ignition device to the ignition test.

6.13 For the vibration test the stove is tied up as for transport, placed level on the vibration machine and vibrated at 10 Hz with a total amplitude of 5 mm for 30 min vertically and 30 min horizontally, after which the gas tightness test is made.

6.14 The drop test follows 5.9 of GB/T 1019-2008, the drop height being taken from distribution condition one of Table 3 of that standard, and the biogas tightness test follows the drop.

6.15 The package compression test follows GB/T 4857.3.

6.16.2 In the tilt and overturn test the stove is placed level on the test bench and tilted gradually to 15 degrees from the horizontal; it is observed whether it overturns and whether the parts carrying the flame move or come off.

6.16.3 In the top panel and pan support load test the stove is placed level on a firm surface and a static load of 98.1 N is applied for 5 min at the centre of the pan support, after which the deflection at any point of the panel and any deformation or damage to the pan support are checked.

6.16.4 For the requirement that the burner port area be of a material resistant to more than 700 degrees Celsius, the part forming the ports, taken out as a unit that comes apart easily, is measured and its port area calculated; it is then held in a thermostatic cabinet set to 700 degrees Celsius for 2 h, taken out and allowed to cool to room temperature in air, and measured again; the change in port area before and after the test shall be within plus or minus 10 percent, and anything beyond that range fails.

6.17 The material tests are made by inspection against 5.4, the burner wall thickness being measured with a thickness gauge; the thermal shock test follows 6.10 of GB 16410-2020 and the gravity impact test follows 6.11 of that standard.

7 Marking and packaging

7.1.1 Every stove shall carry a nameplate in a suitable position giving the product name and model, the nominal biogas supply pressure, the nominal heat input, the name of the manufacturer, and the year and month of manufacture or a code for it.

7.1.2 The marking on the packing case shall include the standard applied; the product name and model; the name and trademark of the manufacturer; the year and month of manufacture or a works serial number, which shall carry the year and month; the cut-out dimensions for building in, using the codes of Annex B, or the actual width, depth and corner radius where the built-in stove is not one of the recommended sizes; the mass in kilograms; the outside dimensions of the packing case in millimetres, length by width by height; the packaging, storage and transport pictorial marks, whose wording or symbols shall comply with GB/T 191; and the works address and contact details.

7.2.1 The packaging shall be safe, firm and presentable, and the packing case shall carry the packaging, storage and transport pictorial marks complying with GB/T 191.

7.2.2 The packing case shall contain a list of accessories, a certificate of conformity, a warranty card and the installation and operating instructions.

7.3 Every stove shall leave the works with installation and operating instructions covering the outside dimensions of the product and how it is installed; the operation of ignition, extinction and flame adjustment, with the method of adjusting the air shutter where there is one; safety points concerning biogas, ventilation, fire, scalding and keeping children away; points on cleaning and servicing; the works address and contact details; the cut-out dimensions and the method of fixing for a built-in stove; a warning that the cabinet housing a built-in stove must have an opening to the outside air meeting the ventilation requirement, since otherwise leaking biogas can collect and explode; all the information on the nameplate, where the marking is not visible once the built-in stove is installed; a warning that the stove becomes hot in use and that contact with heated parts should be avoided, metal objects such as knives, forks, spoons and lids not being left on the stove top because they may become hot; and the standard applied.

A Annex A (informative) Nitrogen oxide content of the combustion flue gas of domestic biogas stoves

A.1 The limiting concentration of nitrogen oxides in the combustion flue gas of a domestic biogas stove is not greater than 0.015 percent.

A.2 A chemiluminescence, electrochemical or infrared flue gas analyser is used, with a range of 0 to 0.05 percent and a smallest division of 0.001 percent.

A.3 and A.4 The test is made at the nominal test biogas supply pressure with the stove in the condition of 6.5.

A.5 After the stove has run for 15 min a flue gas sample is taken and its nitrogen oxide content measured; the oxygen content of the sample shall be not greater than 14 percent. The sampler is made as in Figure 6a) of GB 16410-2020 from stainless steel, the sampling tube being of polytetrafluoroethylene or another material that does not adsorb nitrogen oxides, and it is placed as in Figure 6b). The nitrogen oxide content is calculated by formula (A.1), which corrects the measured content of the sample for the nitrogen oxide content of the room air, measured at the same time, and for the oxygen content of the sample, referred to an excess air factor of one.

B Annex B (informative) Cut-out dimensions for building in a built-in stove

Table B.1 gives the cut-out width, depth and corner radius in millimetres against a code: K1, 270 by 390; K2, 300 by 400; K3, 630 by 330; K4, 650 by 350; K5, 680 by 350; K6, 680 by 380; K7, 700 by 400; and K8, 760 by 400. The corner radius for every code is 20 or 10.