www bzfxw com BRITISH STANDARD BS EN 625 1996 Gas fired central heating boilers — Specific requirements for the domestic hot water operation of combination boilers of nominal heat input not exceeding[.]
BRITISH STANDARD Gas-fired central heating boilers — Specific requirements for the domestic hot water operation of combination boilers of nominal heat input not exceeding 70 kw The European Standard EN 625:1995 has the status of a British Standard BS EN 625:1996 BS EN 625:1996 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee GSE/29, Domestic gas-fired central heating boilers, upon which the following bodies were represented: Association of Manufacturers of Domestic Unvented Supply Systems Equipment (MODUSSE) Boilers and Radiator Manufacturers’ Association Limited British Gas plc Department of the Environment (Building Research Establishment) Department of the Environment (Property and Buildings Directorate) Department of Trade and Industry (Consumer Safety Unit, CA Division) Electricity Association Society of British Gas Industries Co-opted members This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 April 1996 © BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference GSE/29 Draft for comment 92/71976 DC ISBN 580 25367 Amendments issued since publication Amd No Date Comments BS EN 625:1996 Contents Committees responsible National foreword Foreword Text of EN 625 List of references © BSI 08-1999 Page Inside front cover ii Inside back cover i BS EN 625:1996 National foreword This British Standard has been prepared under the direction of the Engineering Sector Board and is the English language version of EN 625:1995 Gas-fired central heating boilers — Specific requirements for the domestic hot water operation of combination boilers of nominal heat input not exceeding 70 kW, published by the European Committee for Standardization (CEN) EN 625 was produced as the result of international discussion in which the UK took an active part There has previously been no direct British Standard equivalent to this standard It is assumed that the execution of the provisions of this document is entrusted to suitably qualified and experienced persons Cross-references Publication referred to Corresponding British Standard EN 297:1994 BS EN 297:1994 Gas-fired central heating boilers — Type B11 and B11BS boilers fitted with atmospheric burners of nominal heat input not exceeding 70 kW EN 437:1994 BS EN 437:1994 Specification for test gases, test pressures and categories of appliance, for gas appliances A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application Compliance with a British Standard does not of itself confer immunity from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages to 16, an inside back cover and a back cover This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover ii © BSI 08-1999 EUROPEAN STANDARD EN 625 NORME EUROPÉENNE September 1995 EUROPÄISCHE NORM ICS 27.060.30; 91.140.10; 91.140.60 Descriptors: Heaters, gas appliances, central heating, water production, boilers, burners, definitions, equipment specifications, performance evaluation, tests, safety, energy, consumption, operating requirements, marking, name plates, classifications English version Gas-fired central heating boilers — Specific requirements for the domestic hot water operation of combination boilers of nominal heat input not exceeding 70 kW Chaudières de chauffage central utilisant les combustible gazeux — Exigences spécifiques la fonction eau chaude sanitaire des chaudières deux services dont le débit calorifique nominal est inférieur ou égal 70 kW Heizkessel für gasförmige Brennstoffe — Spezielle Anforderungen an die Trinkwasserseitige Funktion von Kombi-Kesseln mit einer Nennwärmebelastung kleiner als oder gleich 70 kW ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ This European Standard was approved by CEN on 1995-03-06 CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1995 All rights of reproduction and communication in any form and by any means reserved in all countries to CEN and its members Ref No EN 625:1995 E EN 625:1995 Foreword This European Standard was prepared by Technical Committee CEN/TC 109, Central heating boilers using gaseous fuels, of which the secretariat is held by NNI Other types of boiler including boilers of higher nominal heat input which are excluded from this European Standard are dealt with in separate standards This European Standard has been prepared under a mandate granted to CEN by the European Commission and the European Free Trade Association, and supports the essential requirements of the EU Directive In particular, matters which relate to quality assurance systems, production tests and the certification of auxiliary controls are not dealt with in this standard In respect of potential adverse effects on the quality of water intended for human consumption, caused by the product covered by this standard: 1) This standard provides no information as to whether the product may be used without restriction in any of the member states of the EU or EFTA 2) It should be noted that, while awaiting the adoption of verifiable European criteria, existing national regulations concerning the use and/or the characteristics of this product remain in force In compliance with the common rules of CEN/CENELEC, the following countries are bound to apply this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom For relationship with EU Directives, see informative Annex ZA, which is an integral part of this standard This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 1996, and conflicting national standards shall be withdrawn at the latest by March 1996 ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ © BSI 08-1999 EN 625:1995 Contents Foreword Scope Normative references Definitions 3.1 Combination boiler 3.2 “Summer” operating mode 3.3 Specific rate 3.4 Nominal domestic hot water heat input 3.5 Maximum water service pressure 3.6 Tank 3.7 Thermal store 3.8 Temperature relief valve 3.9 Proportional control of the domestic hot water operation 3.10 Thermostatic control of the domestic hot water operation 3.11 Temperature holding thermostat Constructional requirements 4.1 Materials and method of construction of components of the domestic water circuit 4.2 Domestic water connections 4.3 Soundness of the domestic water circuit 4.4 Adjusting, control and safety devices for the domestic hot water circuit Operational requirements 5.1 General 5.2 Safety of the domestic hot water circuit 5.2.1 Instantaneous and storage types 5.2.2 Instantaneous type 5.2.3 Storage type 5.3 Rational use of energy 5.3.1 Useful efficiency 5.3.2 Losses 5.4 Fitness for purpose 5.4.1 Instantaneous and storage types — Specific rate 5.4.2 Instantaneous type Test methods 6.1 General 6.1.1 Adjustment of the domestic water pressure Page 5 5 5 5 5 6 6 6.1.2 6.2 Operation of the boiler Safety of the domestic hot water circuit 6.2.1 Instantaneous and storage types 6.2.2 Instantaneous type 6.2.3 Storage type 6.3 Rational use of energy 6.3.1 Useful efficiency 6.3.2 Losses 6.4 Fitness for purpose 6.4.1 Instantaneous and storage types — Specific water rate 6.4.2 Instantaneous type Marking and instructions 7.1 Data plate of the boiler and/or the tank 7.2 Instructions 7.2.1 Technical instructions for the installer 7.2.2 Operating instructions for the user Annex ZA (informative) Clauses of this European Standard addressing essential requirements or other provisions of EU Directives Figure — Illustration of the test tank rig [see 6.3.2.1.3 a)] Table ZA.1 Table ZA.2 Table ZA.3 Page 8 8 9 9 11 11 11 12 12 12 12 12 ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ © BSI 08-1999 6 6 6 14 13 15 16 16 7 7 7 7 7 8 ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ blank EN 625:1995 Scope Definitions This standard supplements standards EN 297, prEN 483 and prEN 677, hereafter called “boiler standards” It specifies the supplementary requirements and tests for the construction, safety, rational use of energy, fitness for purpose, classification and marking related to the domestic hot water operation of combination boilers The domestic hot water is produced by either the instantaneous or storage principle The domestic hot water production is integrated or coupled, and the whole being marketed as a single unit This standard does not apply to two appliances included in the same case which operate independently of each other, a boiler and a water heater, even if they have a common flue This standard only covers type testing For the purposes of this standard the following definitions apply Normative references This European Standard incorporates by dated or undated reference, provisions from other publications These normative references are cited at the appropriate places in the text and the publications are listed hereafter For the dated references, subsequent amendments to or revisions of any of these publications apply to this standard only when incorporated in it by amendment or revision For undated references, the latest edition of the publication referred to applies EN 297:1994, Gas-fired central heating boilers — Type B11 and B11BS boilers fitted with atmospheric burners of nominal heat input not exceeding 70 kW EN 297/prA2, Gas-fired central heating boilers — Type B11 and B11BS boilers fitted with atmospheric burners of nominal heat input not exceeding 70 kW (determination of efficiency) EN 437, Test gases — Test pressures — Appliance categories prEN 483, Gas-fired central heating boilers with atmospheric burners — Type C boilers of nominal heat input not exceeding 70 kW prEN 677, Gas-fired central heating boilers — Specific requirements for condensing boilers with nominal heat input not exceeding 70 kW ISO 7-1, Pipe threads where pressure-tight joints are made on the threads — Part 1: Designation, dimensions and tolerances ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Designation, dimensions and tolerances ISO 274, Copper tubes of circular section — Dimensions 3.1 combination boiler boiler designed both for central heating and for the production of domestic hot water Depending on its type of domestic hot water production, the combination boiler is classed as follows, in accordance with the manufacturer’s declaration — instantaneous type Combination boilers which can continuously supply the specific domestic hot water rate D stated by the manufacturer — storage type Combination boilers which can intermittently supply the specific domestic hot water rate D stated by the manufacturer 3.2 “summer” operating mode operating mode in which the boiler only provides heating of the domestic water ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ © BSI 08-1999 3.3 specific rate the domestic hot water rate declared by the manufacturer, corresponding to a mean temperature rise of 30 K, that the boiler can supply in two successive delivery periods Symbol: D; Unit: litres per minute (l/min) 3.4 nominal domestic hot water heat input the value of the heat input in the domestic hot water mode indicated by the manufacturer Symbol: Qnw; Unit: kilowatt (kW) 3.5 maximum water service pressure the maximum pressure permitted in the domestic water circuit, as declared by the manufacturer Symbol: PMW; Unit: bar 3.6 tank reservoir of domestic water 3.7 thermal store heat reservoir sited mainly in heating water, as opposed to the domestic hot water storage in the tank EN 625:1995 3.8 temperature relief valve a valve that opens automatically at a given temperature of maximum 100 °C to discharge the domestic hot water 3.9 proportional control of the domestic hot water operation means of control in which the gas rate is subordinated proportionally to the domestic hot water rate; the proportioning factor may be adjustable 3.10 thermostatic control of the domestic hot water operation means of control in which the gas rate is subordinated to a thermostatic device controlling the domestic hot water temperature, the set point of the device may be adjustable 3.11 temperature holding thermostat a device which maintains the water in the tank or the thermal store at a given temperature Constructional requirements It is checked that the assembly meets constructional requirements by visual examination of the boiler and possibly the tank, and also by inspection of the technical file 4.1 Materials and method of construction of components of the domestic water circuit Materials shall be appropriate for their use, under intended application and at the maximum water pressure stated by the manufacturer The requirements relating to thermal insulation and its use specified in the “boiler standards” only apply to parts of the domestic water circuit likely to come into contact with flames or sited close to the combustion products outlet The materials of the parts containing domestic water shall not affect the quality of the domestic water in respect of either health or taste The whole of the domestic hot water circuit shall be made up of corrosion resistant materials or shall be protected against corrosion 4.2 Domestic water connections Threaded connections shall comply with ISO 228-1 or ISO 7-1 If copper tubes are used for the connection, the end of the tube shall comply with ISO 274 In accordance with the manufacturer’s instructions, the domestic water circuit shall be able to be drained, without the discharge of water compromising electrical safety 4.3 Soundness of the domestic water circuit The domestic hot water circuit and the heating circuit shall be separate If an actuator or a control has a sliding shaft or a link with the diaphragm separating: — the gas circuit and the heating water circuit; — the heating water circuit and the domestic water circuit; — the gas circuit and the domestic water circuit; there shall be an air vent between these circuits The area of this aperture shall be at least 19 mm2 and it shall be possible to introduce a 3,5 mm pin gauge into it 4.4 Adjusting, control and safety devices for the domestic hot water circuit If necessary, the domestic hot water circuit shall be protected with control and safety devices to comply with the requirements, “Thermostats and water temperature limiting devices — General” of clause of EN 297 and clause of prEN 483 The tank shall be fitted with a device for controlling the water temperature This device shall allow a temperature to be attained which is sufficient to prevent the build up of bacteria (see 5.2.3.3) Where circumstances require, and the appliance is equipped with a temperature relief valve, any device controlling the temperature of the domestic hot water shall act before this valve ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ Operational requirements 5.1 General If the nominal heat input in domestic hot water mode exceeds the nominal heat input in the central heating mode, the safety requirements of the “boiler standards” given below are checked at the nominal heat input in the domestic hot water mode and at the maximum water temperature: — soundness of the combustion circuit; — limiting temperatures; — ignition, cross lighting and flame stability; — flame supervision device; — combustion products discharge safety device (for type B11BS boilers); — carbon monoxide © BSI 08-1999 EN 625:1995 5.2 Safety of the domestic hot water circuit 5.2.3.3 Temperature of the domestic hot water 5.2.1 Instantaneous and storage types Under the test conditions of 6.2.3.3, it shall be possible to adjust to or obtain a domestic hot water temperature of at least 60 °C in the tank 5.2.1.1 Soundness of parts containing domestic water Under the test conditions of 6.2.1.1, the parts containing domestic water shall withstand the test pressure without permanent distortion or soundness defects, with respect to the outside or the heating circuit 5.2.1.2 Overheating of the domestic hot water by the heating circuit Under the test conditions of 6.2.1.2, the domestic hot water temperature shall not exceed 95 °C 5.2.1.3 Failure of the domestic hot water temperature control device Under the test conditions of 6.2.1.3: — for boilers in which the domestic water circuit is not in direct contact with the combustion products, with normal control out of operation and according to the option chosen, at least the requirement relating to the limit thermostat (3.5.7.3.2.1 test no of EN 297 or 6.5.7.3.2.1 test no of prEN 483) or the safety temperature limiter (3.5.7.3.2.2 of EN 297 or 6.5.7.3.2.2 of prEN 483) shall be met — for boilers in which the domestic water circuit comes into total or partial contact with the combustion products, the domestic water temperature limiting device shall at least cause safety shutdown before the tap water reaches a temperature of 100 °C 5.2.2 Instantaneous type 5.2.2.1 Maximum domestic hot water temperature Under the test conditions of 6.2.2.1, the domestic hot water temperature shall not exceed 95 °C 5.2.2.2 Overheating of the domestic hot water Under the test conditions of 6.2.2.2, the domestic hot water temperature shall not exceed 95 °C 5.2.3 Storage type 5.2.3.1 Maximum temperature of the domestic hot water Under the test conditions of 6.2.3.1, the domestic hot water temperature shall not exceed 95 °C 5.2.3.2 Overheating of the domestic hot water Under the test conditions of 6.2.3.2, for boilers in which part of the tank is in contact with products of combustion, the domestic hot water temperature shall not exceed 95 °C © BSI 08-1999 5.3 Rational use of energy 5.3.1 Useful efficiency The considered useful efficiency is that measured in the central heating mode 5.3.2 Losses The losses of the boiler and the tank (where applicable) measured under the test conditions of 6.3.2, shall be less than the value given by the following formula: qs = 0,014 V2/3 + 0,02Qnw where: qs are the losses of the boiler and the tank in kilowatts (kW); V is the water capacity of the tank (including the water in any integral heat exchanger) and/or the thermal store (if applicable) in litres (l); Qnw is the nominal domestic hot water heat input of the boiler, in kilowatts (kW) 5.4 Fitness for purpose 5.4.1 Instantaneous and storage types — Specific rate Under the test conditions of 6.4.1, the measured value of the specific rate shall not be more than % below the value D stated by the manufacturer on the data plate 5.4.2 Instantaneous type 5.4.2.1 Nominal domestic hot water heat input Under the test conditions of 6.4.2.1, the nominal domestic hot water heat input shall be obtained or may be adjusted to within ± % 5.4.2.2 Water pressure to obtain the nominal heat input Under the test conditions of 6.4.2.2, the heat input obtained shall be at least 95 % of the heat input obtained in 6.4.2.1 5.4.2.3 Obtaining the domestic hot water temperature Under the conditions of 6.4.2.3, it shall be possible to achieve or adjust to, a water rate that corresponds to a temperature of between 50 °C and 80 °C for boilers with a thermostatic control or a temperature rise at the boiler outlet of between 45 K and 65 K for boilers with proportioning control EN 625:1995 5.4.2.4 Heating-up time of the domestic hot water Under the test conditions of 6.4.2.4, the heating-up time shall not exceed Test methods 6.1 General Unless otherwise specified, the general test conditions of the “boiler standards” are supplemented as stated below: — cold water: (10 ± 2) °C; — hot water: 50 °C or as near as possible; — central heating water (if necessary): see “boiler standards” (flow 80 °C, return 60 °C) For the tests: — the domestic water pressure is the difference between the static inlet and outlet pressures of the boiler measured as close as possible to the boiler; — the inlet and outlet temperatures of the domestic water are measured in the centre of the flow and as close as possible to the boiler In certain tests, a low inertia thermometer is used “Low inertia thermometer” means a measuring instrument with a response time such that 90 % of the final temperature rise, in the range 15 °C to 100 °C, is obtained within s when the sensor is plunged into still water 6.1.1 Adjustment of the domestic water pressure The domestic water pressure shall be adjusted to ± % of the required value 6.1.2 Operation of the boiler Except where otherwise specified, the tests are carried out with the boiler operating in the domestic water mode and the “summer” operating mode 6.2 Safety of the domestic hot water circuit 6.2.1 Instantaneous and storage types 6.2.1.1 Soundness of the parts containing domestic water The domestic water circuit is subjected to a pressure of 1,5 times the maximum pressure given on the data plate for 10 It is checked that the requirements of 5.2.1.1 are met 6.2.1.2 Overheating of the domestic hot water by the central heating circuit The appliance operates continuously for h at the nominal heat input in the central heating mode, without drawing domestic hot water A draw off at the specific rate D is then carried out and the requirement of 5.2.1.2 is checked 6.2.1.3 Failure of the domestic hot water temperature control device The requirement of 5.2.1.3 is checked after the control device of the domestic hot water circuit has been put out of operation: — for boilers in which the domestic hot water circuit does not come into direct contact with the combustion products, testing is carried out according to the test methods relating to the limit thermostat (4.5.7.3.2.1 test no of EN 297 or 7.5.7.3.2.1 test no of prEN 483) or the safety temperature limiter (4.5.7.3.2.2 of EN 297 or 7.5.7.3.2.2 of prEN 483); — for boilers in which the domestic water circuit comes into total or partial contact with the combustion products, the boiler’s hot water tapping rate is progressively decreased until the point is reached where the burner is shut off Where the boiler is fitted with a range rating device, the test is carried out at the maximum adjusted heat input in the central heating mode 6.2.2 Instantaneous type 6.2.2.1 Maximum temperature of the domestic hot water The boiler is supplied with an appropriate reference gas (EN 437) and is operated at the nominal domestic hot water heat input with a domestic water supply pressure of bar Starting with this bar supply pressure, the pressure is progressively reduced until the burners are extinguished The water outlet temperature is measured continuously with a low inertia thermometer The maximum temperature is measured and shall satisfy the requirements of 5.2.2.1 6.2.2.2 Overheating of the domestic hot water The boiler is supplied with an appropriate reference gas (EN 437) and is operated at the nominal domestic hot water heat input The water rate and, where appropriate, any water temperature control are adjusted to obtain the maximum water temperature at the nominal domestic hot water heat input The boiler is supplied with an appropriate reference gas (EN 437) The central heating circuit thermostat is set at its maximum position © BSI 08-1999 EN 625:1995 After the boiler has operated for 10 min, the hot water delivery tap is turned off quickly After 10 s the tap is turned on quickly and the highest temperature at the centre of the flow, as close as possible to the boiler outlet, is measured by means of a low inertia thermometer The boiler remains in operation until it has again reached its steady state condition The same measurements are made during similar operating cycles, but with the time that the draw off is stopped increased each time by 10 s, until the maximum temperature is obtained It is checked that the requirement of 5.2.2.2 is met 6.3 Rational use of energy 6.2.3 Storage type The losses from the boiler/tank assembly are determined by adding up the losses from the boiler and the tank The manufacturer states how the tank has to be separated from the boiler, and which pipework has to be taken into account in the boiler losses and which will be counted with the tank 6.2.3.1 Maximum temperature of the domestic hot water The boiler is supplied with an appropriate reference gas (EN 437) and is operated at the nominal domestic hot water heat input with the domestic water thermostat at its maximum position A draw off is carried out after a shut down of the burner The maximum temperature measured shall meet the requirement of 5.2.3.1 6.2.3.2 Overheating of the domestic hot water The test commences after the tank or the thermal store has reached temperature and after the burner has been shut down a second time by the controls Water is drawn off several times at a rate corresponding to % of the water capacity of the tank, in litres per minute On each occasion, water is drawn until the burner ignites and at least 95 % of the nominal domestic hot water heat input is obtained The next draw off then takes place immediately after the burner shuts down, and so on until the maximum temperature is obtained For modulating burners or burners with several rates, the next drawing takes place when the gas rate has decreased at least to 50 % of the maximum domestic hot water heat input reached As each draw off commences, the temperature of the delivered water is measured and it is checked that the requirement of 5.2.3.2 is met 6.3.1 Useful efficiency The test is carried out in the central heating mode in the “boiler standards” 6.3.2 Losses Depending on the way in which hot water is produced, the requirement of 5.3.2 is checked under the test conditions defined below 6.3.2.1 Tank which can be disconnected from the boiler 6.3.2.1.1 General 6.3.2.1.2 Boiler For the boiler, the losses (standby losses) are measured as in amendment EN 297/pr A2 The exchanger for the tank is disconnected from the boiler Also, where the boiler and the tank are coupled within the same case, the losses from the boiler alone are measured with the tank empty 6.3.2.1.3 Tank For the tank, the following mode of operation is used: If the tank and the boiler are coupled within the same case, the losses from the tank alone are determined with the boiler empty a) Preliminary conditions The test is carried out with a rig equivalent to that described in Figure 1, in a room where the ambient temperature is between 15 °C and 25 °C, with a permitted temperature variation of ± °C during the test The installation includes an electrical resistance and a circulating pump (long circuit of Figure 1) 6.2.3.3 Temperature of the domestic hot water Where applicable, the adjuster is placed in the position stated by the manufacturer After a controlled shutdown of the boiler, a draw off is carried out for 10 at a rate equivalent to % of the water capacity of the tank per minute or at the minimum rate stated by the manufacturer which allows burner ignition if this is greater than % of the capacity of the tank per minute After min, it is checked that the requirements of 5.2.3.3 are met © BSI 08-1999 EN 625:1995 Before the test is carried out, the tank is placed in the position recommended by the manufacturer For a tank with two positions, vertical or horizontal, the test is done in the vertical position It is filled with water heated to a temperature of (65 ± 2) °C by circulation in a closed circuit, in which the tank and its exchanger are arranged in series The tank domestic water temperatures are deemed to have reached uniformity at the time t1 that circulation stops, if the following conditions are met: — the difference between the domestic water outlet temperature (Ts) and the domestic water inlet temperature (Te) remains less than K continuously for 15 before time t1; — the inlet temperature (Te) has not changed by more than K during this period It is assumed that the mean water temperature (To) of the tank at moment t1 is equal to the arithmetic mean of the inlet and outlet temperatures at that moment: Te + T T o = s2 The preliminary conditions are met if this temperature To is equal to (65 ± 2) °C b) Cooling of the tank and determination of the corrected final mean temperature (Tfc) At t1, valves and shown in Figure are shut off, and all the water connections are disconnected and sealed at valves and The parts of the pipework external to the tank shall be carefully insulated so that the heat losses attributable to them are negligible compared to the losses from the tank The tank is left to cool for a measured time of 24 h ± 20 (t2) The ambient temperature is measured at least every hour and the arithmetic mean (Tamb) calculated The final mean water temperature (Tf) of the tank at time t2 is determined by the following method; — the connections of the short circuit of Figure are remade and the circulating pump is put into operation; — the mean water temperature of the tank at time t2 is that obtained after stabilization when the temperature difference between the inlet and outlet is less than K The re-circulation time is taken into account in the cooling time; 10 — the corrected final mean water temperature (Tfc) of the tank is calculated by taking account of the water mass and water temperature of the test rig short circuit This connecting circuit will be designed such that the correction to the final temperature is less than 0,5 K for a tank of capacity exceeding 50 l and K for a tank of capacity not exceeding 50 l The corrected final mean water temperature (Tfc) of the tank is calculated as follows: (V × Tfc) + (Vb × Ta) = (V + Vb) × Tf whence: where: Tfc is the corrected final mean water temperature in degrees Celsius (°C); Tf is the mean water temperature of the tank measured at time t2 in degrees Celsius (°C); Ta is the ambient temperature at time t2 in degrees Celsius (°C) (assuming that at the end of 24 h the short circuit is at ambient temperature); V is the water capacity of the tank (including the water in any integral heat exchanger), in litres (l) This value is declared by the manufacturer and checked from the drawings; Vb is the volume of water in the connecting short circuit of the test rig, in litres (l) c) Calculation of the losses of the tank The value of the losses of the tank is given by the following relationship: or © BSI 08-1999 EN 625:1995 where qa45 are the losses of the tank for a temperature rise of 45 K, in kilowatts (kW); After a waiting time of 20 after the end of the first drawing, a new water drawing is carried out for 10 and the temperature and water rate are recorded For each drawing the following is calculated: t2 – t1 is the period of cooling, in hours (h); To is the mean water temperature of the tank at time t1, in degrees Celsius (°C); Tfc is the corrected mean water temperature of the tank at time t2, in degrees Celsius (°C); Tamb is the mean ambient temperature during cooling, in degrees Celsius (°C); V is the water capacity of the tank (including the water in any integral heat exchanger), in litres (l) This value is declared by the manufacturer and checked from the drawings 6.3.2.2 Tank or thermal store which is integral with and cannot be separated from the boiler The losses for the boiler tank or the boiler thermal store assembly are determined as stated for the boiler alone in amendment EN 297/pr A2, or for a difference between the temperature declared by the manufacturer in 6.4.1 and the ambient temperature if this difference is greater than 45 K For this test, the tank and its exchanger (if appropriate) are connected in series with the boiler 6.4 Fitness for purpose 6.4.1 Instantaneous and storage types — Specific rate The boiler is supplied with an appropriate reference gas (EN 437) at the nominal domestic hot water heat input with an inlet water pressure of bar The domestic hot water temperature is adjusted, where possible, to obtain an average temperature rise as close as possible to 30 K which permits the nominal domestic hot water heat input to be obtained Before the test, the boiler is in the “summer” operating mode, at thermal equilibrium, without any draw off For storage type boilers, the setting of the domestic hot water thermostat is adjusted to 65 °C or the value stated by the manufacturer for boilers with integral, non-removable tanks If by design, the 65 °C temperature cannot be achieved, the test is carried out at the closest possible temperature to 65 °C The first drawing is carried out no earlier than the second controlled shut down of the burner and lasts 10 The temperature and the water rate are recorded © BSI 08-1999 where Di is the specific rate D1 and D2, determined respectively during the first and second draw offs, in litres per minute (l/min); mi(10) is the quantity of water collected during the first or second draw off, in litres (l); %t is the mean effective temperature rise of the collected water, in kelvin (K) If the difference between D1 and D2 does not exceed 10 % of their average value, the requirement applies to: D + D2 If the difference between D1 and D2 exceeds 10 % of their average value, the requirement applies to the lowest value of the two It is checked that the requirements of 5.4.1 are met 6.4.2 Instantaneous type 6.4.2.1 Nominal domestic hot water heat input The test is carried out with each appropriate reference gas (EN 437) at a water pressure of bar The gas rate may be adjusted in accordance with the manufacturer’s instructions A water draw off is carried out to check that the requirement of 5.4.2.1 is satisfied 6.4.2.2 Water pressure to obtain the nominal domestic hot water heat input The test is carried out by lowering the water pressure to the minimum value stated by the manufacturer and it is checked that the requirement of 5.4.2.2 is satisfied 6.4.2.3 Obtaining the domestic hot water temperature The boiler is adjusted as stated in 6.1 and 6.4.2.1 with an appropriate reference gas (EN 437) Then draw offs are carried out at water pressures of 2, 3, and bar or at the water pressures declared by the manufacturer if they are less than these values The domestic hot water rate is adjusted in accordance with the technical instructions (7.2.1) and the information on the data plate (7.1.1) 11 EN 625:1995 In the steady state, it is checked that the requirement of 5.4.2.3 is met for the maximum and minimum positions of the central heating thermostat if it is adjustable 6.4.2.4 Heating-up time of the domestic hot water The boiler is adjusted in accordance with 6.1 and 6.4.2.1 with an appropriate reference gas (EN 437) The central heating thermostat and/or the temperature holding thermostat for the domestic hot water, if it exists, is set to the minimum temperature position The water rate and the means of temperature adjustment (if it is adjustable) are adjusted to obtain the following water temperature conditions at the nominal domestic hot water heat input and in the steady state: — boilers with fixed output or proportioning control: a temperature rise of 45 K; — boilers with thermostatic control: an outlet temperature of 50 °C Then the boiler is put into thermal equilibrium without any drawing off When thermal equilibrium is achieved, or at the end of a control cycle, if it exists, the drawing tap is opened The flow time is measured from the opening of the tap until 90 % of the temperature rise or the water outlet temperature stated above is attained These temperatures are measured with a low inertia thermometer It is checked that the requirement of 5.4.2.4 is met Marking and instructions 7.1 Data plate of the boiler and/or the tank 7.2 Instructions 7.2.1 Technical instructions for the installer The technical instructions for the installer specified in the “boiler standards” shall be supplemented as follows: — for all types of boilers: — the information given on the data plate as specified in 7.1; — the mass rate, in grams per second (g/s), and the average temperature of the combustion products in the domestic water mode, in degrees Celsius (°C), (measured under the conditions of 6.4.1); — for storage type combination boilers: — where necessary, describe how the boiler and the tank are connected; — indicate that it will be necessary to fit safety devices specified in local installation regulations, if they have not been fitted on the boiler by the manufacturer; — for instantaneous type combination boilers; — the minimum pressure at the inlet to the domestic water circuit 7.2.2 Operating instructions for the user Operation instructions for the user specified in the “boiler standards” shall be supplemented by information necessary for normal domestic hot water operation In particular, they shall state: — the temperature in the tank or the thermal store necessary to obtain the claimed specific water rate; — the precautions to be taken in case of freezing The data from the “boiler standards” on the data plate shall be supplemented by the following information for combination boilers: — nominal heat input in the domestic hot water mode (Qnw), in kilowatts (kW), if there are different nominal heat inputs for the central heating and domestic water modes; — maximum water service pressure for the domestic water circuit (P.MW), in bars; — value of the specific water rate, D, (either on the boiler or on the tank), to the first decimal place, in litres per minute (l/min) 12 © BSI 08-1999 EN 625:1995 Figure — Illustration of the test tank rig [see 6.3.2.1.3 a)] © BSI 08-1999 13 EN 625:1995 Annex ZA (informative) Clauses of this European Standard addressing essential requirements or other provisions of EU Directives This European Standard has been prepared under a mandate given to CEN, by the European Commission and the European Free Trade Asociation and supports essential requirements of EU Directive WARNING: other requirements and other EU Directives may be applicable to the products falling within the scope of this standard The following clauses of this standard are likely to support requirements of Directive 90/396/EEC “Gas appliances” Compliance with these clauses of this standard provides one means of conforming with the specific essential requirements of the Directive concerned and associated EFTA regulations 14 © BSI 08-1999 EN 625:1995 Table ZA.1 Essential requirements Object Clauses and/or paragraphs in the standard which comply wholly or in part with the essential requirement Annex I of the Directive — general conditions 1.1 Safety of operation 4.4 to 5.1 and 5.2.3.3 1.2 Marking and instructions Installation instructions Operating instructions for the user Warnings on the appliance and on the packaging Official languages 7.2 7.2.1 7.2.2 EN* EN* 1.2.1 Information in the installation instructions Gas type Supply pressure Combustion air rate Discharge of combustion products EN* EN* EN* EN* 1.2.2 Contents of the operating instructions for the user EN* and 7.2.2 1.2.3 Warning on the appliance and packaging EN* 1.3 Equipment EN* Materials 2.1 Characteristics EN* and 4.1 2.2 Guarantee EN* Design and construction 3.1 3.1.1 General Resistance to contraints EN* and 4.1 3.1.2 Condensation EN* 3.1.3 Risk of explosion EN* 3.1.4 Water penetration 4.3 3.1.5 Normal fluctuation of auxiliary energy EN* and 5.2 3.1.6 Abnormal fluctuation of auxiliary energy EN* and 5.2 3.1.7 Hazards of electrical origin EN* 3.1.8 Pressurised parts EN* and 5.2.1.1 3.1.9 Failure of safety devices: — flame supervision device; — combustion products discharge safety device (type B11BS); — automatic burner control systems; — overheat protection; — gas circuit EN* EN* EN*, 4.4 and 5.2.1.3 EN*, 4.4, 5.2.1.2 and 5.2.1.3 EN* 3.1.10 Safety/adjustment EN* 3.1.11 Protection of parts set by the manufacturer EN* 3.1.12 Marking of taps, adjusting or control devices EN* 3.2 3.2.1 Unburnt gas release Risk of gas leakage EN* 3.2.2 Risk of gas accumulation in the appliance EN* 3.2.3 Risk of gas accumulation in the rooms EN* © BSI 08-1999 15 EN 625:1995 Table ZA.1 Essential requirements Object Clauses and/or paragraphs in the standard which comply wholly or in part with the essential requirement 3.3 Ignition: — ignition and re-ignition; — cross-lighting 3.4 3.4.1 Combustion Flame stability Concentration of substances harmful to health in the combustion products EN* EN* 3.4.2 Release of combustion products EN* 3.4.3 Release of combustion products into the room for appliances connected to a flue EN* (type B11BS) under abnormal draught conditions 3.4.4 CO limit in the room (independent flueless heating appliances and flueless intantaneous water heaters) Not applicable 3.5 Rational use of energy EN* and 5.3 3.6 3.6.1 Temperatures Floor and adjacent walls EN* 3.6.2 Knobs EN* 3.6.3 Temperature of external surfaces EN* 3.7 Foodstuffs and water used for sanitary purposes Foreword and 4.1 NOTE EN* EN* EN* not specific to the domestic hot water operation and already covered in the “boiler standards” Table ZA.2 Certification of conformity Object Annex II of the Directive NOTE Clauses and/or paragraphs in the standard which comply wholly or in part with the requirement EN* not specific to the domestic hot water operation and already covered in the “boiler standards” Table ZA.3 EC mark and inscriptions Object Clauses and/or paragraphs in the standard which comply wholly or in part with the requirement Annex III of the Directive CE mark EN* Appliance or its data plate: — CE mark; — manufacturer’s name or identification symbol; — trade name; — electrical supply; — appliance category; — installation information EN* EN* EN* EN* EN* 7.1 NOTE 16 EN* not specific to the domestic hot water operation and already covered in the “boiler standards” © BSI 08-1999