BS EN 778-2009 pdf download.Domestic gas-fired forced convection air heaters for space heating not exceeding a net heat input of 70 kW, without a fan to assist transportation of combustion air and/or combustion products.
The quality and thickness of materials used in the construction of the appliance and the method of assembling the various parts, shall be such that the constructional and performance characteristics do not alter significantly during a reasonable life under normal conditions of installation and use.
When the appliance is installed in accordance with the manufacturer’s instructions, all components, including its POCED in the case of Type B4, C1, C2, C3 and C4 appliances, shall withstand the mechanical, chemical and thermal conditions to which they may be subjected in the course of normal use.
In addition, the appliance shall be designed in such a way that there is no condensation at the operating temperature provided by the controls.
If condensation occurs at start-up, this shall not affect the operational safety. With the exception of the outlet of the flue system. any condensate formed shall not drop outside the appliance.
Copper shall not be used for gas carrying parts where its temperature is likely to exceed 100 °C. Asbestos or materials containing asbestos shall not be used
Hard solder containing cadmium in its formulation shall not be used. Solder that has a melting point below 450 °C after application shall not be used for gas carrying parts.
Materials downstream of the heat exchanger shall be corrosion-resistant or be effectively protected against corrosion. Zinc-coated steel materials are not allowed if they come into contact with combustion products during normal operation.
Where appropriate, materials used on the appliance shall be non-combustible in accordance with the requirements of ISO 1182:2002.
5.1.3 Accessibility for maintenance and use
Parts that are intended to be removable for maintenance or cleaning shall be readily accessible, shall be readily capable of correct assembly and difficult to assemble incorrectly. Such parts shall be impossible to assemble incorrectly where incorrect assembly would create a hazardous condition or result in damage to the appliance and its controls.
It shall be possible to clean the combustion chamber and the parts in contact with combustion products in accordance with the manufacturer’s instructions without using special tools unless these are supplied as necessary accessories with the appliance.
Access shall be possible to all handles, buttons etc. required during normal use of the appliance, without having to remove any part of the case. For this purpose, the opening of a door or access panel is permitted.
Constructional parts accessible during use and maintenance shall be free from sharp edges and corners that might cause damage or personal injury during use or maintenance.
5.1.4 Thermal Insulation
Any thermal insulation shall retain its insulating properties under the influence of heat and ageing. The thermal insulation shall withstand the thermal and mechanical stresses normally expected during boiler operation. The insulation shall be non-combustible, securely located and shall be protected against mechanical damage and condensate.
5.1.5 Gas connection
The gas connection to the appliance shall be accessible.
The clearance around the gas connection, after removing the appliance case If necessary, shall be adequate to allow the use of tools required to make the connection. It shall be possible to make all the connections without the use of special tools.
It shall be possible to connect the appliance by rigid metallic means to the gas supply.
If the appliance has a threaded connection, this thread shall comply with EN ISO 228-1:2003, EN 10226-1:2004 or EN 10226-2:2005. In the first case (EN ISO 228-1:2003). the end of the appliance inlet connection shall be sufficiently flat to allow the use of a sealing washer.
If flanges are used, they shall comply with ISO 7005-1:1992, ISO 7005-2:1988 or ISO 7005-3:1988, as appropriate, and the manufacturer shall provide the counterfianges and sealing gaskets.
The conditions of connections prevailing in the various countries are given in A,6.
5.1.6 Soundness
5.1.6.1 Soundness of the gas circuit
Holes (e.g. for screws and studs) intended for the assembly of parts shall not open into gasways. The wall thickness between dnllings and gasways shall be at least 1 mm. This does not apply to orifices for measurement purposes.
The soundness of parts and assemblies making up the gas circuit and likely to be dismantled for routine maintenance in situ shall be achieved by means of mechanical joints (e.g. metal-to-metal joints, gasket, or 0- ring joints) without the use of sealing materials (e.g. tape, paste or liquid). However, the sealing materials (e.g. tape, paste or liquid) may be used for permanent assemblies. Sealing materials shall remain effective under normal conditions of appliance use.
5.1.6.2 Soundness of the combustion circuit
Any means used to achieve soundness of the combustion circuit shall be such that it does not deteriorate under normal conditions of use and maintenance.BS EN 778-2009 pdf download.