This British Standard specifies requirements for the selection, installation, inspection, commissioning, servicing and maintenance of gas-fired boilers for central heating and other purposes, which have a total rated heat input not exceeding 70kW based on net calorific value. This includes cookers with integral boilers used to provide central heating. It applies to boilers utilizing 1st, 2nd or 3rd family gases designed to operate in the condensing or non-condensing mode for the heating of domestic dwellings or domestic dwellings in commercial premises by the circulation of heated water in open or closed systems. This standard does not apply to: boilers with a rated input of over 70kW; or groups of boilers with individual ratings of 70kW or less, but with aggregate inputs of over 70kW as specified in BS6644. NOTE1 Groups of boilers with individual ratings of less than 70kW, but with a maximum aggregate input of ≤70kW, may be installed to this standard but specialist advice on the system design, installation and control needs to be sought from the appliance manufacturer. It is not applicable to the detailed design and installation of the whole heating system, which is specified in BSEN12828, BSEN12831:2003 (incorporating corrigendum January 2009) and BSEN14336:2004 (incorporating corrigendum January 2009). NOTE2 With the publication of BSEN12828, BSEN12831 and BSEN14336, BS5449 has been withdrawn. These Standards are not aligned to UK design and installation practices; they cover commercial as well as domestic heating systems and exclude hot water. Consequently, these standards include UK national annexes covering all the relevant material from BS5449. NOTE3 The installation of boilers with a rated input greater than 70kW is covered by BS6644. Additional requirements for the installation of back boiler units are specified in BS5871‑1 and BS5871‑2. This standard applies to boilers which carry a CE mark and also to previously-used boilers which do not carry the CE mark (see 6.2.1). NOTE4 In this standard, heat input is expressed in terms of net calorific values (CV), unless stated otherwise. The ratio of gross to net heat input is approximately 1.11:1 for natural gas, 1.09:1 for propane, and 1.08:1 for butane. NOTE5 It is essential that persons carrying out the installation of any gas appliance are competent to do so. Clause4 gives information on competence. NOTE6 Some clauses of this standard might be appropriate for the installation of pool and spa heaters. The manufacturer’s instructions might advise which parts are not appropriate. For example, for direct spa and pool heaters, no corrosion inhibitors or chemical cleaning are permitted. NOTE7 The general installation requirements for 3rd family installations specified by this standard also apply to gas installations supplied with LPG/air mixtures used in the Channel Islands or the Isle of Man, providing: any gas equipment being installed has been appropriately converted and is suitable for the gas being supplied, and the requirements of the standard do not conflict with local regulations or authorized local custom and practice.
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