BS 5546:2010

This British Standard specifies requirements for the selection, installation, inspection, commissioning and maintenance of gas-fired water-heating appliances, which have a rated heat input not exceeding 70 kW, based on net calorific value.

It applies to water-heating appliances utilizing 1st, 2nd or 3rd family gases designed to operate in the condensing or non-condensing mode for the supply of hot water for domestic purposes in domestic dwellings or domestic dwellings in commercial premises.

This standard does not apply to:

1. water-heating appliances with a rated input of over 70 kW;

2. hot water supply systems in multiple dwellings supplied from a central source.

NOTE 1 Groups of water-heating appliances with individual ratings of less than 70 kW but with a maximum aggregate input of 70 kW 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 does not cover the detailed design and installation of the whole hot water distribution system, which was specified in BS 5449.

NOTE 2 With the publication of EN 12828, EN 12831 and EN 14336, BS 5449 has been withdrawn. These European standards, which have now been adopted as British Standards, are not aligned to UK design and installation practices; they cover commercial as well as domestic heating systems and exclude hot water. Consequently, they have been amended to include national annexes covering all the relevant material from BS 5449.

This standard applies to water-heating appliances which carry a CE mark and also to previously used water-heating appliances which do not carry the CE mark (see 5.3.1).

NOTE 3 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.

NOTE 4 It is essential that persons carrying out the installation of any gas appliance be competent to do so (see Clause 4).

NOTE 5 Some parts of this standard might be appropriate for the installation of pool and spa water-heating appliances. The manufacturer’s instructions may advise which parts are not appropriate.

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