This British Standard specifies requirements for the selection,
installation, inspection, commissioning and maintenance of gas?fired
boilers for central heating and other purposes, which have a total
rated heat input not exceeding 70 kW, 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 70 ? kW;
? groups of boilers with individual ratings of 70 kW or less but with
aggregate inputs of over 70 kW as specified in BS 6644.
NOTE 1 Groups of boilers with individual ratings of 70 kW or less but
with aggregate inputs of less than 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
heating system, which is specified in BS 5449.
NOTE 2 With the publication of EN 12828, EN 12831 and EN 14336 it is
necessary for BS 5449 to be declared obsolescent and to be withdrawn
within two years. 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 are being amended to include
national annexes covering all the relevant material from BS 5449.
NOTE 3 The installation of boilers with a rated input greater than 70 kW
is covered by BS 6644. Additional requirements for the installation of back
boiler units are specified in BS 5871?1 and BS 5871-2.
This standard applies to boilers which carry a CE mark and also to
previously used boilers which do not carry the CE mark (see 4.2.1).
NOTE 4 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 5 It is essential that persons carrying out the installation of any
gas appliance be competent to do so. Annex A gives information about
the legal requirements which relate to approved operatives and gas
appliances.
NOTE 6 Some parts of this standard might be appropriate for the
installation of pool and spa heaters. The manufacturer’s instructions may
advise which parts are not appropriate. For example, for direct spa and
pool heaters, no corrosion inhibitors or chemical cleaning are permitted.