This British Standard specifies the installation requirements for direct and
indirect gas-fired forced convection air heaters for space heating that are
designed for commercial or industrial applications and to which The Gas
Appliances (Safety) Regulations 1995 [1] apply.
This British Standard applies to the installation and maintenance of appliances
that are designed to utilize gases of Group H of the 2nd family (e.g. natural
gas), gases of Group P of the 3rd family (e.g. propane) as well as gases of
Group B of the 3rd family (e.g. butane) when supplied under the conditions of
the third family pressure couple (see BS EN 437:2003+A1:2009).
NOTE 1 This British Standard does not specifically cover LPG/air for which additional
requirements might be necessary.
This British Standard applies to the installation of direct gas-fired air heaters
within the scope of BS EN 525:2009 and to indirect gas-fired forced convection
air heaters within the scope of BS EN 621:2009, BS EN 1020:2009 and, where
appropriate, BS EN 1196:1998. These standards cover air heaters having a net
heat input not exceeding 300 kW. This standard also applies to the installation
of direct gas-fired air heaters within the scope of BS 5990:2006 and to indirect
gas-fired forced convection air heaters within the scope of BS 5991:1998. These
standards cover air heaters having a gross heat input greater than 330 kW but
not exceeding 2 MW (1.8 MW net).
NOTE 2 For the purposes of this British Standard, installation includes design,
inspection and commissioning. It is recognized that each of the tasks can be
performed at the same time by different persons.
NOTE 3 The ratio of gross to net heat input is approximately 1.11:1 for Group H
(natural gas), 1.09:1 for Group P (propane) and 1.08:1 for Group B (butane).
NOTE 4 The ventilation rates in cm2/kW of heat input given in this British Standard
are based on the net calorific value.
This British Standard also applies to air heaters designed to supply make-up air,
door curtain heaters, transportable air heaters and heat exchange modules (i.e.
air heaters without a main air movement fan) where such heat exchange
modules are used in environmental non-process applications such as air handling
units. It also covers installation of heaters in areas where petroleum or other
flammable heavier-than-air vapours can be present (see 5.1.2).
It does not include the safety requirements for installation where flammable
dusts, toxic gases or flammable lighter-than-air gases might be present in
significant quantities.
NOTE 5 In such cases it is important that liaison takes place with the Health and
Safety Executive.
This British Standard does not apply to the installation of air heaters to which
The Gas Appliances (Safety) Regulations 1995 apply, or that are designed for
the sole use in domestic premises.