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 standard applies to the installation of appliances that are designed to utilize gases of Group H of the
second family (e.g. natural gas), gases of group P of the third family (e.g. propane) as well as gases of group
B of the third family (e.g. butane) when supplied under the conditions of the third family pressure couple
(see BS EN 437:2003).
NOTE 1 This standard does not specifically cover LPG/air for which additional requirements might be necessary.
This standard applies to the installation of direct gas-fired air heaters within the scope of BS EN 525:1998
and to indirect gas-fired forced convection air heaters within the scope of BS EN 621:1998,
BS EN 1020:1998 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 5990:1990 and to indirect gas-fired forced convection air heaters within the
scope of BS 5991:1989. 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 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 standard are based on the net calorific value.
This standard also applies to air heaters designed to supply make-up air, door curtain heaters and
transportable air heaters. 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 essential that liaison takes place with the Health and Safety Executive.
This standard does not apply to the installation of air heaters to which the Gas Appliances (Safety)
Regulations 1995 [1] do not apply, or that are designed for use in domestic premises.