BS 6644:2011

What is this standard about?

It provides guidance on how to safely install and maintain gas-fired hot water boilers.

Who is this standard for?

Gas-fired hot water boiler manufacturers, installers, engineers and users.

Why should you use this standard?

It specifies requirements for the installation – including design, inspection, commissioning and maintenance – of gas-fired hot water boilers of net rated heat inputs exceeding 70 kW but not exceeding a net heat input of 1.8 MW. Groups of boilers with individual net heat inputs of 70 kW or less, but with aggregate net heat inputs in excess of 70 kW, are also covered.

This standard applies to the installation of boilers that are designed to utilize normally distributed gases of Group H of the second family (e.g. natural gas), and gases of Group P (e.g. propane) and Group B (e.g. butane) of the third family. For the purposes of this installation standard, LPG/air mixtures are regarded as third family gases. It applies to the installation of the following gas-fired hot water boilers:

• Boilers supplied as a complete assembly and conforming to BS EN 656 or BS 5978 (all parts)
• Boilers supplied as a complete assembly and used in multiple boiler installations where the total net heat input exceeds 70 kW and conforming to BS EN 297, BS EN 483 or BS EN 677
• Boilers and burners delivered separately and assembled on site, comprising:

1. a boiler shell conforming to BS EN 303-1, BS EN 12952 (all parts), BS EN 12953 (all parts), BS 779, BS 855 or BS 2790
2. a burner conforming to BS EN 676
3. an assembly conforming to BS EN 303-3 or BS 5987-1 and BS 5978-3

What’s changed since the last update?

This is a full revision of BS 6644:2005+A1:2008. It introduces the following principal changes:

• System requirements in accordance with BS EN 12828 have been added
• Details on condensing appliances and condensate removal have been added
• The appliance classification types have been updated