NOTE 1 This standard assumes that a portable combustion gas analyser [often referred to colloquially as a “flue gas analyser” (FGA)] of the type specified in BS EN 50379‑3 or BS 7927:1998 incorporating Amendment No. 1:1999 is available to the gas operative and the operative is competent in its use and the interpretation of any reading obtained. This competence can be demonstrated by satisfactory completion of the relevant ACS assessments, which cover the use of electronic portable combustion gas analysers. See Clause 4 for further information on competence.

NOTE 2 BS EN 50379‑3 superseded BS 7927:1998 incorporating Amendment No. 1:1999 on 1 March 2007. However, electronic portable combustion gas analysers conforming to BS 7927:1998 incorporating Amendment No. 1:1999 remain acceptable for the purposes of this standard.

NOTE 3 A definition of a dwelling is given in 3.7.

NOTE 4 One of the main combustion products from gas appliances is CO₂, which is mainly regarded as an asphyxiant, but is also a toxic substance which could be present in the air in sufficient quantity to prove harmful. For guidance on the occupational health considerations of CO₂, reference can be made to the HSE Guidance note on Workplace exposure limits, EH40/2005 [8].

NOTE 5 Electronic portable combustion gas analysers that calculate CO₂ levels from an oxygen (O₂) measurement are:

NOTE 6 Type A, type B and type C classification of gas-fired appliances is described in PD CEN/TR 1749 and in 3.21.

NOTE 7 At the time of installation of a new appliance it is not necessary to carry out tests to measure the level of combustion products in the flue, unless the gas appliance instructions specify that a test be carried out (see 11.2).

NOTE 8 Electronic portable combustion gas analysers are not to be used as a substitute for normal service and maintenance carried out in accordance with gas appliance instructions. This standard describes the options of how they can be used in conjunction with gas appliance instructions.