QUESTION 9
(a) State THREE reasons for providing ventilation for a gas fired water heater installed in a cupboard.
 1
 2
 3
(3 marks)

(b)  List, in the correct order, SEVEN steps that are required to safely purge air from a new domestic
gas installation with an open burner.
 1
 2
 3
 4
 5
 6
 7
 (7 marks)

(c)  Sketch, label and describe the appearance of a correctly adjusted pre-aerated natural gas flame.
(4 marks)

(d)  State TWO characteristics of a pre-aerated gas burner flame if the primary air inlet becomes
blocked.
 1
 2
(2 marks)

(e) Define what is meant by ‘LOCK-UP’ pressure in relation to a gas installation.
(1 mark)
Total 17 marks

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