Flues

Question 1

State the TWO effects of excessive heat loss on the operation of a natural draught gas flue.

Answer 1

• Reduces the motive force of the flue products.

* Causes condensation.

Question 2

Give FOUR factors other than heat loss that determine the diameter of a gas flue

Answer 2

• The heat output of the appliance.
• The spigot size
• Lateral run.
• Number of elbows and bends.
• Total length of the flue.

Question 3

Give TWO factors that affect heat loss of a gas flue.

Answer 3

• Single or double skin / flue material.
• Location/position of the flue.
• Termination point.
• Length of flue.
• Elbows or bends.

Question 4

AS/NZS 5601 Part 2 gives the purpose of ventilation of compartments where gas appliances are installed.
Give TWO conditions the ventilation is designed to prevent.

Answer 4

• Wind-actuated self-trimming cowls.
• Rotary exhauster heads.
• Interlocked, fan assisted ventilation.

Question 5

A notifiable incident is classed as a notifiable event.

Give the other TWO occurrences that are classed as notifiable events.

Answer 5

• Notifiable illness or injury.

* Death.

Question 6

Cited standards
Meaning:
Example:

Answer 6

standards which have been pre-approved
as acceptable solutions or verification methods.
AS/NZS 5601

Question 7

Compliance documents
Meaning:
Example:

Answer 7

Publications that provide means of compliance.

NZ5601 Part 1, Building Code clauses.

Question 8

A new appliance is to be added to an existing installation.
The installation has an operating pressure of 5.0 kPa.
State the types of pressure tests required to be performed throughout the course of the
work, giving the test pressure for each.

Answer 8

• Leakage test. 5 kPa
• Pipework test on new pipework. 7.5 kPa
• Installation or leakage test. 5 kPa
• Final connection test. 5 kPa

Question 9

The gas installation operating pressure for an existing installation is to be increased from
1.8 kPA to 3.5 kPa.
List the required checks or tests that should be carried out during the process of changing
the pressure.

Answer 9

• Retest the pipework at higher pressure.
• Check the appliance regulators are rated for the pressure increase.
• Check the appliance operating pressures/re-commission.

Question 10

A natural gas appliance is to be converted to operate on LPG.
List SIX items that must be checked and that may need changing in the conversion.

Answer 10

• Data plate.
• Aeration.
• Operating pressure.
• Regulator.
• By-passes.
• Injectors.

Question 11

An installation is being converted from LPG to natural gas.
Give TWO aspects of the installation pipework that must be checked and that may need
changing.

Answer 11

• Size/diameter.

* Labelling.

Question 12

A builder doing renovation work has requested that a metal pipe, which the builder believes
to be a copper gas pipe, be repositioned.
Give FIVE actions to be carried out before the pipe is cut.

Answer 12

• Inform the occupier that the gas supply will be turned off.
• Test the existing installation for leakage.
• Turn the gas supply off.
• Positively identify the pipe.
• Fit an earth bonding strap.
• Purge the pipe.