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PLUMBING CONNECTION
WINTER 2015
LET’S VENT A CONCERN
T
he gas installation Standard for the safe and efficient
operation of Type A appliances and equipment is AS/
NZS 5601-2013.
This Standard, which applies in Australia and New Zealand,
is in two documents that are sold separately or as a set.
Individuals or companies carrying out gas installation
work need buy only the document relevant to their activities:
∫ Part 1 (General Installations); or
∫ Part 2 (LP Gas Installations in Caravans and Boats for
Non-propulsive Purposes).
The problem here is that some requirements relating to
safety and efficient operation of a gas appliance appear to
differ between the two documents.
One area of concern is the requirement for vents to
provide air for complete combustion, appliance cooling and
prevention of carbon monoxide build-up (CO).
NATURAL VENTILATION
Until 2014, Victoria and NSW were using AS 5601-2004,
as they did not adopt AS/NZS 5601-2010 when it was
introduced due to a number of concerns with it.
AS/NZS 5601-2010 (and now 2013) have introduced new
requirements in sizing ventilation openings.
However, aspects have remained from AS 5601-2004 and
prior editions.
The ventilation provided is to be free flowing – not as
determined by the overall size of the vent itself that would
include louvres. There must be unrestricted ventilation
openings as sized by the example calculations in Part 1 and
provided by the vent openings described in the Standard:
“The minimum dimension of any free ventilation opening
shall be 6mm to minimise linting.”
Vents should have a minimum 6mm opening to prevent
linting, and when sizing the vent it must equal the free space
as provided by the 6mm openings, not the overall vent size.
Part 2 of the Standard relating to LP gas installations in
caravans and boats is different in one area, yet ventilation in
normal circumstances is classed as natural gas installation.
As required in Part 1, the ventilation required in a caravan
or boat must have free, unrestricted ventilation openings as
sized by the example calculation detailed in Part 2.
What is not detailed in Part 2 Clause 7.3.1 in relation
to ventilation is the requirement of the free ventilation
openings to be a minimum of 6mm to resisting linting.
From my memory of working with past editions of the
Standard, no reference was ever made to having 6mm free
and unrestricted ventilation openings in caravans or boats.
At times, this caused quite a bit of conjecture.
Without the minimum 6mm openings in the vent, there
is potential for linting and restricting the free flow of air
necessary for safety and efficiency, thereby compromising
the Standard.
For reasons only members of the committee that
compiled AS/NZS 5601 2010-2013 can explain, the example
calculation for Clause 7.3.1 comes out of left field in relation
to what has been a safety requirement for decades – free air
flow for ventilation openings.
The example calculation is quite bizarre in that it states:
“The use of louvres and/or mesh screens will reduce the free
area of an opening.”
Then quite innocuously the last sentence reads “where
mesh is used, the area should be doubled”.
THE SAFETY AND EFFICIENCY OF GAS APPLIANCES ARE BEING COMPROMISED BY AN ANOMALY IN THE STANDARD.
ROBERT LAMBIE
SPELLS IT OUT.
Vents to have a minimum 6mm opening to prevent linting
and when sizing the vent it is to equal the free space as
provided by the 6mm openings not the overall vent size.
GAS MATTERS
ROGER LAMBIE
VENT OPENING
6MM