NZ Plumber October-November 2023

The Plumbers, Gasfitters & Drainlayers Board (PGDB) is aware of a recent incident where a flue cowl of a gas appliance was interfered with during roofing work, which ultimately led to a case of carbon monoxide poisoning. To keep the public safe, the PGDB provides the following guidance when working with flue cowls.

Guidance on removal of flue cowls/terminals

Removing the flue cowl of a gas appliance must be done by a licensed gasfitter. A gasfitting certificate must be issued by a licensed Certifying Gasfitter.

The flue cowl is important as it affects the flow of air and products of combustion. This has a direct correlation to how well an appliance works, as it affects combustion

conditions inside the appliance. Further, incorrect removal (or installation) of a flue cowl can cause damage to the connected gas flue or appliance, risking leaks.

It’s often thought the biggest risks associated with gasfitting relate to fire and explosions. However, the public are also at risk of injuries due to an excess of carbon monoxide (CO) and carbon dioxide (CO 2 ) from inadequate or incorrectly installed flueing and/or ventilation.

Where appropriate, gasfitters should test levels of carbon monoxide and carbon dioxide in the dwelling to ensure that there is adequate ventilation.

Following all maintenance work, including reinstalling a flue cowl, gasfitters must always re-commission the appliance in line with the manufacturer’s instructions.

• AS/NZS 5601.1:2013 clause 2.2.8 requires commissioning (note a 2022 version of the standard is out but 2013 is still the cited version)

• AS/NZS 5601.1:2013 clause 6.11.4 outlines what commissioning shall include.

Where a gas appliance does not have manufacturer’s instructions on commissioning, or the manufacturer’s instructions do not include commissioning details, AS/NZS 5601.1:2013 Appendix O provides guidelines for commissioning.

For a sealed appliance, always check all seals of the appliance and ensure there is no spillage of products of combustion into the dwelling.

Proper commissioning ensures:

• the installation is safe and proper operation of gas appliances

• there are no excess products of combustion entering a dwelling.