Open flue appliances | Resources Safety & Health Queensland
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Petroleum and gas safety alert no. 83 | 22 August 2018 | Version 1

Open flue appliances

What happened?

Recent incidents in Australia have highlighted how vulnerable and sensitive gas fuelled open-flue appliances can be to changes in air movements and air pressures in the area where they are installed. The issue of changes in air movement and pressures are more prevalent in well-sealed and modern energy efficient homes.

How did it happen?

Increasing demands for more energy efficient homes has resulted in a decrease in the quantity of adventitious air, and an increase in the effectiveness of air extraction systems such as range hoods and bathroom ventilators. This has resulted in building interiors being subject to negative pressures.

Open-flue appliances rely on ‘natural buoyancy’ in the flue to create movement of the combustion products from the appliance to outside atmosphere.

Where kitchen range hoods or bathroom extraction fans cause negative pressures on the area in which an open-flue appliance is installed, the operation of the flue can be adversely affected; causing combustion products to be ‘pulled’ into the building instead of being discharged to outdoors.

In cases where an open-flue gas appliance has not been regularly maintained it can produce ‘carbon monoxide’ (CO) through incomplete combustion. Exposure to relatively small quantities of CO can cause headaches, nausea and it can be fatal.

Key issues

  • Open-flued heaters relay on natural buoyancy of hot combustion products.
  • Exhaust and extraction fans can cause negative pressures within a building.
  • Negative pressures within a building can adversely affect performance of open-flued appliances.
  • Poorly maintained gas appliances can produce Carbon Monoxide through incomplete combustion.
  • Carbon Monoxide is an odourless and colourless toxic gas that can be fatal at low quantities.
  • Open-flued heaters should be serviced and checked for correct operation prior to the winter months.

Recommendations

  • Owners of open-flued appliances should ensure they are checked by a gas work licence holder.
  • Gas work license holders should ensure they conduct the open-flue spillage test detailed in Appendix R of AS/NZS5601.1 when installing, servicing or maintaining open-flue gas appliances.
  • Gas work licence holders should advise their customers of servicing and maintenance requirements for all gas appliances.
  • Anyone installing/replacing a kitchen exhaust canopy or a bathroom extraction fan should ensure the work does not adversely affect the operation of any open-flue gas appliance.

Investigations are ongoing and further information may be published as it becomes available. The information in this publication is what is known at the time of writing.

We issue Safety Notices to draw attention to the occurrence of a serious incident, raise awareness of risks, and prompt assessment of your existing controls.

Comments

‘Adventitious air’ is the air that naturally enters a building through gaps and cracks around windows and doors.

‘Natural bouyancy’ means the natural effect of combustion products rising within a flue/chimney due to differential temperatures. “Hot air rises”.

‘Carbon monoxide’ (CO) is an odourless and colourless gas that may cause symptoms including tiredness, shortness of breath, headaches, dizziness, nausea, weakness, confusion or chest pain if inhaled.

References and further information

Authorised by Bill Date - Chief Inspector, Petroleum and Gas Inspectorate

Contact: Paul Beaumont, Principal Inspector (Gas Work) , +61 7 5459 6189

Issued by Queensland Department of Natural Resources, Mines and Energy

Safety: This information is a guide only and is issued to promote safety through experience. It is not to be taken as a statement of law and must not be construed to waive or modify any legal obligation.

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Acknowledgement of Country

RSHQ respectfully acknowledges all Aboriginal peoples and Torres Strait Islander peoples and the Traditional Owners and Custodians of the country on which we live and work. We acknowledge their continuing connection to land, waters and culture and commit to ongoing reconciliation. We pay our respect to their Elders past and present.