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Carbon monoxide from gas heaters
Any gas heater can spill carbon monoxide if it is faulty, poorly ventilated or not maintained, and you will not smell it. Energy Safe Victoria recommends a service by a qualified gasfitter at least every two years, with a carbon monoxide alarm as a back-up rather than a substitute.
General information, not medical advice. The health advice below is summarised from Victoria’s Department of Health. Healthdirect, the national health advice service, says that for a medical problem you can call it on 1800 022 222, and that if you need urgent medical help you should call triple zero (000) straight away.
Most of this page draws on two Victorian sources: it quotes Energy Safe Victoria and summarises the Victorian Department of Health. The rules about heater types and rentals given here are Victoria’s; other states’ rules may differ.
What carbon monoxide is
Energy Safe Victoria describes carbon monoxide (CO) as “a poisonous, colourless and odourless gas” that “interferes with the blood’s ability to carry oxygen”. It says well maintained, correctly ventilated gas appliances produce minimal CO, and high levels can occur when an appliance is faulty or not maintained, a flue is partly or totally blocked, or an appliance is installed somewhere without adequate ventilation.
Its list of heaters that can spill CO is broad: “old and new heaters, central heating units, space heaters, wall furnaces and decorative log fires”.
Open-flued and room-sealed heaters
The way a heater gets its air and gets rid of its exhaust matters most. Energy Safe Victoria sorts gas space heaters into three kinds: flueless, open-flued and room sealed.
- An open-flued heater “draw[s] air from the room to feed the fire”.
- Exhaust goes up the flue, “fitted through the ceiling and roof”.
- Through the draught diverter, exhaust can spill back into the room if the flue is blocked or there is negative pressure.
- An exhaust fan, such as a rangehood or bathroom fan, can create that negative pressure.
- A room-sealed heater draws “air from outside the house to feed the fire”.
- Its exhaust is “flued outside the room via separate ducts”, usually through the wall.
Energy Safe Victoria says open-flued heaters “can spill carbon monoxide more easily than other types of heaters”, and that “negative pressure can occur when there isn’t enough ventilation in the home and an exhaust fan is operating”, drawing air in through flues and chimneys. Room-sealed heaters, it says, “have a very low risk of adverse combustion products entering the home”. To find out whether your heater is open-flued, it says to contact the manufacturer or a qualified gasfitter.
In Victoria, Energy Safe Victoria prohibited the sale of old open-flued gas space heaters without safety shutdown features, second-hand ones included, from 1 August 2022. Heaters built to the newer standard switch off automatically if combustion products spill for more than 15 minutes; once one has shut down, a gasfitter is needed to make the installation safe and reset it.
Energy Safe Victoria’s list for using a gas heater
In its own order:
- Get a qualified gasfitter to service your heater at least once every two years (their licence can be checked online).
- Check if your heater is affected by a safety alert.
- “Ensure adequate ventilation in your home”: keep permanent ventilation clear, and leave a window open if necessary, especially with an open-flued heater.
- Don’t run a kitchen rangehood or bathroom exhaust fan while the heater is on.
- “Don’t leave your gas heater on overnight, or for extended periods.”
- Check for changes in how the heater runs, such as the flame changing from its usual colour; if anything changes, you must get a qualified gasfitter to inspect it for CO leakage. Energy Safe Victoria adds: “If your heater is old, or hasn’t been serviced for several years, consider replacing it.”
- “Install a carbon monoxide alarm as a back-up measure.”
- “Know the symptoms of CO poisoning and act quickly if you notice them.”
And what not to do:
- “Do not bring outdoor gas appliances inside your home, caravan, car or tent.”
- “Do not attempt to fix your gas heater yourself – gas work is not a DIY project (you must call a qualified gasfitter)”.
- “Do not use gas appliances for purposes other than their intended use e.g. do not use a gas cooker, cooktop or oven as your heater.”
For an open-flued heater, Energy Safe Victoria also says to keep plants and animal nests clear of the flue’s outdoor end, which “can block the flue and push CO back into the house”.
Symptoms, and what Victoria’s health department says to do
Victoria’s Department of Health says breathing in carbon monoxide may cause symptoms such as tiredness, shortness of breath, headaches, dizziness, nausea, weakness, confusion or chest pain. It names children, pregnant women and unborn babies, older people, and anyone with asthma or another long-term illness as being at increased risk.
Its advice, in summary: if you think carbon monoxide from a gas appliance may be affecting you, turn the appliance off straight away and open the doors and windows to air out the area. Then leave the property, keeping the doors and windows open if you can, and get medical advice straight away or call NURSE-ON-CALL, available 24/7, on 1300 60 60 24. Call 000 in an emergency.
The Victorian Department of Health lists NURSE-ON-CALL among Victoria’s urgent care services, so that number is for Victoria.
Carbon monoxide alarms
Energy Safe Victoria’s information sheet on CO alarms says there is no Australian standard covering them for homes, and suggests choosing one certified to EN50291 (the European standard) or UL2034 (the US standard). It says alarms “only detect CO gas”, not smoke, fire or other gases, and “only indicate the presence of CO gas at the sensor”.
On placement, it says to make sure the alarm “is audible from all sleeping areas”, and that manufacturers suggest putting alarms in or near every room with a gas heating appliance, following the manufacturer’s instructions. It lists places to avoid, including close to a gas cooking appliance, in a damp area or directly above a sink, and behind curtains or furniture. Electrochemical sensor alarms have “a limited life span of around 2 to 7 years”.
Hard-wired alarms “must be installed by a licensed electrician”. Energy Safe Victoria’s heating page adds that a carbon monoxide alarm “will help but should never be a substitute for regular servicing”.
If you rent in Victoria
Energy Safe Victoria says that under Victoria’s rental laws, which came into effect on 29 March 2021, “your rental provider must ensure a gas safety check of all gas installations and fittings on the premises is conducted every two years” by a gasfitter endorsed for Type A gas appliance servicing. The guide to servicing gas appliances covers what a service includes.