• Gas Bayonets and Gas Vents in WA – What Why Where and When

    26 Jun, 2017 | 1,035 views

    Fuel-less heating impacts to consider when buying an existing home or building a new home without gas vents.

    1.    What

    A gas bayonet is basically a tap installed into the wall where you can draw gas to fuel an internal heater, generally a flue-less heater (I.e. no chimney to the external air).

    2.    Why Flue-less Heaters?

    A flue-less gas space heater is a gas appliance that does not have a flue to collect and exhaust fumes to an outside area. The fumes are the products of combustion that result from burning gas in the appliance.  This type of appliance releases all the combustion products directly into the room it is heating.

    3.    So What is the Problem?

    The combustion products produced by flue-less gas heaters include a number of pollutants such as nitrogen dioxide and carbon monoxide, which can be harmful to health.  Water vapour is also produced and can directly affect health by increasing the growth of moulds and dust mites.  The amount of air pollutants produced by a flue-less gas heater can vary depending on the size and type of heater, its installation and how well it has been maintained.  The level of air pollutants in the room will also vary depending on the way in which the heater is used, the size of the room and the amount of fresh air that enters the room through fixed ventilation openings.

    Potential health effects of indoor air pollutants

    Flue-less gas heaters are known to increase the level of pollutants inside a home.  Recent research has found that at high levels, these pollutants can increase the incidence of symptoms in some people with respiratory sensitivities. People with asthma are particularly susceptible to increased levels of indoor air pollutants and may experience asthma symptoms more often.

    See info from the Dept of Health (WA) http://www.health.wa.gov.au/publications/documents/Health%20Concerns%20of%20Unflued%20Gas%20Heaters.pdf

    4.    What is the Solution?

    Simple Vents! Gas vents in the bottom of the wall and at the top of the wall or in the ceiling.

    The purpose of these vents is to pull in fresh air and expel the stale air containing the fumes from the flue less heater. Clean air means you don’t get sick!  The downside is you do get a bit of a draft in the room but it won’t make you ill.

    5.    Are Gas Vents important?

    Remember you are also answering this question on behalf of babies and children so the obvious answer is yes!

    The Government thinks so too, and has passed many laws and regulations that now make low and high gas vents mandatory for all new homes fitted with gas bayonets.  There are also Australian Standards on the issue.

    6.     So it’s Simple, Right?

    Sadly no. There is a multitude of rules, regulations and standards on this issue which has the wonderful ability to make a simple subject very complex.

    As a quick Guide from the WA Dept of Commerce notes when using a flue-less heater:

    1. Keep the room well ventilated. If the room is fitted with a gas bayonet fitting to allow the connection of a flue-less gas heater, then by (current) law two permanent ventilation openings must be installed. The vents must connect to the outside of the building and one vent must be installed at low level and the other vent at high level.
    2. The physical external dimensions of each vent should be not less than the equivalent of 310 mm x 170 mm (to provide for a minimum open area of 25,000 square mm based on the vent design having an open area of 48%).
    • Never use a flue-less gas space heater in a bedroom, bathroom or in a caravan. (Note: Flue-less gas space heaters are being phased out of use in child care centres and all types of schools, to avoid the lengthy exposure of children to the emissions produced).
    1. Do not use the gas heater unless it has been certified for use by the Australian Gas Association or SAI Global (check for label or badge attached), or if the gas consumption of the heater exceeds 25 MJ per hour.
    2. Make sure that air volume of the room in which the heater is used is at least 30 cubic metres (for example: 3.5 m x 3.5 m with a 2.4 m high ceiling).
    3. Follow the manufacturer’s instructions for the use of the gas space heater. Have each flue-less gas space heater serviced by a qualified person once every two years. A poorly maintained gas heater, together with inadequate ventilation, may contribute to high levels of pollutants.

    Bottom line is you should have high and low vents. There are a myriad of additional requirements that then need to be considered including the size of the room, size of the vents etc.  When in doubt check with a WA Licenced Gas Fitter.

    7.    So what is the Problem? – Older Homes

    While the current rules are clear, yet complex, they have not always been this clear. At various times in history there were occasions when, no vents were required, low vents were only required, then high and low vents. Problem is the dates when these rules changed are not so clear!

    So if you are buying an older home it may or may not have the right number of vents in the right location in rooms which has a gas bayonet.

    Vents can be retrofitted to older homes – make sure the right size is used.

    8.     So what is the Problem? – New Homes

    So the rules are clear now – put a bayonet in and you need high and low vents – simple. So why do so many builders/plumbers forget to install them? That’s why you need an independent building inspector.

    9.    In Summary

    Gas bayonets provide you with another way to heat the home using flue-less heaters. Gas suppliers even suggest it’s cost effective.  Flue-less heaters produce nasties that you (and your kids!) do not want to breathe too much of. So the Government generally wants your home to have high and low gas vents in the room that has a gas bayonet so the room can vent the by-products of the heater.

    If you build a home today, it basically will have to have high and low gas vents to keep you safe. If you already have or are  buying an older home, because it may have been built under older regulations, it may not need to have high and low vents, but the health risks are the same. So give consideration to installing extra gas vents if you are going to use a flue-less heater.

    10.     Need More Info

    Further information on this subject may be obtained from relevant gas appliance manufacturers or their local representatives. EnergySafety’s website also has additional information on this subject. energysafety@commerce.wa.gov.au

    11.  References

    WA Dept of Commerce:





    Australian Standard AS 5601.1 2010

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