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Gas news
CO risk puts open flue under review
By Jason Treseder , Senior Gas Engineer
Energy Safe Victoria is currently undertaking a review of open flued gas heaters ( refer to page 7 ).
This follows a number of reported incidents where open flued heaters were found to be spilling high levels of carbon monoxide into the living areas of homes , particularly under negative pressure conditions caused by the operation of exhaust fans .
At this stage , the review is examining space heaters and decorative effect appliances that incorporate a draught diverter .
What is an open flued heater ?
To produce heat , gas heaters burn gas and air , and emit combustion products like carbon monoxide and carbon dioxide that need to be released through a flue .
Gas space heaters are classified based on how this fluing is achieved . There are three categories for gas space heaters : flueless heaters , room sealed heaters and open flued heaters .
Flueless Heaters
Flueless heaters draw combustion air from within the room and emit combustion products back into the same space where the heater is located .
These heaters require ongoing ventilation to external spaces to allow fresh air to fuel the burner and discharge combustion products .
As combustion products are by design released into the living area , there are strict limitations on carbon monoxide and nitrogen oxide emissions , as well as requirements for a safety
Product recall : BV20-F ball valve
By Jason Treseder , Senior Gas Engineer , Type A Gas Appliance and Component Safety
device to shut off the burner if levels of oxygen drop too low .
Note that indoor flueless heaters are restricted in Victoria . Regulations prohibit the installation of new indoor flueless heaters , with the exception that existing LPG flueless heaters may be replaced in limited circumstances .
Gas heaters intended for outdoor use only have different requirements .
Heaters designed for outdoor use must never be brought indoors or in an unventilated location like a caravan or tent .
Room Sealed Heater
Room sealed heaters , as the name implies , have a combustion circuit that is completely sealed from the living area .
All air drawn in for combustion and all products of combustion emitted , are flued outside the room via separate ducts . This means ventilation is not required for the room and room exhaust fans do not affect the safety of the heater . These appliances have a very low risk of adverse combustion products entering the home .
Open flued heaters
Open flued heaters are the last category of heater . They draw air for combustion from inside the room and direct combustion products outside via a flue .
Its design means the combustion circuit is exposed to air pressure from within the room at the burner inlet , and at the flue terminal outside .
Consequently , factors such as wind or the use of appliances including bathroom exhaust fans can lower the air pressure inside the room .
If the negative pressure is high enough , airflow
through the flue may become restricted or in some cases even reversed .
If the supply of fresh air to the burner is interrupted , the flame will produce high levels of carbon monoxide .
To ensure the burner is not affected by changes in the flue , many natural draught open flued heaters are fitted with a draught diverter .
The draught diverter is an opening in the flue that allows combustion products to spill into the living area in the event the flue is blocked or there is a negative indoor pressure .
When the flue is operating correctly , the hot combustion products travelling up the flue will suck combustion products straight past the draught diverter opening to outside .
However , when there is a fault the draught diverter is designed to automatically redirect combustion products into the living area without interrupting airflow to the burner and without producing excessive carbon monoxide .
Therefore , the room in which the heater is installed requires ventilation to provide replacement air used by the heater , and prevent negative pressures from exhaust fans from affecting the normal operation of the heater .
Gasfitter responsibilities
Gasfitters are required to test heaters during installation and service to ensure it does not spill combustion products and any exhaust fans do not affect the heater .
ESV recommends all gas heaters are serviced by a licensed gasfitter at least every two years .
For more information on any of the above please contact the ESV technical helpline on
1800 652 563 .
On 3rd November 2014 , Australian Valve Group Pty Ltd issued a recall for its BV20-F ball valve sold between 1 May 2013 and 31 October 2014 .
The hazard identified is that some valves may not stop gas flow when the valve is closed .
While there have been no recent incidents reported , the nature of the issue means the fault is not obvious and may remain undetected until the valve is used .
ESV is reminding gasfitters to check gas valves and confirm if they are part of the recall .
What to look for Affected valves are marked with batch codes : »»
B4 , B5 , B6 , B7 , B8 , B9 . B0 . BN , BD
»»
C1 , C2 , C3 , C4 , C5 , C6 , C7 , C8 .
More information Further details on the recall are available on the ACCC website at www . productsafety . gov . au