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Open flue gas heaters – FAQs

ESV and the Victorian Building Authority (VBA) recommend that all gas water heaters, space heaters and central heaters are serviced at least every two years by a qualified gasfitter endorsed to carry out Type A Gas Appliance service work.

Find your local registered gasfitter by searching online or via the VBA’s website.

What is a qualified gasfitter?

All registered and licensed gasfitters are issued with a photo ID card that lists the type of work they are allowed to do. All practitioners should carry this ID and you can request to see it at any time.

Check that the qualified gasfitter is endorsed to service Type A gas appliances (their photo ID will include this information) and has the training to detect carbon monoxide spillage.

You can also check if a gasfitter is licensed or registered online, using the Victorian Building Authority directory.

How do I find a qualified gasfitter?

Find gasfitters as you would any tradesperson. Search online or via other trade directories such as the Yellow Pages, the Victorian Building Authority website or classified ads from your local newspaper.

What should a service include?

The inspection and maintenance of an appliance is to ensure your gas appliance is maintained in good and safe working order. A service should include carrying out a visual inspection of the appliance and flue system, conduct a negative pressure and combustion spillage test (CO test), internal cleaning, the repair or replacement of parts and operation of the appliance to ensure it is operating correctly and safely.

How much does the service cost?

The cost of a service will vary depending on the type of appliance, the gasfitter, the location of the appliance and a range of other factors. The best option is to look online or in the Yellow Pages and contact a few gasfitters to get a range of prices.

Will the gasfitter provide me with a certificate of compliance or documentation once the service is complete?

Not unless the value of the work exceeds $750. For further information please contact the Victorian Building Authority.

What is a flue?

Adequate ventilation and proper flueing are essential for the safe and efficient operation of gas appliances.

Flues work on the principle that hot air is lighter than the surrounding air, so a flue allows the combustion products out into the open atmosphere, rather than spill out of the draught diverter and into the room.

Gas space heaters are classified based on how this fluing is achieved. There are three categories for gas space heaters: flueless heaters, room sealed heater and open flued heaters.

What is a flueless (or unflued) heater?

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.

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.

What is 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 living 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.

What is an open flue heater?

Open flued heaters draw air from the room to feed the fire and direct combustion products outside via a flue. Inadequate ventilation and use of exhaust fans can draw carbon monoxide (and other exhaust gases) back into the room in certain circumstances.

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.

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.

To identify whether your gas heater is open flued, you must contact the manufacturer or a qualified gasfitter.

Energy Safe Victoria has compiled a list of certified open flue space heaters based on information provided by the five certification bodies.

Open flue heaters vs room sealed heaters

Many internal domestic gas heaters and appliances are designed to operate with one of two common types of flue:

  • an open flue, which is fitted through the ceiling and roof
  • a room sealed flue, which is usually fitted through the wall.

The best way to determine whether your heater is room sealed or open flue is to contact the manufacturer and provide them with the brand and model of your heaters.

I have a ducted gas heating system. Is this still an issue?

Some ducted heaters are open flued and can be affected by negative pressure if there is insufficient ventilation.

This can apply to ducted heaters where the appliance is installed indoors (for example in a cupboard) and if there is ‘negative pressure’ can affect the operation of ducted heater. The air ducts around the house that deliver hot air are not affected by the operation of exhaust fans.

It is recommended that ducted heaters are serviced every two years and during this period a CO test should be conducted at the heating vent outlets in all rooms.

I have a ducted gas heating system and the unit is outside / inside my roof. Is this an issue?

No. Ducted heaters installed outside or within roof spaces are not adversely affected by the operation of exhaust fans.

However, it is recommended that these appliances like all other gas appliances are serviced every two years.

The service should include a CO test at the heating vent outlets in all rooms.

I have a fireplace. Is this an issue?

For a fireplace using solid fuel (e.g. wood) you should ensure that smoke is drawn into the chimney and discharged to the outside atmosphere even when exhaust fans are in operation.

For a gas fuelled burner assembly in a fireplace, permanent ventilation should have been installed by the installing gasfitter.

If in doubt, engage a licensed gasfitter to check that permanent adequate ventilation is installed and that the appliance is not adversely affected by the operation of exhaust fans.

I am a tenant. Is it my landlord/agent’s responsibility to service my gas heater every two years?

The Residential Tenancies Act 1997 requires a landlord to ensure that rented accommodation is maintained in “good repair”. This includes all gas and electrical appliances provided by the landlord, which must be safe to use and properly maintained.

Find more information in our Landlords, agents and tenants brochure. Alternatively, contact Consumer Affairs Victoria for more information.

My landlord won’t respond to/refuses my request to have my gas heater serviced. What do I do?

If you are unhappy with the response from your landlord or tenant, contact Consumer Affairs Victoria for more information.

I live in public housing. I had a gasfitter service my gas heater and disconnect it. I am still waiting for a new heater/reconnection. Who do I contact?

Contact the Department of Health and Human Services for further information.

I am looking to purchase a carbon monoxide alarm. Are they reliable?

Carbon monoxide alarms can be a useful back-up precaution, but should not be considered a substitute for the proper installation and maintenance of gas heating appliances.

What to consider

If you are considering purchasing one or more carbon monoxide alarms, remember to:

  • select alarms that meet US or EU carbon monoxide standards, including recommendations for use and installation. To identify these alarms, either the packaging or the alarm will indicate that it complies with one of the following standards:
    • UL2034 (US) or
    • EN50291 (EU)
  • select alarms that provide visual and audible alarms indicating when the electrochemical sensor or battery has expired. While these alarms may provide an indication of the presence of carbon monoxide, their effectiveness is limited to the location where they are installed, as carbon monoxide levels elsewhere in the room may vary.

Similarly:

  • if you purchase a hard-wired alarm, it must be installed by a licensed electrician
  • if you are installing a battery operated CO alarm, ensure you follow the manufacturer’s installation instructions which should detail where the alarm should be located.

Be aware that CO alarms do not work in the same way as smoke alarms. Because carbon monoxide is a gas it forms pools, which could be away from where the alarm is located.

Read more on CO alarms – Gas Information Sheet No 36: Carbon monoxide alarms for domestic use