Unflued gas heaters blow all combustion products of the heater into the building, unlike a chimney or flue which carry them outdoors. Such heaters have high energy efficiencies but they produce various pollutants that can harm your health. Health effects are caused by the nitrogen dioxide and carbon monoxide emitted from combustion of gas. Many States regulate to limit the size of these heaters and/or require that fixed wall vents be installed to increase the ventilation rates of the rooms where the heaters are installed.
Replacing your unflued gas heater with a flued gas heater or another unharmful heater or good ventilation will help reduce health risks associated with unflued gas heaters.
Closing doors will contain the spread of carbon monoxide and nitrogen dioxide will not help as it will create a more concentrated amount of carbon monoxide and nitrogen dioxide in the selected room.
Flued gas heaters or solar heating is a good alternative to unflued gas heating.
Australian Standard AS 5601-2002 (AG 601-2002)
Gas installation stipulates installation requirements for unflued gas heaters, which include the following:
- Unflued gas heaters are not to be installed in the following locations: bedroom; bathroom; toilet; sauna or caravan
- The maximum output rate from the heater per cubic metre of room volume will not exceed 0.4 MJ/h for a heater with a thermostat and 0.2 MJ/h for a heater without a thermostat
- The maximum output rate of all heaters in a room in residential premises will not exceed 25 MJ/h.
Additional State Regulations
South Australia
- Heater size in residential premises limited to 18 MJ/h.
- Heaters to be not larger than 18 MJ/h unless there are additional safety features.
- Requirement for two vents (high and low) sized at 10cm2/MJ/h for all heaters.
Victoria
- Unflued gas heaters are not to be installed on natural gas unless emission point for combustion products is at least 2.5 m above floor level. LPG heaters in contrast do not have requirements in addition to the installation and appliance codes.
- No additional ventilation specified by state regulations
Western Australia
- Room a minimum of 30 m3 Requirement for 2 vents per room (high and low), with 1.5 m minimum vertical separation, each with minimum free area of 250 cm2
