Flued: Flued Gas Heaters vs Unflued Portable Gas Heaters

Flued refers to a flue pipe, duct or even a chimney used to convey the smoke or combustion gases from a wood, coal, oil or gas combustion device to the outdoors.

A flue conveys smoke in the case of wood or coal fires and combustion gases in the case of oil or gas fires through a wall or ceiling.  The combustion can be in a fireplace, heater, furnace, cooker, hot water heater, generator or any other combustion device, including a flued gas heater for the home.

Flue pipe configurations for gas heaters

A flued gas heater conveys combustion gases and water vapour through a chimney or flue to the outside of a home, as shown in the illustration. An unflued gas heater discharges them directly inside the home, with the possibility of causing indoor air pollution that may have deleterious health effects.

Flued gas heaters have a flue – pipe vent – to convey combustion gases from the interior of your home. Flued gas heaters are safer to run than unflued gas heaters, as no carbon dioxide, carbon monoxide water vapour and NOx stay in the room.

Gas Heater for Sale: LPG Gas Heaters and Natural Gas Heating

A gas heater for sale can include either LPG gas heaters or natural gas heating. Almost all heater models are available for both types of gas. You must select the version that matches the gas you have, as they are not interchangeable.

LPG Conversion – Natural Gas Conversion – Natural Gas to LPG Conversion Kit

If you move and your new home has the other kind of gas, you can do an LPG conversion or natural gas conversion on most current gas heater models. You would need a natural gas to LPG conversion kit or an LPG conversion kit.

Rinnai Gas Heater Models & Paloma Gas Heater Models

Rinnai is the leading manufacturer of gas heaters sold in Australia. Rinnai gas heater models include both flued gas heaters and unflued portable gas heaters. They are available as either LPG gas heaters or in natural gas heating models.

Rinnai Avenger Gas Heater

The Paloma gas heater range is a bit more limited but tends to be a bit less expensive than the comparable Rinnai gas heater models.

Advantages of Unflued Portable Gas Heaters

Unflued gas heaters, also called portable gas heaters, are typically more energy efficient, with 5.8 or 5.9-star ratings. This is because there is no heat lost through the flue.

They are also less expensive to purchase and install, as there is no hole to cut in the wall or ceiling for the flue. A flued gas heater is about 50% more expensive than a portable gas heater, as there is typically the extra cost for a power flue and flue kit.

In fact, they are also frequently referred to as portable gas heaters.  This also makes them easy to store in the off-season, whilst flued gas heaters are fixed in place.

Gas Bayonet Fitting – Gas Heater Bayonet Connection

A male gas bayonet fitting hose works as gas heater bayonet connection with a female gas bayonet socket fitting. The female gas bayonet fitting is a push & twist to lock socket for the male gas bayonet fitting. The female fitting is affixed to the floor or wall and connected to the gas supply.

Gas Bayonet Inserted into Female Wall Fitting

Portable gas heaters typically come with a gas bayonet fitting hose that allows you to move it to any room with a gas bayonet fitting installed. The gas bayonet fitting plugs into a wall or floor socket gas heater bayonet connection, as illustrated. The 3m long hose also allows for various positions and angles.

Health Issues with Unflued Gas Heaters

People most at risk to the health effects of CO and NOx include those with heart disease, infants, unborn babies and the elderly. Also, people with asthma and other respiratory diseases are particularly vulnerable to the effects of NO2 exposure. Breathing in high levels of NO2 can cause respiratory tract irritation and shortness of breath. Children may experience more frequent cold symptoms or asthma attacks if exposed over a prolonged period of time.

Nitrogen Dioxide (NO2) can be difficult to detect in your home. NO2 is an invisible and tasteless gas, however, it does have a strong acrid, ammonia-like odour.  NO2 levels will rise in a room where an unflued gas heater is in use. 

Government safety regulations specify the maximum safe levels that can be released by portable gas heaters (unflued gas heaters).

However, for most people not in one of the at-risk groups, unflued gas heaters are quite safe when you follow all of the manufacturer’s safety instructions, including providing adequate ventilation.

Victoria Special Rules for Unflued Gas Heaters

Victoria only allows certain unflued gas heaters that meet their more stringent VIC requirements. Many Rinnai gas heater models comply with these rules.

Victoria also restricts when they can be installed. It can only be as a replacement for an existing LPG unflued gas heaters. Installation of a new gas bayonet fitting is prohibited.

If you live in Victoria, your gas appliance dealer can help to explain the requirements.


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The information in this blog is retrieved from various resources and is believed to be correct when published. The information may not be error free nor applicable in all circumstances.