Unflued gas heaters have no flue and discharge the combustion gases and water vapour directly into the home. Most unflued gas heaters have a hose and bayonet fitting so it can be moved from room to room, plugged into bayonet sockets.
Unflued gas heaters have higher energy star ratings but they do vent some combustion gases inside the home. The gas levels released are specified by government safety regulations.
Flued gas heaters for the home have a flue that conveys all combustion gases and water vapour outside of your home, for cleaner indoor air. Balanced flue models draw the combustion air from outside your home, so the amount of air drawn in is balanced with the exhaust gas that goes out the flue.
Flued gas heaters burn gas to generate heat and use a flue to carry the exhaust gases away. You can get either flued gas space heaters or flued gas fireplaces. There are both natural gas and LPG flued gas heaters.
Unflued gas heaters are more energy efficient and cost less to purchase and install than flued gas heaters. (see flue diagrams above)
Australians looking to buy a gas heating will find that the available gas heaters for sale are broadly grouped as either unflued gas heaters (portable gas heaters) or flued gas heaters for the home. Both are available in either natural gas or LPG models.
What is the difference between flued vs unflued gas heaters and which one should you buy?
Here is a review of the pros and cons for you to consider when you decide on which type of heater is right for you:
Unflued Gas Heaters
Unflued gas heaters have no flue and discharge the combustion gases and water vapour straight into the room. Most unflued gas heaters can be moved between rooms, as they have a gas hose that plugs into a floor or wall bayonet socket. Some unflued gas heaters are fixed in place to the wall.
Gas Heating
Gas heating is the heating of a room or outdoor area using a gas space heater fuelled by natural gas, LPG (propane or butane) or biogas. Indoor gas heater types include unflued portable gas heaters, flued gas heaters, radiant gas heaters, convector gas heaters, radiant-convectors, and gas fireplaces.
Gas Heater
A gas heater is a space heater used for room heating or outdoor area heating fuelled by natural gas (including CNG and LNG) or LPG (propane, butane or a mixture of the two). The two general types of home gas heaters are flued gas heaters (vented) and unflued gas heaters (unvented).
Portable Gas Heaters – Flueless Gas Heater
Unflued gas heaters have no flue and release the combustion gases and water vapour directly into the home. However, unflued gas heaters are more energy efficient and cost less to purchase and install than flued gas heaters.
Most unflued gas heaters have a 3m long hose to plug them in to a bayonet socket and can be moved from room to room. These are more commonly called portable gas heaters.
Portable LPG heaters or unflued gas heaters (flueless gas heater) or are typically much more energy efficient than flued gas heaters for the home and have higher Energy Star ratings, as there is no heat loss through a flue. Portable gas heaters (unflued gas heaters) are also less expensive than flued gas heaters (flued LPG gas heaters), as they do without any flue kit and the installation is much faster with a gas heater bayonet connection.
Portable gas heaters (unflued gas heaters) have neither a flue nor a chimney. As a result, unflued heaters release some combustion gases and water vapour directly into the home.
Because flued gas heater vent the air pollutants and water vapour out of the home through a flue pipe vs portable gas heaters that release them in the home, an unflued gas heater could cause indoor air pollution that may have health effects.
The maximum levels released by portable gas heaters (unflued gas heaters) are specified by government safety regulations.
Flued Gas Heaters – Rinnai Flued Gas Heaters – Flued LPG Gas Heaters – Gas Fixed Flued Heater
A flued gas heaters directs combustion gases out of your home through a flue pipe or chimney. This means that gas fixed flued heaters do not emit combustion gas nor water vapour inside the home. They are available as natural gas and LPG flued gas heaters.
Flued gas heaters are also available in direct vent or balanced flue models that draw the combustion air from outside your home, so there are less drafts. The amount of air drawn in is balanced with the exhaust gas that goes out the flue.
Gas fixed flued heaters have a flue that conveys the combustion gases outside of your home. However, flued heaters are less energy efficient than unflued gas heaters.
Rinnai flued gas heaters are arguably the best flued gas heaters Australia and they come in flued LPG gas heaters and natural gas fixed flued heater for sale. Rinnai flued gas heaters and Paloma flued gas heater both offer multiple gas fixed flued heater models at attractive flued gas heaters prices.
Braemar offers flued gas wall heaters, which are gas wall furnace heaters with a flue or powered flue.
Some flued gas heaters (flued LPG gas heaters) have a powered flue, like the Rinnai Energysaver Gas Heater, which is a gas fixed flued heater with an electric fan driving the gases out of the home.
Flued gas heaters for the home tend to cost more than unflued gas heaters because of the extra flue hardware and installation required.
Flued gas heaters (gas fixed flued heater) for sale come in large or small flued gas heater for sale.
Be aware that gas fixed flued heater do have lower Energy Star ratings, as there is some heat loss through the flue.
Gas fitters know how to install a flued gas heater (gas fixed flued heater) and can quote you on the flued gas heater installation cost.
Learn more about the details involved with flued vs unflued gas heaters…
Indoor Emissions – Are Unflued Gas Heaters – Portable Gas Heaters Safe
The term “flued” refers to the fact that the combustion gases generated when the gas is burnt are directed out of your home by means of a flued gas heater pipe (gas fixed flued heater) through the wall or ceiling. As a result, there are no emissions in your home with flued gas heaters (flued LPG gas heaters).
The accompanying diagram shows a flued gas heaters installation example of a flue through a wall
Care should be taken when using unflued (flueless) gas heaters if the family includes very young, unborn, elderly or individuals with some medical conditions, as they may be more sensitive to the emissions.
However, for the majority of people, unflued gas heaters are quite safe when you follow all of the manufacturer’s safety instructions, including providing adequate ventilation.
Energy Efficiency & Operating Costs of Portable Gas Heaters vs Flued Gas Heaters
Portable gas heaters (unflued gas heaters) are more efficient than flued gas heaters for the home because some of the heat is lost through the flue. The typical Star Ratings for portable gas heaters (portable LPG gas heaters) are from 5.8 to 5.9 Stars, meaning that they are about 90% efficient in converting the gas to usable heat.
Flued gas heaters (flued LPG gas heaters) can have a broad range of performance, with Star Ratings from 1.0 to 4.8 Stars. Gas fixed flued heater equates to 61% to 84% efficiency levels.
This means is that you could save as much as 32% of the cost of heating by choosing portable gas heaters (unflued gas heaters) compared with some flued gas heaters – gas fixed flued heater.
Please see Energy Efficienc & Star Ratings for Gas Fixed Flued Heater vs Unflued Gas Heaters
Portability of Unflued Gas Heaters
Portable gas heaters (portable LPG gas heaters) can be moved where needed, from one room to another, as long as each room has a gas heater bayonet connection.
This is why they are commonly referred to as Portable Gas Heaters. A Rinnai gas heater or Paloma gas heater are two of the most popular brands of portable gas heaters.
The portable gas heaters plugs into the gas heater bayonet connection via a gas bayonet hose.
This also allows you to rotate the direction of portable gas heaters, to aim the heat at or away from a particular part of the room.
On the other hand, flued gas heaters are fixed in place by the gas connection and flue.
Gas Heaters & Moving Home
Portable gas heaters (portable LPG gas heaters) are much easier to take with you when you move than flued gas heaters (flued LPG gas heaters).
You simply disconnect it from the gas heater bayonet connection and go.
Moving flued gas heaters (gas fixed flued heater) requires a gas fitter to uninstall the unit and reinstall it for the new home.
There is also the issue of the flue hole in the wall or ceiling if you remove the gas fixed flued heater.
In addition, most home buyers would consider flued gas heaters to be a built-in appliance and expect it to remain with the house.
Comparison of Flued Gas Heaters vs Portable Gas Heaters Purchase Cost
Flued Gas Heaters for the home (gas fixed flued heater) are more expensive to purchase than portable gas heaters (unflued gas heaters). For example, when comparing comparably sized flued gas heaters (flued LPG gas heaters) and portable gas heaters (unflued gas heaters) from the same manufacturer (Rinnai gas heater), the gas fixed flued heater are 44% to 57% more expensive than the portable gas heaters.
Depending on the model and installation situation, you may also need to purchase an accessory flue kit when you install gas fixed flued heater.
Installation Cost of Portable Gas Heaters vs Flued Gas Heaters for the Home
If you already have a gas heater bayonet connection in your home, there is no cost to install a portable gas heaters (portable LPG gas heaters). So, while not prohibitively expensive, it does cost more to install flued gas heaters (gas fixed flued heater) for the home than portable gas heaters (unflued gas heaters).
Even if you need to add a gas heater bayonet connection, the installation costs for portable gas heaters (portable LPG gas heaters) would be modest.
Installation of flued gas heaters (flued LPG gas heaters) in your home requires the services of a gas fitter in all circumstances.
There is also the cost of installing the gas fixed flued heater flue kit through the wall or ceiling.
What Size Gas Heater Do I Need?
What to Consider
If you buy too small a heater, it will not be able to adequately heat the intended area.
Selecting a heater that is too large will cost you extra money and oversizing can be unsafe.
A number of things need to be considered when determining your heater sizing:
♦ The volume of the area to be heated including consideration of ceiling height.
♦ The climate zone that you live in.
♦ The physical features of your home including wall & ceiling insulation, window coverings and carpeting.
♦ The kW output of the gas heater, not to be confused with the gas Mj input.
Heating Area Volume & Climate Zone
The required kW output required is primarily dependent upon the area to be heater and the climate zone in which you live.
The following rough guide assumes your ceilings are no higher than 2.4M:
Very Cold Zone: 1kW output required for each 8.5m²
Cold Zone: 1 kW output required for each 10m²
Cool Zone: 1kW output required for each 13 m²
Mild Zone: 1kW output required for each 16m²
Adjustment Factors
The indicated heating areas would be adjusted down by 5% for each of the following conditions: house built on pillars (non-slab), no carpets on floors, no drapes on windows or a ceiling height exceeding 2.4m.
Deduct an additional 10% if the area does not have ceiling insulation.
Please note that this is only a guide and individual home designs and situations may vary.
Gas Heater Sizing Example #1:
You live in the Cold Zone and you want to heat an area 5m X 10m, which equals 50m².
Because 1kW will heat 10m², you should need a heater with a 5kW output.
Gas Heater Sizing Example #2:
Same as the previous example but in this case your ceilings are over 2.4m and you have wood flooring instead of carpeting.
You would need to deduct 5% for each of these two items.
So, instead of 1 kW heating 10m², it would heat 9m² (10% total reduction).
This means you would need a heater with 5.6 kW of output (50 ÷ 9).
Use kW not MJ
Megajoules per Hour (MJ/hr) ratings on appliances actually indicate the gas consumption of the appliance, not the heat output.
It is often expressed as just MJ.
Kilowatt (kW) is how gas heater output is measured.
Energy Efficiency Matters – Star Ratings
So, remember to use kW as a comparison and not MJ.
The efficiency of the heater, in converting gas energy to heat, is a key factor.
For example, a 25MJ heater with a 5.8 Star rating has an output of 6.2kW.
A 25MJ heater with a 2.8 Star rating only has an output of 5.0kW.
As a result, in a Cold Zone climate, they would heat 62m² and 50m², respectively.
This means that the 5.8 Star heater will heat an area 24% larger while using the same amount of gas.
Please refer to the manufacturers’ specifications to determine the exact kW output for each heater you are considering.
Minimum Room Sizing
Some States specifiy the minimum room sizing (volume of room in M³) and minimum ventilation requirements for unflued heaters.
Minimum room sizing also varies between thermostatically controlled and manually controlled heaters.
Portable heaters should not be used in bedrooms, bathrooms or hallways.
All installations must comply with Australian Standard AS5601 – Gas Installations.
Your gas fitter will be able to guide you on many of these points.
Manufacturer Sizing Charts
To make it even easier, most manufacturers have sizing charts, for their heaters, based on climate zone maps.
Take the time to measure the area you wish to heat and use these charts and maps to get the correctly sized heater.
It is always wise to follow the manufacturers’ advice.