A gas heater is a great solution for heating a large space quickly and cost-effectively. We explain the difference between flued and portable heaters and give some tips on what to look out for.
How much space are you heating? The measurement of a gas heater's warming capacity isn't just about room size, it's also about how quickly the heater can warm the space.
The room size and local climate will determine what size gas heater will effectively heat your room.
Portable or unflued gas heaters must not be installed in a room too small for their rated capacity due to the emissions they produce. For fast heating, choose the biggest capacity (measured in MJ/h) suitable for the room size. A lower capacity heater can still heat the room but will be slower.
Once you've decided you need a gas heater you'll need to consider the size. Overspending on a larger gas heater than necessary means wasted money upfront and higher ongoing running costs. Under-spending means you aren't able to heat your room properly.
Use the kWh heat output in our gas heater review to decide roughly what size heater you need. 1 kWh roughly heats 10 square metres.
There are heaps of caveats and variables to this. The climate zone you live in, your ceiling height, whether rooms next to the one you're heating are heated, whether you've got insulation, whether the room gets direct sunlight, how big the windows are and whether they have solid curtains or are double glazed.
Gas heater room size guide
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A flue is a pipe that carries exhaust gases from your heater or fireplace to the outdoors, saving your room from being filled with fumes. They're pretty important. If you're renting, or don't want to go to all the fuss of a flue, you might want to look at a portable or unflued gas heater. There are benefits and drawbacks to both flued and portable heaters.
Pros of a portable gas heater
- Easier to move – you can point them in different directions, move them from room to room, store them away in summer and take them with you when you move house.
- Very efficient compared to a portable electric heater – about 90% of the energy content of the gas is transformed into heat. All models sold in Australia have to be certified and carry an efficiency label (up to six stars, with six being the best).
- Provide instant heat – and lots of it. Unflued gas heaters come with a capacity of up to 25 MJ/h (megajoules per hour). That's equivalent to more than 6kW of electric heating – the same as you'd get from three 2kW electric heaters.
- Much cheaper to run than portable electric heaters, even though they're a lot more expensive to buy.
- Produce a quarter to a third of the carbon of an equivalent electric heater (unless you get your electricity from renewable sources).
- Range of safety features (in modern models) that switch the heater off in case something's wrong. For example, an oxygen depletion sensor if the oxygen level in the room gets too low, flame failure protection in case the flame gets extinguished, and a tilt switch in case the heater tips over. But make sure that you install a carbon monoxide alarm as well, just in case.
Cons of a portable gas heater
- No flue means emissions from the gas combustion process in the heater are vented back into your room.
- Illegal to use in bedrooms, bathrooms and other small or badly ventilated rooms, so for those areas you need a flued heater (which vents the products of combustion via a flue to the outside), or an electric heater.
- Further restrictions on using this heater type apply in some states. Check with a gas plumber or retailer. Victoria no longer allows gas bayonets to be installed for the purpose of an unflued gas heater.
- Produces carbon monoxide (CO) and nitrous oxides (NOx), but only in relatively small quantities – Australian emission standards are among the toughest in the world. However, they can still lead to or exacerbate asthma and other respiratory problems, especially in children. See Health concerns below.
- Water vapour from the combustion process can condense on walls and ceilings and cause mould, which is why ventilation is so important.
- Remote controls allow you to control the temperature settings and fan speeds, with some models offering both wired and wireless versions so they can extend a further distance.
- Thermostats make it easier to set a desired temperature.
- Programmable timers will help with energy saving. Most can be programmed to turn on and off during a 24-hour period.
- Child locks are available on some models, and are a very important safety concern for us here at CHOICE. We would like to see this feature on more products in future.
- Electronic ignition is great, because it means potential energy savings due to not having to have a pilot light running at all times.
- A filter-clean warning feature is very useful, so you can be sure to clean it regularly and as needed.
- An LPG conversion kit allows you to operate the heater in areas without natural gas, but be careful – operating costs will be higher as a result.
Gas heaters have been identified in several studies as a factor contributing to childhood asthma and other respiratory health problems. Gas flames release small but measurable amounts of contaminants such as nitrous dioxide and fine particulate matter.
Gas heaters are required to meet strict emission standards to minimise the amount of such contaminants they produce, but some trace amounts still escape, and a faulty heater can produce a lot more (that's why you should keep your heater serviced).
Studies have found that unflued gas heaters are associated with a higher prevalence of asthma in children, as well as increased symptoms for children who already had asthma, and a greater risk of acute respiratory infections.
Flued gas heaters and central ducted gas heating may be less likely to have this risk, but even they can release some emissions into the indoor air, so the risk is not zero for these types either.
Installation will cost you on top of the heater itself. Buying last year's model and asking for a discount might help, so you can put the savings towards the installation.
CHOICE strongly recommends professional installation for these heaters, as many things can go wrong. In our tests of gas heaters over the years, we've found cases where the wrong parts were supplied, manuals incorrectly printed, and even found that some heaters were incorrectly assembled to the point of being potentially dangerous.
If you have a gas heater of any type (whether flued, portable unflued, or ducted central heating) then make sure to install a carbon monoxide alarm too – they're readily available from hardware stores. This could save your life if the heater develops a fault and starts putting out dangerous amounts of this deadly gas.
Not necessarily. Most units can be installed into an existing fireplace, with an existing chimney accommodating the flue; otherwise you can use a firebox and put the unit anywhere in the room, as long as you can incorporate a flue.
The average price range for flued heaters is from $1200–2200.
There are two different types of portable or unflued gas heaters.
These rely on the natural movement of hot air, but also have a fan to speed things up. They're often electronically controlled, which means they have, for example, a thermostat and a remote control. A thermostat is particularly useful, as it provides better temperature control than the heat and fan settings on models that aren't electronically controlled. However, electronically controlled models also use standby power – some more than 10W. The external surfaces on convectors shouldn't get very hot.
These also rely on convection, but have an exposed area that radiates heat into the room. Radiant convectors tend to be cheaper to buy, but have fewer features (no thermostat, timer, remote control, etc) than similarly sized convection heaters. They have manually operated electronic ignition (you need to press the ignition button and hold it down for about 20 seconds).
The average price range for portable heaters is from $400–1400.