A gas heater can be a very effective solution for heating a large space quickly and cost-effectively. However there are a few points to think about with gas heating, including choosing the best type, sizing the heater correctly for the room, and safety aspects of gas appliances. We explain the difference between flued and portable heaters and give some tips on what to look out for.
When you're weighing up how to heat your home, whether a single room or the whole house, there are many options. For example, if you have your own solar panels, electric heating (such as reverse-cycle air conditioning or other types) is probably much more cost-effective than gas heating. Check our home heating guide.
Gas heating can be an effective option and when the price of gas is right, a fairly cost-effective option too. On the down side, gas heating has potential health risks connected to it; see Health concerns, below. There are safety considerations too, though these can be managed by correct installation and maintenance of the heater. Gas is also a non-renewable resource with potentially uncertain long term pricing.
Portable or unflued gas heaters must not be installed in a room too small for their rated capacity due to the emissions they produce. A gas heater's capacity is a measure of the amount of heat energy it can put out, in megajoules per hour (MJ/h). For fast heating, choose the biggest capacity suitable for the room size. A lower capacity heater can still heat the room but will be slower.
Once you've weighed up these factors and decided a gas heater is the way to go, look at the types and sizes available.
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.
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.
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 many 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.
A point to consider is that gas is a non-renewable resource and the long term price of the fuel is uncertain. While gas is still a reasonably cost-effective way to heat a room compared to portable electric heaters right now, gas prices have fluctuated in recent years due to several factors. It's likely that the long term price trend is upwards. One of the advantages of electricity over gas is that you can generate your own cheap electricity with solar panels, which can make electric heating (especially reverse cycle air conditioning) a much cheaper option in the long run.
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 unflued (portable) gas heater. There are benefits and drawbacks to both flued and unflued heaters.
Unflued (portable) gas heaters
- 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. (They are portable in the sense that you can pick them up and move them, but they still need a gas bayonet to connect to, so they can't be installed just anywhere.)
- 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.
- Cheaper to run than portable electric heaters (unless the electric heater is running on your own solar power), 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.
- 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, or reverse-cycle air conditioning.
- 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 (unless the heater is faulty or poorly maintained) – 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.
- Regular maintenance every couple of years or so is required to avoid problems with the emissions mentioned above.
- Water vapour from the combustion process can condense on walls and ceilings and cause mould, which is why ventilation is so important.
- Gas has to be bought from a gas supplier, while with electricity you have the option of generating it at home with solar panels. Gas is a non-renewable resource, which is an increasingly important consideration for many people.
Flued gas heaters
- Most of the same points about heating effectiveness and efficiency above also apply to flued gas heaters.
- Can be installed in a smaller room where an unflued heater is not permitted.
- Minimal risk of harmful emissions and water vapour escaping into the room (they exit via the flue).
- Can be an attractive "fireplace" feature in the room.
- Usually more expensive to buy and install than an unflued/portable gas heater.
- Some heat is lost through the flue (chimney) so this type is a bit less energy efficient than an equivalent unflued gas heater.
- While the risk of harmful emissions escaping into the room is lower than for an unflued gas heater, it can still happen if the heater is faulty or poorly maintained. Regular maintenance is still important for flued gas heaters.
- 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 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. We would like to see this feature on more heating appliances.
- 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.
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).
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.
Do you need a chimney for a flued gas heater?
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 to the outside of the home.
A gas heater is built for either natural gas or liquified petroleum gas (LPG). Natural gas is run directly to your house by gas companies, and LPG is supplied in tanks.
Gas heaters are built for the different types of gas supplied, so make sure you know which one you need prior to ordering one. LPG for bottled gas, and Natural gas for gas that is piped to your home.
There are pros and cons to both, but ultimately if you don't have natural gas piped to your home you can only use LPG (this is usually the case for regional customers).
The average price range for portable heaters is from $400 to $1400.
The average price range for flued heaters is from $1200 to $2200.
Stock images: Getty, unless otherwise stated.