Central heating systems compared
The central heating comparison table assumes well designed and efficiently operated systems and gives general running costs and greenhouse gas emissions. Obtain expert advice before making decisions on the type best for you.
|System type||Running cost||Greenhouse gas emissions|
|High efficiency ducted natural gas||Low||Low|
|Hydronic zoned natural gas or heat pump||Low||Low|
|Ducted reverse cycle or heat pump||Medium||Medium (low with green/renewable electricity source)|
|Hydronic zoned with wood/solar heat source||Low||Very low (if from a renewable resource and seasoned wood)|
|In-slab high off-peak electric||Medium–high||Very high (low with green/renewable electricity source)|
These devices heat a smaller area — one or perhaps two rooms — and come in a wide range of types.
Electric portable heaters
Electric portable heaters can be cheap to buy but are expensive to run and sometimes ineffective.
- Radiant heaters, such as bar heaters, are good for bathrooms as they give almost instant heat direct to your body and do not directly heat air. Less warm air is lost than with other heater types and they heat your body even when an exhaust fan is used. No thermostat is fitted so use a timer or switch. Turn off radiant heaters when leaving the room for any length of time.
- Fan heaters heat the air and provide convective heat. Larger upright models are more effective. They can warm smaller rooms quickly and some have thermostats to help reduce energy use.
- Convector heaters heat the air, which then rises naturally. They are not recommended for rooms with high ceilings or poor insulation levels or where there is a high ventilation rate.
- Combined convector/radiant heaters are larger than fan convector units (but may have a small fan to increase heat output). They have a large surface that becomes hot and radiates heat, as well as slots to allow heated air to rise into the room.
- Oil-filled column heaters supply a mix of convective and radiant heat but are slow to respond. Some have thermostats, timers and fans.
Heaters that don’t rely on fans and do not reach high temperatures are more suited to bedrooms, as they are less likely to overheat and cause fires if clothes are accidentally placed on them. All electric heaters should have a safety cut-out to avoid overheating.
Electric systems may produce high greenhouse gas emissions — up to six times as much as an efficient gas heater. However, using a small electric heater for local heating may be cheaper and have lower emissions than heating a much larger area with gas. Offset electricity greenhouse emissions by using 100% GreenPower.
Offset electricity greenhouse emissions by using 100% GreenPower.
Electric fixed heaters
Reverse cycle air conditioning (or heat pumps) provides convective heat and is the most energy efficient electric heater. The most efficient 5–6 star units may be cheaper to run and generate lower greenhouse gas emissions than gas heaters. Visit the Energy Rating website (www.energyrating.gov.au) to find the most efficient reverse cycle air conditioners.
Wall panel convectors use peak electricity and are expensive to run, like portable electric heaters.
Off-peak electric storage heaters provide a mix of radiant and convective heat. They use bricks to store heat produced overnight using off-peak electricity. Unless carefully controlled they can lead to overheating in milder weather, and they continuously ‘leak’ heat, so their overall efficiency in intermittently used spaces is low.
Gas portable heaters
Unflued portable heaters can provide either convective or radiant heat and run on natural gas or LPG.
Adequate ventilation is needed to maintain good air quality, which can significantly reduce efficiency. An efficient externally flued heater is usually preferable but may not always be an option, particularly for tenants. In these cases units are available that burn more cleanly, producing lower combustion emissions and requiring less ventilation.
Unflued gas heaters often create condensation problems — usually at the opposite (coolest) end of the house. Take care to ensure they don’t lead to mould growth.
The use of unflued heaters is restricted in some states because of their associated indoor air pollution hazard, which can cause health problems. Check your state or territory regulations for details.