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  • Last Updated: 09 December 2021

Gas Heater Efficiency Comparison – Energy Star Ratings – Gas Energy Rating: Gas Heaters & Fireplaces

The gas energy rating of gas appliances is signified using a star rating scheme. However, the energy efficiency can be affected installation location, usage, climate, ambient air and water temperature, humidity, number of sunny days, insulation, windows and other factors.

It basically compares gas heater efficiency or wall furnace efficiency by the amount of raw energy input consumed by the gas heater in comparison to the heat energy output provided.

When doing a gas heater efficiency comparison, Star Ratings for unflued gas heaters are from 5.8 to 5.9 Stars, meaning that they have about 90% gas heater efficiency. Flued heater have 1.0 to 4.8 Stars and 61% to 84% gas heater efficiency. So, you could save as much as 32% of the cost of heating by choosing unflued gas heaters compared with some flued gas heaters.

For a gas heater efficiency (gas energy rating) comparison, including gas fireplace and wall furnace efficiency, we rely on Star Ratings.  Initially the energy efficiency labeling scheme for gas heaters, both flued and portable gas heaters, was started as an industry gas energy rating program, run by the Australia Gas Association (AGA).
Star ratings provide a relative gas heater efficiency comparison based on tested and labeling, a gas energy rating which is required for all gas heating units, including wall furnace efficiency. Understanding Star Ratings, and the gas heater efficiency comparison behind them, can save you lots of money…

Gas Energy Rating

Certain appliances can have their gas energy efficiency rating and performance affected by the installation location climate zone, ambient temperature, set temperature, home insulation, incoming water temperature, set temperature, and other variables.

Gas Wall Heater Efficiency

Gas wall heater efficiency is the same as other flued gas heaters. It basically compares gas wall heater efficiency by the amount of raw energy input consumed by the gas wall heater in comparison to the heat energy output provided.

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).

What do the ratings mean?

Star ratings (gas energy rating) were developed to provide consumers with an easy way of comparing the energy efficiency of different gas heater models.

It has now become part of the certification requirements.

All States now require both LPG and Natural Gas heaters for sale to be tested and certified, under AS4553.

Testing is done by independent testing organisations, such as the AGA and SAI Global.

Net Heater Efficiency – Gas Energy Rating

The Star Rating is based on net heater efficiency gas energy rating.

Net heater efficiency is calculated on the basis of a combination of efficiency measures and takes into account all gas and electrical inputs.

It basically compares gas heater efficiency or wall furnace efficiency by the amount of raw energy input consumed by the gas heater in comparison to the heat energy output provided.
This gas energy rating is calculated as a percentage and then translated into the corresponding Star Rating.
Please visit www.energyrating.gov.au for more information.

Please see How To Install a Gas Heater
Gas Space Heater Star Ratings and Thermal Efficiency Values
Star Rating 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Thermal Efficiency

How do you use this information?

Example 1

Say, for instance, you have an old gas heater that is only 1 Star Rated and you spend about $400 per year on gas to run it.

If, for example, you upgrade to a 5.8 Star Rinnai Avenger gas heater, you would save roughly 30% on your energy costs, or $120 per year.

As it is not unusual for a gas heater to last 20 years, this means you could save $2400 over the lifetime of the heater, less the initial cost of the new gas heater.


Example 2

In a different example, using the same $400 hypothetical gas budget, if you had the choice between purchasing a 2.5 Star model and a 3.5 Star model, the savings would be 6% or $480 greater with the 3.5 Star model over 20 years.

However, if the 3.5 Star model were to cost you $600 more to buy, than the 2.5 Star model, the savings would never equal the added purchase cost.

Having this information could affect your choice of heaters.


Combination of Purchase Price & Operating Cost

Remember that you need to consider both the purchase price and the cost to operate the heater when making a decision.

Please also remember that the more efficient the heater, the smaller your carbon footprint.

Compare Indoor Gas Heater Prices

Now you can compare prices for all the major brands of indoor gas heaters including:
Rinnai gas heater, Everdure, Paloma gas heater, Braemar and Cannon
Click on your category of interest to compare prices:

Portable Gas Heater Prices

Flued Gas Heater Prices
Gas Fireplace and Gas Log Fire Heater Prices



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The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.