House and Garden

3 July 2012
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Hot Water

There are three common methods of heating water in Australian homes; electric (used in 52% of homes), mains gas (36%) and solar (8%)1.

It is estimated that on average, about 25% of household energy use goes into heating water2.

Gas Hot Water

Mains gas is the most common method of heating water in WA, SA and Victoria. It is quite common to have a combined boiler/storage tank located outdoors. They range in size from about 100-300 litres. At first (for those coming from colder climates) it seems strange to have your hot water tank outdoors, but that is the most common scenario here.

However, you could have your gas storage heater located indoors and you can also get instantaneous (constant flow) gas systems, which only heat on demand, that are located indoors. They need to have a flue to take the fumes outside.

Where mains (natural) gas is unavailable, bottled gas (LPG) can be used. However, the systems are different and running costs are 2 to 3 times that of mains gas heaters.

Electric Hot Water

About half the households in Australia use electricity to heat their water. The trend varies from over 90% in Tasmania to 26% in WA.

This method produces more greenhouse gas emmissions than the other main alternatives, so the government has taken measures to phase it out. In most houses, you can no longer fit a new electric hot water system, although of course, you may acquire one when you buy an existing house. Like gas storage heaters, they can be located indoors or outdoors and come in various sizes, from about 50 through to 400 litres.

Solar Hot Water

Although only accounting for 8.5% of the market in 2011, solar hot water is backed by government incentives and is gaining popularity. Normally, the system consists of a number of solar panels plus a tank that sit on your roof (thermosiphon system). Water flows through the panels, rises as it heats and goes into the tank.

A gas or electric booster may be required for areas or seasons when there is insufficient sunlight. Also, in frost-prone areas, a special system is required to avoid the water freezing inside the panels.

Solar hot water systems attract Small-scale Technology Certificates (STCs) which are most often used to offset some of the initial cost. For example, a 300 litre system may attract 25-30 STCs which are currently worth about $25 each, so you would get about $650 off the price. You should also save on your bills, of course, hopefully recouping the cost of the system over its lifetime.

Data Sources

1ABS: 4602.0.55.001 - Environmental Issues: Water use and Conservation, Mar 2011
2Your Home website