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Engage: Solar Water Heater

Cheap hot water … or bacteria factory?


With rising energy costs and concerns about climate change, many people have bought renewable, clean energy systems for their homes. A solar hot-water system uses heat from the sun to produce hot water for use around the home. The main parts of the system are the water storage tank, and a large black panel of pipes called the collector. The collector is placed where it will get the most sun, usually on the roof of the house.

Did you know? – Australia gets more sun than any other country in the world!

In fact, solar hot-water heaters are so effective that the water in the black pipes often boils! This can lead to a loss of water as steam. In areas such as outback Australia where water often has to be delivered in trucks at great expense, it is very important not to waste water.

Water needs to flow from the storage tank into the collector where it is heated, and then flow back into the storage tank. Many commercial solar hot-water systems have a pump to help circulate the water through the system. This can make them quite expensive to install.

To help solve these problems, a company has designed a solar water heater specifically for use in dry, remote areas that is simple to install and provides some protection against evaporation. This system does not require a pump. The water circulates all by itself as you will learn in this FARLabs experiment.

You will also determine if the solar hot-water system could contain Legionella bacteria! Legionella bacteria causes Legionnaires disease which can be deadly to humans.

La Trobe University solar hot water unit
The solar hot-water heater that you will use in this remote experiment.

A test version of this solar water heater has been installed at La Trobe University in Melbourne. In this FAR Lab experiment you will monitor the temperature of the water inside the storage tank over a 24-hour period, and investigate the temperature at different locations within the tank.