Hot Water Systems

Did you know that your hot water system accounts for around 25% of your electricity bill? To avoid wasting money on an expensive and unnecessary hot water system, before installing you first need to decide what type of system best suits your needs.

You will need to establish whether an instantaneous or storage system is best suited to your home or investment property, and then consider your options. An instantaneous system heats water only as required, while a storage system stores the heated water in an insulated tank for use on demand.

Electric storage water heaters

Electric storage hot water systems are the cheapest to buy and the most expensive to run if you are using grid-supplied electricity. As the name suggests, they are an insulated tank which is kept full of hot water at all times, ready for immediate use.

They are the most common type of hot water system used in Australian households, the familiar cylindrical shaped drum often found in or near the laundry. In this type of system, the water temperature is maintained at a pre-determined level, usually 60-70°C. Electric heating elements are used to heat the water in a similar way to an electric kettle.

Despite being insulated, once heated, the water temperature will fall because of heat losses from the tank and also from hot water usage. When hot water is used, it is refilled with cold water, which also reduces the temperature. This results in the heating element switching on and using electricity to heat the water again.

Instantaneous electric water heaters

A less common type of conventional water heater is the instantaneous variety, otherwise known as continuous flow. These heaters do not store any hot water, instead heating water on demand whenever a tap is turned on.

This type of system is more efficient, since you only pay for energy to heat water as you are actually using it with none of the losses associated with storage tanks, which keep the water hot regardless of whether it is being used or not.

The downsides are that they are more expensive to buy and require much higher power inputs, depending on the size of the system, three-phase power may be needed.

One non-conventional type of electric hot water system uses a heat pump to retrieve energy from the air to heat the water, rather than converting electricity into heat energy. Heat pumps work on the same principle as a reverse cycle air conditioner and in this type of system, they are used to heat water instead of air.

This type of system is expensive to buy and install, but very efficient, using only 30% of the power needed to run a conventional water heater. Not all models are suitable for colder climates, especially where the temperature regularly falls below 5 degrees.

Gas storage systems

Similar to electric storage systems, gas hot water systems have a tank of water that is kept heated, ready for use at all times. Instead of an electric element, this type of unit heats the water with a gas burner underneath the storage tank. There is usually a pilot flame which burns constantly to ignite the main gas burner when it is required. The system has a flue and some of that heat can also be diverted to heat the water, increasing efficiency. These units come in sizes between 90 litres and 300 litres

Instantaneous gas hot water systems

Also called continuous flow, this type of heater doesn’t have a storage tank, instead it only heats water when required in the same manner as the instantaneous electric system. A gas burner heats the water flowing through an element consisting of a coiled pipe known as a heat exchanger. When water starts to flow through the system due to a tap being turned on, only the amount of water required is heated instead of a tank of water being kept hot. This means there is no heat loss from a tank which translates to cost and energy savings.

To allow time to heat the water, it is slowed down while flowing through the heat exchanger. This means the output of this type of system is at a lower pressure than the storage type of systems.  The rate of flow per minute (depending on the model) will be between 10 litres and 30 litres.

The estimated lifespan of a hot water system is 8 to 10 years. The worst case scenario you can create for yourself is to wait until after the hot water system fails to replace it. A hot water system is more likely to fail at the worst possible time, when the highest load is being put on it, frequently on days that are colder than usual.

There are warning signs that your system is about to fail, such as the hot water running out quickly, water temperature fluctuating, unusual noises such as rumbling coming from the system, rusty or discoloured water coming from the hot tap, water leaking from somewhere on or around the system. On a gas system, warning signs include the smell of gas and the pilot light being yellow instead of blue.

www.energy.gov.au/households/hot-water-systems

If you are looking to install a new system or remove and replace an old system, we can assess your needs and offer a wide range of options to choose from.