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Gas hot water systems
Gas hot water systems burn either natural gas (also called mains gas or reticulated gas) delivered via a piped network, or LPG (liquefied petroleum gas), which is usually bottled. They can be a good solution depending on your circumstances—for example, if you live in an area with limited sunlight for a solar hot water system or if a heat pump hot water system is not suitable.
Gas hot water systems generally produce far less greenhouse gases than electric water heaters—around 25 to 33 per cent less. They generally also have lower upfront costs than solar or heat pump hot water systems. However, if you don't have natural gas connected to your home you will need to get a mains gas connection or use bottled gas (LPG). Depending on how much hot water you use, LPG may be more expensive to run than natural gas.
There are two main types of hot water systems:
- Storage water heaters heat and store water in an insulated tank for use when it is needed.
- Instantaneous systems (or continuous flow systems) only heat water when it's needed and don't use a storage tank. Be aware that if this leads you to use more hot water, your energy costs may increase
Storage heaters use a gas burner located under the storage tank to heat the water. They usually have a pilot flame that burns continuously and lights the main burner when it's needed. Storage systems lose heat through the walls of the tank so they need to burn gas regularly to keep the water at the desired temperature. These losses can be a significant proportion of your hot water energy use. Well-insulated tanks will have lower storage losses.
Systems installed indoors need a flue that leads outside to vent exhaust gas.
In an instantaneous system (or continuous flow system) there is no storage tank and the water is heated as required. They don't have heat losses from a tank
The water is heated by a gas burner as it flows through a coiled pipe called a heat exchanger. The gas burner starts when a hot water tap is turned on. It only heats the amount of water that is required instead of continuously heating a full tank.
Whether a gas water heater is the best choice for you depends on your particular circumstances.
If you have access to both natural gas and sunshine, you could consider a gas-boosted solar system to reduce your energy use and greenhouse gas emissions. Gas water heaters generate far fewer greenhouse gas emissions than electric storage systems. See our information about installing a gas hot water system.
All gas hot water systems except gas-boosted solar systems have an energy star label to tell you how efficient they are. See energy rating labels to find out about this industry-led scheme. The less gas used the lower the operating costs. This also means reduced greenhouse gas emissions.
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An average household can use around a quarter of its total energy on heating water
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