GAS STORAGE HOT WATER

 

Gas water heaters make up approximately 48 per cent of water heaters in Australia and are commonly found in New Zealand. The term “gas water heaters” covers three main product types, gas storage water heaters (GSWH), instantaneous or continuous flow gas water heaters (IGWH) and solar water heaters with instantaneous gas boosting (SWHs).

 

Gas hot water systems use either reticulated/piped natural gas or Liquefied Petroleum Gas (LPG) to heat water.

Gas storage hot water systems

 

Storage gas hot water systems use a gas burner located underneath the storage tank to heat the water.

 

They usually have a continuously burning pilot flame that ignites the main burner when it is needed. Heat is then transferred from the gas burner through the bottom of the cylinder.

 

Some heat also flows from the hot flue pipe into the water. When hot water is drawn off at the top of the tank, cold water enters the tank at the bottom.

 

Most units have an adjustable thermostat to set the water temperature. When the temperature at the bottom of the tank drops below the level set on the thermostat the pilot flame ignites the main burner so the water is kept constantly hot. The energy from the pilot flame is not wasted as it helps to heat the water in the tank.

 

Storage hot water systems come in a range of tank sizes from about 90 litres to 300 litres. Some units use a special flue system to recirculate the hot flue gases around the outside of the tank to increase heat transfer into the water and increase their efficiency.

 

from http://www.energyrating.gov.au/products/water-heaters/gas-water-heaters