CONTINUOUS FLOW/ INSTANTANEOUS GAS HOT WATER HEATERS

 

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

 

Instantaneous gas hot water systems, also known as continuous flow, don’t have storage tanks and heat water only when required.

 

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. As they don’t store any hot water, there is no heat loss from a tank and so can have energy and cost savings.

 

To allow enough time for heating, the water is slowed down as it flows through the heat exchanger. This means that instantaneous units supply hot water at a lower pressure than storage systems. They can typically deliver hot water at flow rates per minute of between 10 litres and 30 litres, depending on the model.

 

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