Gas hot water cylinders

Gas hot water cylinders are less efficient than gas continuous flow systems, but do work during power cuts.


  • There's no electricity required, so gas hot water cylinders continue to heat and supply hot water during power cuts.
  • Condensing gas hot water cylinders are more efficient than conventional gas hot water cylinders.
  • Can be located outside your house, which can free up space inside.

Keep in mind

  • The running costs are relatively expensive.
  • You will have to pay a fixed charge for reticulated gas supply (if you don't already).
  • While burning gas is relatively clean, the greenhouse gas emissions contribute to climate change.
  • For safety reasons you can't put a cylinder wrap around a gas hot water cylinder (this could obstruct the air flow and extinguish the flame).
  • The system needs to be correctly set up to ensure the water in the tank is regularly heated to 60oC to prevent the growth of legionella bacteria.
  • Use our water heating tool to compare the upfront and ongoing costs of different water heating options for your situation.

?Water heating tool

How they work

Gas hot water cylinders burn gas to heat the water in an insulated tank to a temperature set by a thermostat. They typically run on natural gas.