Gas Hot Water Tanks from Rheem, Everhot, Aquamax, Thermann

Gas hot water tanks aka gas storage hot water heaters are the second cheapest heater to install next to electric. They are fairly basic in design with only a few components.

  • Vitreous enamel coated steel tank – higher end tanks available in Stainless Steel
  • A replaceable sacrificial anode inside the tank roughly the size and shape of a broom handle. These erode over time but prevent corrosion of the tank. These can be changed around the 5 year mark to considerable extend the life of the tank, though few people are aware of this.
  • A gas burner under the tank
  • Constant gas pilot light to ignite the gas burner
  • A thermostat that measures the water temperature and determines when to turn on the gas burner.

Manufactures seem to have become quite good at building storage tank heaters both electric and gas, to last just past the warranty period. Perhaps something to do with the size of the sacrificial anode used. Tank are available with different warranties, usually its 5 or 7 years however some of the higher end stainless steel models come with 10 year warranties.

Running Costs

Although the initial installations cost of a gas hot water tank makes them the a cost effective choice, they are the most economical heater to run in the long term however that are still far cheaper to run than the electric alternative.

Rheem running cost calculator

And from it some examples:

Electric hot water tank – Domestic Tariff – $1526.29 a year in electricity

Electric hot water tank – Off Peak Tariff – $665.45 a year in electricity – not too bad but needs a meter upgrade and only heats water between 11pm and 7am so if you use it all up during the day you have no hot water at night unless you get a dual element heater and have a booster. But then you’re back to square one paying full domestic tariff to heat the water during the day.

Gas hot water tank – $549.44 a year in Natural Gas – no time restrictions like off peak electric but still requires time to recover from heavy hot water usage.

Continuous flow gas hot water 5 Star – $469.98 per year in Natural Gas

Continuous flow gas hot water 7 Star – $410.98 per year in Natural Gas

Tempering Valves

Since 2013 all hot water supplied to sanitary fixtures (basically anything except the kitchen sink or laundry tub) must be tempered to a maximum of 50 Celsius. For more information on when and why these are required and how much they cost click the link below

Tempering Valves

How much to supply and install?

Below is a rough guide to cost of a straight swap, like for like, heater replacement including removal of the old heater but not including a tempering valve. Most manufactures supply tanks with a 1 year parts and labour warranty and a 5, 7 or 10 year warranty on the tank.

All prices include GST

90 Litre – $1195

130 Litre – $1245

170 Litre – $1365


Prices may vary around 5% either way depending on brand and model. Above is just a guide only.

Pros and Cons


  • Second cheapest supply and installation cost.
  • When replacing like with like there is no need to consider current plumbing as it should go straight in
  • Second only to electric in terms of ease of installation
  • Around 25% more to run gas wise than a continuous flow heater which is still pretty cheap
  • Faster recovery rate than electric, therefore a smaller size tank requirement than electric


  • Large bulky footprint and not the most aesthetically pleasing sight down the side of a house
  • As hot water is used cold water enters the tank to replace it. The more hot water used the lower the temperature in the tank as the gas burner can’t always keep up with the demand.
  • The first part to fail is usually the tank itself at around the 8 to 12 year mark and it is not repairable. Only option is to replace it
  • Water wastage through worn temperature relieve valves is common especially in Summer

Don’t Miss Out!

If you switch from an electric storage hot water system to a continuous flow hot water heater before March 31st 2015 you may be eligible for a $500 eftpos card to use at any eftpos terminal across Australia courtesy of Jemena, the natural gas network supplier.

Call Rupes Today – 0414 555 674