Replacing your hot water system is both inconvenient and expensive, so it pays to carefully consider a hot water storage tank that will stand the test of time as well as deliver energy (and cost) efficiencies.
Storage tanks for hot water systems are made from either stainless steel or from carbon steel with a coating of vitreous enamel.
Stainless steel hot water storage tanks
Stainless steel tanks are made from 316 stainless steel, a material which is typically used in the marine industry because of its high corrosion resistance. The 316 stainless steel provides a natural barrier to corrosion that is virtually maintenance free.
This characteristic of stainless steel is evident by the use of 316 or its sister alloy 304 in many other areas of the home including kitchen sinks, dishwashers, washing machines, pots, pans, cutlery and fridges.
The material's strength and inherent corrosion resistance as well as its fatigue resistance from the stresses of constant temperature and pressure variation during service makes stainless steel a strong and durable option.
Vitreous enamel hot water storage tanks
Because carbon steels will corrode in contact with air or water, the surface of the tank must be protected by a layer of vitreous enamel added to line the interior of carbon steel.
However, manufacturers can't make the enamel layer perfectly impervious. The steel and enamel lining expand and contract at different rates as the temperature in the tank rises and falls. This can cause the enamel to craze or come unstuck from the steel, exposing it to water and corrosion. This is a particular problem if the water temperature is set too high.
The steel exposed at the coating defects is protected by the use of a 'sacrificial anode' that acts to prolong the life of the tank. These anodes, usually made from a magnesium alloy, require checking at regular intervals and replacement every 5-7 years on average.
Some water qualities (such as very soft or very pure water) are inappropriate for this system because characteristics of the water render the anode ineffective.
Stainless steel storage tank manufacturers
Edwards Hot Water, Aquamax and Beasley Water Systems are some of the main stainless steel storage tank manufacturers in Australia.
ASSDA member, Edwards Hot Water, has over 35 years of experience in the manufacture, supply and installation of stainless steel hot water systems. Edwards Hot Water exports tanks to 40 countries and the tanks comply with AS2712, the benchmark standard for hot water systems.
Manufacturers of stainless steel hot water tanks give long warranties because in the majority of conditions the tanks perform excellently and provide years of trouble free service without the need for regular maintenance or consumable parts.
Choosing a stainless steel hot water system means long life, low maintenance and a long warranty.
Image courtesy of Edwards Hot Water.
This article featured in Australian Stainless magazine - Issue 30, January 2005.