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Publisher's Letter

Replacing sacrificial anodes in hot-water systems is good for the environment

This month, we have a seemingly low-tech story about replacing the sacrificial anode in a mains-pressure off-peak hot-water storage tank. Why would we have such a story in SILICON CHIP? Well, why not? SILICON CHIP readers are concerned about energy efficiency and as a corollary of that, in getting the best performance from anything electrical or electronic. And hot-water systems certainly fit into those criteria.

There are millions of these tanks in homes and businesses throughout Australia and yet most owners and users of these tanks are blithely unaware that there is such a “thing” as a sacrificial anode in their tank and that it should be inspected and replaced on a regular basis. Of course, this does not only apply to mains powered hot-water systems. It also applies to gas fired systems, solar hot-water systems and even those that use a heat pump as the power source; anything with a steel storage tank and with mains water pressure is at risk of corrosion and eventual failure.

And yet I know that if you ask all your acquaintances about the state of the sacrificial anode in their hot-water systems you will get a blank stare from virtually all of them. Boat owners know about sacrificial anodes but virtually no-one else does, including the people who install them: plumbers.

Boat owners do have their sacrificial anodes replaced regularly, usually every year, but those same owners probably don’t know about the one in their hot-water system.

What this means is that virtually all the millions of hot-water systems in use throughout Australia give far less than their potential life span. And since most mains-pressure hot-water systems typically last less than 10 years, precisely because their sacrificial anodes were not replaced when they should have been, that probably means that the annual cost in Australia runs into 100s of millions of dollars a year.

It get worse though, if you consider the cost of replacing solar or heat-pump systems. These generally cost far more to install than the lowly and these days much-despised off-peak electric hot-water systems yet as far as I know, owners of these systems are seldom specifically told about the need to inspect and replace sacrificial anodes.

Solar hot-water systems are even more at risk because they typically have a roof-mounted horizontal tank, unless you are fortunate enough to have purchased a stainless steel tank which does not need a sacrificial anode! Roof-mounted tanks may not be out of sight but their corrosion risk is certainly out of mind.

So while many people may worry about the cost of electricity and more specifically, the cost of hot water, they are completely unaware of the possible liability for the large one-off cost of replacing the entire hot-water system. Think about the cost of the tank and its installation.

Personally, I want to keep my off-peak hot-water storage system going for as long as possible because there is no guarantee I will be able to replace it with a similar unit when it eventually fails. Ultimately, I will probably replace it with a solar system but I would prefer to postpone that as far into the future as possible.

I also like to think that I am being “environmentally friendly” with such an approach. Sure, I am potentially saving money but then I am also saving the resources which would otherwise be required to replace the tank.

So here is our strong suggestion. Get your hot-water system’s sacrificial anode inspected.

Leo Simpson

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