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SILICON
SILIC
CHIP
www.siliconchip.com.au
Publisher & Editor-in-Chief
Leo Simpson, B.Bus., FAICD
Production Manager
Greg Swain, B.Sc. (Hons.)
Technical Editor
John Clarke, B.E.(Elec.)
Technical Staff
Ross Tester
Jim Rowe, B.A., B.Sc
Nicholas Vinen
Photography
Ross Tester
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Phone (02) 9939 3295
Mobile 0431 792 293
glyn<at>siliconchip.com.au
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Brendan Akhurst
Rodney Champness, VK3UG
Kevin Poulter
Stan Swan
Dave Thompson
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4 Silicon Chip
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
siliconchip.com.au
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November 2012 5
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