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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 Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Brendan Akhurst Rodney Champness, VK3UG Kevin Poulter Stan Swan Dave Thompson SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 003 205 490. ABN 49 003 205 490. All material is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Hannanprint, Noble Park, Victoria. Distribution: Network Distribution Company. Subscription rates: $97.50 per year in Australia. For overseas rates, see the order form in this issue. Editorial office: Unit 1, 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. Fax (02) 9939 2648. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 Recommended and maximum price only. 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 PCB PANEL SHARE SERVICE NO TOOLING COSTS NO MINIMUM PCB SIZE NO MINIMUM ORDER QTY FULLY TESTED QUALITY MANUFACTURE Specifications for the PCB 1.6mm FR4 2 or 4 Layer 1oz Copper Green Solder Mask White Component Reference Silver Finish (RoHS) No PAD or HOLE restrictions Internal & External Routing Maximum 8 hole sizes 0.15mm Track & Gap No V-score All holes are plated through Only one design per order Minimum order value $25 5 Days delivery ex factory get quotes and order online WWW.PCBZONE.NET siliconchip.com.au November 2012  5