Hot Water System sacrificial anodes

The first I ever heard about sacrificial anodes in hot water heater was when The Tap Doctor started trading in Cairns around 15 years ago. They did a flyer drop to introduce their business and offered a free inspection of each new customer’s hot water heater.
The next I found out about the anodes was when our 400 litre dual element Rheem started blowing hot water out through its top onto the soffit at the rear of our house. After we replaced it with a Saxon Heat Pump, I unscrewed the hex head fitting of the sacrificial anode. All that remained of it was the hex head and the thread.
When I was purchasing the Saxon, the staff member at the hardware store told me that he had asked the Rheem rep why their hot water heaters had such a poor service life. He said that she replied that they were in the business of selling hot water systems.
I checked all signage attached to our old Rheem, the owner’s manual and their website and nowhere could I find any mention of sacrificial anodes let alone routinely replacing them to prevent the heater from failing.
Saxon systems did not need an anode as they have copper storage tanks and I have heard from plumbers who have replaced 30 and 40 year old units which were still working only because the owners were having renovations carried out.
What a travesty of natural justice that the manufacturer was forced to close due to increasing costs whilst the rubbish which is designed and built to fail continues to be dumped on the unwary.
So, unless you have a Saxon or a model with a stainless steel storage tank, make sure you have it checked before you find out the hard way. The anodes appear to last around 7 years with good quality water but less time with poor quality water.

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Not true about Saxon water heaters being long lasting maybe in areas of very soft water, I purchased one for a rental property years back on the promise it would last a long time. It was leaking from the vessel in under 7 years and when i replaced it I found cutting it open the copper tank is just sheetmetal thin because they are a simple tank and heat exchanger and it had corroded through in a number of places. A plumber friend says he sees this all the time with saxon units in areas where there is high calcium content of the water.

They are not thick vessels like to old rheem coppermatics that were actually pressure vessels and quite thick they did last forever.

The replacement vitreous enamel steel rheem cylinder lasted nearly 15 years with only one replacement anode around the 9 year point and was still leak tight when decommissioned but was only replaced with a heat pump unit in a rebate deal that effectively cost nothing to upgrade to the heat pump HWS.

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Sacrifical anodes have been in hot water systems for many decades…the steel glass lined ones.

I recall as a child my father showing how our defunct hotwater system worked and also the purpose of the anode (to corrode instead of the steel storage due to potential cracks in the glass coating).

Maybe the question is are anodes today more sacrifical than those in the past…namely, corrode faster and therefore need regular replacement to potentially prolong the storage tank life?

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…and how many of us have them checked or serviced ever, unless the service malfunctions? Mine is 20 years old and the only maintenance has been a new thermocouple 2 years ago, and an irregular pull of the safety pressure valve. Although our water quality is excellent the manual states the anode should have been inspected/replaced 12 years ago. At 20 years and counting I’ll go with a new service when this one gives up the ghost.

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No they aren’t inferior as regard their consumption rate, it is related to the surface area of potential corrosion that can occur. If more metal is exposed that is being protected by the anode then the anode will be consumed faster than if the other metal is still well protected and is less reliant on the anode sacrifice. So if like in @PhilT’s case that it isn’t leaking, the metal could either still be very well protected and the anode has not been completely consumed or if the anode has been totally consumed his HW vessel metal is thick enough that the corrosion that has occurred has not yet pierced the thickness of that vessel. The saltier the water the more corrosion potential exists and so a HW system located in a saltier water supply system will have the anode degrade faster than in a water supply area that has less dissolved salts in it (salts here mean any salt and does not solely mean Sodium Chloride).

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Could you kindly advise the make and type of your hot water system?

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Irrespective of the quality of the HW service the existance of the anode is not that well know. I think the last new electric powered storage HW unit I purchased 4 years ago, had a small label on the tank near the base in fine print. It’s rare in my experience to ever get the install booklet, which should also mention the anode needs to be inspected and replaced. I guess as plumbing is a prescribed occupation the unqualified owner is not permitted such specialist knowledge?

There needs to be an explicit requirement in the relevant Australian Standard to have a permanent suitably bold and legible label facing outwards on every installed service. One that includes both the need to relieve the relief valve and replace inspect/replace the anode. I’d suggest after 5 years. Perhaps that is now so?

Agree that the manufacturers benefit most from this lack of effective communication, as well as the retailers and plumbers. You even need a call out to pay an electrician to do the power when you need replacement.

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Well stated. I have even talked about the anodes with qualified licensed plumbers who were not aware of them.
As an electronics technician with some 50 years’ experience, I was well aware of the use of anodes in the electrorefining and marine industries
The manufacturers of these sub-standard heaters obviously still prefer to operate under the age old “caveat emptor” system.
One of my wife’s sisters and her husband live on an acreage in a rural area in FNQ where they are reliant on bore water in a historically volcanic area.
When we visited them recently, I broached the subject of the anodes, of which he was already fully aware, and he said that after replacing the original heater after they purchased the property around 28 years ago, he had bought 2 replacement heaters.
He now replaces the anodes about every 6 years and he said that when he removes them, they have corroded away to about the thickness of a pencil.
But the purpose of my post was to inform and warn people who are not aware of the anodes, as per your comment, so as to hopefully save them from some unnecessary inconvenience and financial burden.

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Vulcan Freeloader 300, 1998 vintage. FWIW the owner’s manual clearly describes the anode, the variants for different water quality, and so on.

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I installed and assembled my solar 30 evacuated tube HWS about 8 years ago, so it is about time to inspect the sacrificial anode (which is Magnesium metal). My tank is stainless steel and has only had rainwater in it, which is slightly acidic (pH <6), but with minimal hardness. It will be interesting to see how much the anode has corroded.

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I came across a good article regarding sacrificial anodes on a hot water sales & service businesses’ website and I have posted the URL below.
https://www.samedayhotwaterservice.com.au/all-about-anodes/
It would appear that Rheem and others are finally advising customers about the anodes. Too little, too late for us.

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When we bought our current home in February 2014, it had a Conergy AS315 solar hot water system which was installed the previous February.
The owner’s manual includes the following paragraph.
“The high quality vitreous enamel lined low carbon steel tanks have a sacrificial anode for long tank
life. This anode should be inspected every few years and be replaced when it has worn out. As a
minimum it is recommended that the anode be changed every 5 years.”
Whilst we have excellent water quality, considering the original owners paid $4,900 for the system including installation, I won’t be exceeding the recommended 5 year anode replacement.

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I have a 31 year old rheem lowline solar HWS installed in my home that my wife and I built 30 years ago and although the cylinder has been replaced now with a heat pump HWS I still have the original manual from 1987 and it advises that the rheem cylinder is equiped with an anode that should be checked every 5 years.

Just because the revelation about HWS sacrificial anodes are an epiphany for you that does not mean the same can be said for a lot of other people, as we have been aware of them all their home-owning lives.

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Your 1987 Rheem system may have information in the manual but our 1996 Rheem 400 litre dual-element electric heater certainly did not.
I read it from cover to cover after the system failed.

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I’ll leave you with that thought as a general statement on us males :smiley: :smiley: :smiley:

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So that means that irrespective of whether Rheem put the info about a sacrificial anode in your HWS manual it would have made no difference because you didn’t read the manual until after it failed?

No. It actually means that it was irrelevant as to whether I had read the manual or not as there was no mention of it and I do not have ESP.
It was unfortunate that I had not remembered the info in The Tap Doctors’ flyer, but when my wife’s late mother had them replace her kitchen sink flick mixer, they didn’t carry out an anode check as the HWS was a Saxon so the plumbers’ visit did not jog my memory.
When my wife’s parents bought the home in 1991, it was around 8 years old, and when we sold it to settle their estate in 2013 after they had passed away, the Saxon was still working perfectly as Saxons usually do.

Many thanks for all your input , I had never heard of this issue before.
I’ll be checking my Rheem.
Love the Choice community!

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Hi Techaddict. Glad that this thread has helped someone, contrary to one poster’s claim that everybody was fully aware of the anodes.
Do you have the owner’s manual for your Rheem or can you find a download for it? If so, is there any mention of the anode in it?
I actually posted this same subject many years ago on the now defunct Not Good Enough website so hopefully a number of owners have avoided unnecessary expenses over the ensuing years.

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As the old saying goes “When all else fails, read the instructions.”
But unfortunately, in this case there were none.

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