Steam boiler anode rod

STEAM DOCTOR

Hi. This came up a bit in a recent discussion on the wall, as well as in the past. Is there benefit to installing an anode rod on steam boiler? Presumably, it would be installed in the wet return tapping. Is there any downside? Is it fair to assume that a powered anode rod would be the ideal choice?  Thanks for all the insights and info. 

Larry Weingarten

Hi, My understanding of the way anodes work is that they protect what they can "see". If you think of an anode as being like a fluorescent (now LED) tube, think of where that light shines inside of the boiler. That is the metal being protected, more or less. Also, an anode cannot protect where there is no water. It needs that electrolyte to function. The perfect anode would be a ball in the center of a spherical tank. That way the distance at all parts is the same, so everything gets the same protective current. Perhaps a boiler would benefit from multiple anodes arranged so they "lit up" all parts.

Yours, Larry

sbachman7117

Wow! This site is amazing. I just had this exact question in my mind. I waltzed over here and found a 3-day old discussion that "shines a light" on the subject.
I'm a landlord and I've been generally guilty of not properly maintaining my water heater tanks. After struggling to remove/replace an anode rod for the first time, I learned about powered anode rods. The idea of only needing to replace them once is appealing, so I'm considering using them in all of my properties.
Since the steam boiler in my home is much more valuable than a water heater, I wondered if I should also install one there. Thanks Steam Doctor for asking the question and thanks Larry for answering it!

ethicalpaul

it's a lot simpler to manage the PH of your steam boiler's water. Keep it 10-11 to minimize corrosion.

I think I have seen on this site that people found that anodes, powered or not, don't seem to have much if any effect on a water heater's life.

Larry Weingarten

Hi @ethicalpaul , maybe I’m misunderstanding, but to be clear, replacing sacrificial anodes in glass-lined tanks has let me get fifty years from tanks. It’s let me get well over twenty years in over softened water where clients used to get 2-3 years. I serviced tanks full time for about forty years and am certain that replacing anodes can greatly extend tank life. I also studied corrosion engineering and the science behind this is clear. 😉

Yours, Larry

ChrisJ

Larry Weingarten said:

Hi @ethicalpaul , maybe I’m misunderstanding, but to be clear, replacing sacrificial anodes in glass-lined tanks has let me get fifty years from tanks. It’s let me get well over twenty years in over softened water where clients used to get 2-3 years. I serviced tanks full time for about forty years and am certain that replacing anodes can greatly extend tank life. I also studied corrosion engineering and the science behind this is clear. 😉

Yours, Larry

Considering I changed my anode and the tank still leaked after 11 years and both anodes had plenty left on them, I don't know. The impression I got was anode or not, that tank would be junk in 10-12 years. Of course, this could also be because the anode is blocked by the flue.


Something else to consider is most of the corrosion in typical steam boilers appears to happen at, or just above the water line. Will an anode have any effect on this?

ethicalpaul

Larry Weingarten said:

Hi @ethicalpaul , maybe I’m misunderstanding, but to be clear, replacing sacrificial anodes in glass-lined tanks has let me get fifty years from tanks. It’s let me get well over twenty years in over softened water where clients used to get 2-3 years. I serviced tanks full time for about forty years and am certain that replacing anodes can greatly extend tank life. I also studied corrosion engineering and the science behind this is clear. 😉

Yours, Larry

That's good to hear Larry, I was just communicating what I had seen here on HH.

My ignorant homeowner thinking on the topic of gas water heater longevity is as follows: Aren't they supposedly "glass lined" so how are they all rotting out in 10 years anyway?

random12345

@Larry Weingarten is replacing an anode something a typical homeowner can or should attempt? I certainly haven't been doing it. But clearly it sounds like everyone should be. I also never understood what was meant by "servicing" a water heater in general and always thought it was best to just leave it alone. I have a few gas storage tank WHs.

Larry Weingarten

Hi @ethicalpaul , Glass lined means a baked on coating, very much like the glaze on a ceramic cup or plate. It’s thin and it’s not perfect. The glass has “holidays“ where the lining didn’t stick, or maybe cracked, or the assembly process leaves unprotected steel. That’s why anodes get used. Their job is to make the tank last for the warranty period.
High pressures cause cracks in the lining and temps over around 160F slowly dissolve the lining. The manufacturers know how to make very long lived tanks, but that’s not what most people want to buy.
Having enough sacrificial metal, properly placed, slows rusting down so much that the amount of metal loss cannot be measured. Corrosion engineers think in terms of mils per year, so if you are losing less than one thousandth of an inch per year, it doesn’t seem to count 🤓
Don’t know if I’m making things clearer or fuzzier 🧐
Yours, Larry