Anode rod?

[RACKMAN]

Is it normal these days for there to be no anode rod in water heater tank? What prevents corrosion?

[Morich]

Different brand? Two major brands and each has a different way to deal with corrosion. I tend to prefer no anode as I have one now and it is a pain to hold it straight to rethread it into the tank after draining. The long shaft weight tends to pull it down too far for correct alignment. Other tanks without rods, I've always just swapped out the plug for a small drain valve. As far as I see, neither lasts any better than the other.

[RACKMAN]

Thanks...I've owned trailers for the last 10 years but never seen a tank without an anode rod...didn't know there was such a tank. Not sure on brand, I'll have to look, but what is the actual mechanism/design that prevents corrosion in a tank without an anode rod? Or is this just another way for companies to cheap out and have things fail earlier so you have to buy a new tank? Even the hot water tanks in residential homes have sacrificial anode rods...

[Morich]

That's where we each get such a small view of the world that we often get different ideas of the same thing!
My experience with anode rods has mostly been on home water heaters where only electrical heat has them as it is a function of the power being used. But on RV, the only time I've had a rod is the newish one that my current heater uses. I think it is a Suburban brand but the other major brand does not use a rod.
Since my other RV have always been almost old enough to vote and still had the original water heaters, I never felt a rod was needed. Apparently there are different ways to treat the inside of the tank to prevent corrosion, one uses a rod and the other coats the inside.
So have the home heaters that you have used, electrical or gas heaters? I've never seen a gas water heater that had a rod but that may be as simple as what part of the country as the water can be so different, place to place.
Or it could also be true that what I assumed was just a matter of not looking at the total picture and by luck of the draw, only getting what I've seen.

[l1v3fr33ord1]

Per this post over on iRV2:

Suburban HAS to use an anode rod due to STEEL Tank that is glass-lined BUT the glass-lining does NOT fully cover ALL interior surfaces plus it will have hair-line cracks....STEEL RUSTS

Atwood does NOT need an anode rod as their tanks a re ALUMINUM with a 'cladding' on interior that acts as an anode surface.

[jbrattain]

Attwood water heaters don't need an anode due to the metal the tank is made of.

[TeJay]

Anytime two dissimilar metals come into contact with an acid a battery is created. We feel it in our mouth when a fork touches a metal filling on a tooth. Ships/boats have their metal surfaces eroded away unless something electrically is done. Oil towers in the oceans also erode away unless the frame is electrically charged to prevent it.

The exact same thing happens inside a water heater unless a sacrificial anode is used or in the manufacturing process something is done to prevent the two metals coming in contact with the water.

In the case of the anode it is sacrificed instead of your water heater container.

Where does the acid come from? Most waters contain minerals/chemicals/iron etc and some of those can become acidic creating the current flow and corrosion similar to a battery.

The exact same electrical transfer principal or process is used to electroplate the surfaces of metals with gold, nickle, chrome, or silver etc, etc.

[Dibbsvtx1]

Anode rods are not necessary,

[TeJay]

Dibbsvtx1,

Don't know where you came up with that idea and giving incorrect or misleading information is not right. They are absolutely necessary to replace once they are eroded away if you have a hot water tank with a sacrificial anode rod.

[Oldchinahand]

We have an 10 gal Atwood. We also have a little inspection camera that plugs into our 'phones and other devices. Interesting to look inside things.

About 2x per year, we replace the heavily corroded magnesium anode rod (Camco) in our Atwood. If you are interested in the chemistry, here is a good read. https://pdhonline.com/courses/s118/s118content.pdf

Yes, Atwoods are aluminum lined. As others have said, the aluminum is intended to be the sacrificial anode. Its long term efficacy is dependant upon the specific alloy of the aluminum and the specific alloy of of the underlying steel. In any case, sooner or later, the aluminum will have done its self sacrificing job and then it will hot water against steel. And then corrosion will accelerate. Magnesium is further from steel on the galvanic series chart than is aluminum. It will corrode, the aluminum will not, the Atwood will last longer.

Do not cheap out and try zinc anodes. The aluminum will corrode first. (see the galvanic series chart) Zincs work great on steel, bronze and CuNi -- as in sea keeping vessels.

Fresh magnesium rods help us sleep better. Others may have other sleep aids.

Fair Winds and Following Seas

[Morich]

Interesting thoughts on the need of anodes. I have little experience with them and have rarely seen them other than in electric water heaters and RV but there is a logical explanation for why I have rarely seen them. I have never lived where the water was anything but alkaline due to high levels of limestone in the ground in all the places I have lived for more than a few months. If acidic water is a factor, living between the mountains is likely to mean a much different situation than living on either coast but in RV which may travel to all sorts of water situations, the anone makes more sense.
In the Central Texas location for now, we have PH of 7.8 from the tap and with very high GH and KH, the PH is very hard to move due to the natural buffers.

[Old Crows]

Yes... here in "Heart of Texas Hill Country" the water is nearly stone and has a high Ph. You really need a water softener or conditioner on your house system if you want it to last.



RVs? Depends on your WH. An Atwood has an aluminum tank. Atwoods have a nylon drain plug and IRRC, they don't recommend an anode. (You have to read the very fine print in the Atwood manuals!) Their design supposedly does away with the need for an anode in the tank. Suburbans have another type (steel??) and you need an anode. Also, the plumbing in a modern RV is almost always PEX and there are few metal to water contact areas where you can get corrosion and erosion of the metals. The concern might be lime scale build up in the system if you are using a lot of softened water.



That said.... I've used a petcock/anode plug in my Atwood. The anodes last about 1 to 1 1/2 seasons depending on how you use the RV. They are shot when you take them out. I just went back to the OEM nylon plug and used one of those 'wands' to flush out the tank. Very little sediment and junk flushed out of the tank.



After quite a few years of using an anode, I've really not seen any advantage to it in my RVs. And the 'petcocks' end up getting pretty much frozen in place making them hard to operate. Much easier just to yank the nylon plug and lett'r rip. (Which helps to flush the tank with high flow rates!)



And, as much as possible, I try to refill my water tank from my house's conditioned water system when ever possible. On the road I take what I can get when and where needed.



I hope this helps.

[calendarboy]

Originally Posted by Morich

That's where we each get such a small view of the world that we often get different ideas of the same thing!

... anode rods ... only electrical heat has them

... never seen a gas water heater that had a rod ...

With an office, several rentals, mountain cabin, and homes I have changed out many water heaters.
I have never seen a residential water heater that didn't have an anode.

Normally, I remove the anode and replace it with a magnesium version. I then remove the nipple for the hot outlet and replace that with a combo outlet/anode version.

The last gas version I installed did not have a dedicated anode. So, it looked like it did not have one. However,the outlet included an anode. It was aluminum so I replace it with a magnesium version.