UPDATE! RV Water Heater Anode Rods

TheRVgeeks Annual Maintenance, Maintenance, Plumbing, Updates & Upgrades, Water & Sewer 6 Comments

If you’ve seen our previous 2 videos about flushing RV water heaters, you’ll know we’ve talked quite a bit about anode rods. Generally, Suburban brand water heaters require an anode rod to protect the steel tank from corrosion. The rod is made of a metal that sacrifices itself, so that corrosion will attack the rod before attacking the steel tank. Atwood brand water heaters generally don’t use anodes because their tanks are made of aluminum.

After watching this update, you’ll know why we highly recommend using the Suburban OEM magnesium anode rod. They’re not expensive, and you can find them on Amazon here.

We have a Suburban heater, and a problem arose when, after only one year, our original equipment anode was rusted into place so badly that we almost couldn’t remove it. We actually ended up breaking a socket wrench in the process.

As a result, we installed an aftermarket anode with brass threads, that screws into an outer brass sleeve. The brass-on-brass design made it (pardon the pun) a lock to unscrew easily. Even though the OEM anode is magnesium, and the aftermarket rod was zinc and aluminum, it should still have worked properly, as those metals should still corrode before the tank did.

In carrying out its sole purpose (prolonging tank life), an anode should decay a considerable amount. We used the aftermarket rod for two full years (with an inspection at the halfway point) and it didn’t look much different than when it was new.

So, last year we opted to go back to an original Suburban anode, choosing to run the risk of being unable to remove it, over the risk of the early demise of our water heater. Although we’re running late on our spring maintenance tasks this year, 16 months later… the results are in.

First, the OEM rod came out easily, without a problem. Second, the OEM rod sacrificed itself the way it’s supposed to. When we look at them side-by-side, it’s a no-brainer which one we’ll rely on to protect our Suburban water heater from now on.

Here’s what Suburban has to say about anodes:
“All Suburban water heaters are protected by a magnesium or aluminum anode to prolong the life of the tank. Under normal use, the anode rod will deteriorate. Because of this, we recommend it be replaced annually or when consumption or weight loss of the rod is greater than 75%. Note: Water with high levels of iron and/or sulfate will increase the rate of deterioration. To extend anode life, drain water from tank whenever the RV is not being used. Avoid any extended time of non-use with water in the tank.”

Learn how to Flush Your Water Heater (Suburban and Atwood).


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Comments 6

  1. I’ve watched you water heater videos and am a little confused. I thought the reason you switched your bypass on was to PREVENT water from entering your water heater. Is that the reason you use the water pump to fill it instead of the city water supply? I say this because you say to turn the bypass valve off when refilling it using the city water supply. Am I understanding you correctly?

    1. Post
      Author

      Hi John. Not sure we totally understand your question, but we think we can explain the “bypass” vs “normal operation” position of the bypass valves (we’re using “bypass” vs “normal operation” to make it clear which mode we’re talking about, as opposed to bypass valves “on” or “off” which can be unclear, since “bypass on” would refer to the stopping of water coming into the heater, despite the “on” in the term.

      We can use our winterizing kit (which is a separate set of valves) for three different things: 1) Drawing anti-freeze into the plumbing system, 2) Drawing bleach into the fresh water tank for sanitizing, and 3) Drawing vinegar into the water heater to flush scale out of it. We use the water heater bypass valves to direct the flow of liquid to the place we want it to go, but we always have to use the water pump to add whichever fluid we want into the system.

      When we want to winterize, we “bypass” the water heater to block anti-freeze from getting into it (it’s not needed, or wanted in there). Same thing goes for drawing bleach into the fresh water tank, where again, we “bypass” (block) the water heater to keep bleach out of it (again, we don’t want bleach in there, since it’s a nuisance to flush it back out). The only one of these three tasks where we want fluid drawn into the water heater is for vinegar flushing. So in that case, we leave the bypass valves in “normal operating” mode (don’t bypass/block).

      Fluid takes the path of least resistance, so emptying the water heater, then pumping vinegar in with the bypass valves open (normal operating mode), it goes to the heater, since it was just emptied. It’s the water pump that draws fluid up through the winterizing kit, but it gets directed into the empty water heater because it’s the path of least resistance (empty / full of air). If we were to “bypass” (block access to) the water heater, the vinegar couldn’t get into it. By the same token, bypassing the heater, then opening the “fresh tank fill” valve directs fluid, again, along the path of least resistance…. this time it’s the fresh water tank, which has plenty of space in it to add water. That’s how we use the same winterizing kit to add bleach for sanitizing.

      After drawing vinegar into the water heater using the winterizing kit, we finish filling the heater by turning on the city water. We also use the city water to flush it out when we’re done cleaning it.

      Hope this isn’t too confusing! It might help of you watch just one video about water heater flushing, because the triple usage of the winterizing kit can make things confusing.

    1. Post
      Author

      Hi Betty Lou! When you say “the water is still only getting warm”… does that mean you were having that problem BEFORE changing the anode rod? Because the anode rod doesn’t have anything to do with heating the water. It’s a protective component that sacrifices itself to protect the metal inside the water heater’s tank. If you’ve been having trouble with the water heater not getting the water hot for a while now… then something else is wrong. It could be any number of things:

      (1) If you winterized your RV and just de-winterized it, it’s possible that you left a valve somewhere in the wrong position… and cold water is mixing with the hot so you only get warm.

      (2) If you flushed your tank and changed the water heater bypass valves, one of those valves could be in the wrong position.

      (3) If you used your outdoor shower, it’s possible you left the valves open and just closed off the switch on the shower head/handle… which (believe it or not) allows the hot and cold water to mix so you only get lukewarm water throughout the RV (we have a video about that here: https://www.thervgeeks.com/miscellaneous/water-heater-fail-newbie-mistake/ )

      If you open up the over-pressure/over-temperature valve and check the water that comes out (be careful!!), is it HOT? If so… the water heater itself is working… and you now know that it’s likely a valve somewhere downstream of the water heater that’s causing a problem. If it ISN’T hot, then it’s a problem with the water heater itself… which could be the thermostat or circuit board.

      Let us know answers to any of the above and maybe we can help you get this resolved.

  2. Why do the RV anodes corrode so quickly as compared to the home water heater anodes? Been working on residential water heaters since 1978. Your aftermarket anode looks like what I would expect after 2 years. I just pulled our anode after only 2 months and it is very sacrificed. https://i.imgur.com/Dtms3DH.jpg So I ordered a new one from just like you recommend.

    1. Post
      Author

      Hi Kenneth! That’s a great question about residential vs RV water heaters, and one that I’ve wondered about myself. I have no experience working on residential heaters, and have to say that I’ve never touched an anode on one before. Maybe I was simply ignorant about the need, maybe most don’t require it (aluminum tanks, like Atwood RV heaters?), or some other factor. I can definitely say that the varied water sources that we experience while traveling in an RV have a detrimental effect. That’s especially true when spending much time in the Desert SW, where the water quality is pretty bad. I’m sure that some parts of the country have it a lot worse than others. When we spend more time in the Pacific NW, where the water is generally very good, our anodes usually last longer, and a lot less debris comes out of the heater during our annual flush (see our most recent video for details on this year’s follow-up inspection). Fortunately, the anode is cheap to replace, and we have it out for cleaning once a year anyway. The price and effort to replace the entire heater is so great that we have no problem ponying up for a new anode as needed!

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