Dear Dave,
How do you know when it’s time to replace the water heater anode? —Timothy
Dear Timothy,
You indicate the unit is a 2021 Rapid, which means it’s probably only one or maybe two years old. And since it has an anode rod, the water heater is a Suburban model. The anode rod acts as a sacrificial metal for the aggressive water action which creates protection for the tank. It should be inspected every year, and Suburban recommends replacing it when 75% of the rod has deteriorated.
This is a new anode rod.
This is the picture of yours.
And this is a diagram for reference from the Suburban Service Manual.
Although most of your anode rod is not at the 75% deterioration rate, the first inch is what concerns me. What could happen is the thin metal at this point could break inside the tank and would be almost impossible to get out.
Deterioration of an anode rod depends on several factors
Deterioration of the anode rod will differ depending on the quality of water, frequency of use, and maintenance. I would recommend replacing the anode rod with a new Suburban replacement. Other after-market rods, especially add-on electric heating element rods, can cause problems and void the warranty.
Before installing the new anode rod, I would also recommend to flush out of the tank using a flush wand like this one.
This will help flush out any sediment that could have settled in the bottom of the tank, as the drain is about 1.5” above the bottom. If the anode rod breaks off, this and the sediment at the bottom of the tank insulates the water from the heating source so it will not run as efficiently. It will also slow the heating process and could damage the tank’s glass lining by overheating the bottom of the tank.
If you are not using a filter at the water source, I would recommend either getting a Shurflo in-line filter, or a larger residential version that you can get a drop-in cartridge to hopefully filter out some of what is aggressively deteriorating the anode.
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.
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Hi Dave, I have a 2017 Forest River 34QS DP. Ours is a Atwood on demand water heater, does it have an anode?
Thanks
Snoopy
Hi Dave,
Atwood does not use an anode rod. Here is the description of the tank material from the Atwood service manual and how it acts with the chemicals in the water.
The Atwood water heater tank is constructed of a core of high strength aluminum. The interior of the tank consists of a 15% thickness of type 7072 aluminum (pure aluminum and zinc) that is fused to the core during the rolling process. This material protects the tank from the affects of heavy metals and salts found in waters throughout the country. It is anodic to these heavy metals and acts much like an anode in a steel glass lined tank except it will last much longer. There is also no need to replace an anode on a yearly basis
Opps, I did not see the “on demand”? I don’t think it does but will do more research.
Dave,
I just went through the Atwood On Demand Service Manual and there is no mention of an anode rod even in the entire parts breakdown schematic. For winterizing they just recommend blowing out the water with compressed air through a faucet or adding RV antifreeze “if recommended by RV manufacturer”. Another indicator is the warranty section does not mention it and especially doesn’t list it in the “not covered” section. I have a call into the Atwood tech support dept but have not gotten a call yet.
Hey Dave, thanks for extra research on my Atwood!
Snoopy
The galvanic series from high school chemistry says: Magnesium, aluminum, zinc, iron, in that order. Thus, magnesium anodes will protect all elements following. Zinc will protect iron. Similarly, if you use a zinc anode in an aluminum tank, the tank will be the anode and its’ life will shorten. If you read the Camco box holding a magnesium anode it says for Atwood water heaters.
Dave, The center core of the anode rod is steel and not “sacrificial” magnesium. I have seen some of my rods almost all just the steel core (overdue for a change) but no deterioration of the center core. I have never thought of it breaking off inside the tank but I don’t have your experience. Thanks for the heads up.
Steve,
We just had a reader send a question a couple weeks ago that had his anode rod break off and he had just checked it earlier with some corrosion. Now he can’t get the anode rod out of the tank. There is a ton of bouncing around as the unit goes down the road.