Clanking in hot water heater after changing anode rod

Rhino1

right after changing the anode rod, i hear a slight clanking/rattle when the water upstairs is used.

looking at placment of the heating elements and where the anode rod hangs down....could it the anode rod be rattling/touching the heating element?

the sound is definitely coming from inside the tank, and wasnt there before changing the anode rod.

also, the replacement rod was a flexible/sectioned mag rod.

i didnt make sure to completely straighten it when installing....i just fit in/lowered in/screwed back in...is it all flexed and klinking the element?

i also flushed the tank during this anode rod replacement

the old rod came out pretty well intact, no major pieces fell off etc.

i did cut 1 section off the replacement rod, it was same length of original rod when installed,

any thoughts please

Larry Weingarten

Hi, You clearly did the right thing in replacing the anode as much of the old rod has passivated, and isn't doing much work. About the noise, yes it could be the rod moving with water flow, touching an element. I have not had that experience, but see how it could happen here. Two choices come to mind. One is to replace the flex anode with a solid one if you can get it into the tank. The other approach would be to switch positions between anode and hot outlet. Ear plugs might not be a good long term fix… 🤔

Yours, Larry

Rhino1

Hi Larry,

Thanks for the response,

After over 5 years I was expecting the old anode possibly alot more depleted, but I guess our water isnt real hard. Im glad i did change without further delay.

I chose the sectioned mag rod because overhead clearance...and it was about cheapest magnesium i could get at that time.

I'll probably break down in short time and drain the tank some and pull the anode out and inspect, reinstall with more precision if possible.

Larry Weingarten

Hi, A tidbit that might be useful to you is that Rheem anodes are magnesium, but they install a resistor in the head of the rod to slow it down. Rheem anodes do not have a weld bump in the center of the head like other magnesium anodes have. If the water is pretty clean and not all that conductive, the Rheem anode can be prevented from working as it should by the resistor. The rod develops a hard coating like what I see on your old anode. So, check for that bump on the old rod. If it's not there, you cannot come to any conclusions about how hard your water is without testing.

It's tricky, but with limited overhead clearance, I sometimes bend the new anode in the middle, so that it will start into the tank, then insert halfway and straighten it. Then put it the rest of the way in. You can feel how straight it is or isn't by rotating it while the ends of the rod touches the sidewall of the tank.

Yours, Larry

DanHolohan

Larry, you’re a treasure. Thanks.

SuperTech

@Larry Weingarten that's fantastic information! I have never heard that before I am glad to have learned about that resistor this morning. This is the stuff that keeps me checking this website multiple times a day in my effort to learn more and become a better tech. Do any other water heaters have anode rods with a resistor like that or is that something only found in Rheem water heaters?

Larry Weingarten

Hi @SuperTech , I've only ever seen Rheem put in a resistor. I do like that they are skipping aluminum, but protection isn't as good as it could be in what I'll call rain-soft or naturally soft water. It's reason to check anodes for your clients, as it's a plumbing job that saves the client money. 🤑

Yours, Larry

ps. Dan, you made my day 🙏

Sol_Brother

Kudos for checking the anode and especially for writing the date it was changed. My father had a Post-It note at his desk saying, "If it's worth doing it's worth dating." which kept us scratching our heads about his attitude toward girlfriends until I understood it when later working alongside technicians who seemed to have the attitude that doing things like labeling valves or leaving a record of what they had done was giving away hard-earned information free to the next guy who comes along.

As you can see, the top half of an anode where water is hottest erodes fastest and is so far gone you want to replace it before the bottom even gets involved, so you might try cutting off another segment of your anode and see if the issue is just the cold water swirling in the bottom that is whipping the anode around.

One thing I was not clear about. You wrote it clanged "when water is used upstairs". I assume you meant hot water, but does the floor of the house the water is used on make a difference in the sound, or are all the fixtures upstairs?

Tom