New Anode Not Threading In – Different Sizes and Threads?

The Tank New Anode Not Threading In – Different Sizes and Threads?

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  • #26420
    Corgry
    Participant

    Purchased a Mag Rod SKU8 here, to replace a 5 year old factory installed Aluminum rod in AOSmith ENT50 https://www.hotwater.com/Water-Heaters/Residential/Electric/ProLine/Standard/ProLine-Electric-Tank-Water-Heater-ENT-50/

    The old rod came out without issue, the new Mag rod is a good 18 inches longer, but when measuring the inside of the tank, it still has about 12 inches of clearance to go, so it’s not hitting the bottom of the tank and not screwing in.

    I also made sure that the deep socket I’m using is built up on the inside with some taped in bolts, so the socket isn’t interfering with it going in.

    I put the old AL rod back in, and it went in without issue, but before I did, I took a quick look at them, and at a glance they looked different, the old rod was slightly smaller. I didn’t notice until I actually measure them with calipers that the AL rod was tapered, and the new Mag rod was not. Also of note, that when the AL rod is inserted, it does not seat all the way down, the threads tighten about half way in before it won’t tighten anymore.

    I’m assuming that the AOsmith is just a normal 3/4th NPT, but maybe not? Or maybe the new Mag rod is incorrect? The AL rod at the start is 23.86mm, and at the top is 25.69mm. The Mag rod is 26.71mm throughout. If the AL rod stops threading in only half way, it’s not even getting to the 25.69mm mark, where the Mag rod is already bigger than that right at the get go.

    What am I overlooking here?

    Thanks.

    Anodes

    #26423
    Larry Weingarten
    Participant

    Hello, A thought. If you have a 3/4″ fitting around, like a “T” or a female adapter, try seeing if the new anode will begin to screw into that by hand. That’s meant as a test of the threads. If it works, than I’d run a 3/4″ tap into the port on top of the tank and see if it can be cleaned up. I notice that the threads on the old rod look rounded, which could suggest a problem with that port threads.

     

    Yours, Larry

    #26428
    Corgry
    Participant

    You are correct about the threads, I noticed that too, the old ones are definitely rounded where the new one is nice and sharp.

    Good call about the female fitting – I don’t have one, so I’ll grab one of those and maybe a male nipple to see if it threads in to the tank too, as well as a tap.

    Probably will be awhile till I report back.

    More and more messing with it get’s me nervous that I won’t be able to even get the old one back in and then I’ll have to buy a whole new tank.

    Thanks.

    #26429
    Randy Schuyler
    Participant

    I can understand your fear, but it shouldn’t come to that. Do make sure if you put the old anode back in that you use about six wraps of Teflon tape or it will leak. For what it’s worth, a 3/4-inch galvanized coupling is a common plumbing item that just costs a few bucks and would be an easy item to test with. Naturally, if it really won’t thread, then I’ll send you another.

    Randy Schuyler

    #26450
    Corgry
    Participant

    Update: I purchased a black steel pipe 3/4 FIP coupling, and a black steel pipe 3/4 MIP nipple.

    1) Those two items fit together as expected.

    2) The nipple fits in to the water heater.

    3) The coupling fits on to the old anode.

    4) The coupling does not fit on the new anode.

    So.. maybe an issue with the new anode? Looking at the threads I don’t really see a clear spot where a thread could start on it; maybe it was damaged somehow or had a factory issue?

    I was curious about why the old anode had a tapered thread, and the new one didn’t – I assumed that the NPT standard called for tapered threads, but when I just google “anode rod” all of them just appear to be straight instead of tapered, so I guess that’s not an issue.

     

    #26451
    Randy Schuyler
    Keymaster

    It’s probably time for me to send you another anode and a return label for the troublesome one.

    Randy Schuyler

    #26452
    Corgry
    Participant

    Thank you Randy, let me know how you would like to proceed, or if you’d like to continue via email.

    #26454
    Randy Schuyler
    Keymaster

    Just for the sake of completion, I did the rest by e-mail with Corgry.

    Randy Schuyler

    #26460
    Randy Schuyler
    Keymaster

    In the end, it transpired that a supplier sent a shipment of anodes that had straight threads that won’t screw into an anode port. Even with a magnifying glass, it wasn’t that obvious, and it had never happened before. I needed Larry Weingarten’s fine perceptions to be sure that was the issue. Luckily, he lives close by.  I’m still assessing the fallout, but Corgry decided to wait until the factory reworks the anodes and sends them back.

    Randy Schuyler

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