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For replacing an anode rod in a residential water heater, there seems to be some conflicting opinions regarding using teflon tape to prevent leaks. The rod manufacturer's instructions say to use it. Some people say to not use it as it prevents making a good electrical contact between the metals. Others say use it, the teflon tape will be cut by the bolt threads thus you will get an electrical contact.

What should I do? For the people not using teflon tape, how are you preventing water leaks?

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    Some type of joint tape or joint compound is going to be mandatory. And you are right; as the rod is installed tightly which it needs to be, plenty of contact is going to be made.
    – Paul Logan
    Dec 4, 2017 at 16:11
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    The manufacturer says use it they are the pros. PTFE or Teflon tape is soft and will be cut through so a metal to metal contact will be made if properly installed. I have changed many annodes over the years and have always used tape or dope.
    – Ed Beal
    Dec 2, 2018 at 18:58
  • You could add a grounding wire from the hex head of the rod to the tank somewhere to make sure.
    – Mike E
    Dec 20, 2023 at 17:45
  • Thread tape is actually melted by the intense heat and pressure generated when pipe threads are tightened, and does not prevent metallic contact.
    – kreemoweet
    Dec 21, 2023 at 0:52

5 Answers 5

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I just replaced my anode. I wrapped three layers of teflon tape and torqued it to 66ft-lb which seemed adequately tight. Online torque tables specified max 78ft-lb for 3/4 NPT. Resistance between anode hex head and outlet was 0.6ohm. This is essentially zero resistance. The lead to lead resistance alone is 0.2ohm.

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  • Good data point for a first answer, keep 'em coming! Dec 2, 2018 at 21:32
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Yes, teflon tape may reduce the effectiveness of the anode rode by electrically insulating the rod from the water heater chassis. The chances of it completely isolating it are nearly impossible though.

Use pipe joint compound if you have it, and use teflon tape if you don't.

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  • If you HAD to ensure that the anode rod actually was 100% insulated from the water heater tank, would you use (soft) Teflon tape and put it in the threads, where it will be rubbed through? Teflon tape will not provide an intact layer of insulation. Metal-to-metal contact will occur. Jun 13, 2023 at 15:31
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We have a 1988 hot water heater. We replaced the anode rod about 15 years ago and just replaced again today with a new magnesium rod. We used Teflon tape both times. The rod we took out today was definitely getting eaten away. I posted a video about this on YouTube, that shows the rod we just took out.

You can view that video at https://youtu.be/9Q6Gv0pM2os.

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    Perhaps you could take some still captures from the video and post them here to go along with the video link? Nov 6, 2018 at 0:14
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Use PTFE or Teflon tape if you want (otherwise a pipe dope or anti seize known for anode rod use), perhaps just two wraps of tape to support the need for the thread to cut through the tape so the current will flow. Optionally use an ohm meter if you are nervous and look for <0.6 (or something less than an ohm) after installed. I searched for stories of actual experience of insulated anodes that didn't function, https://www.forestriverforums.com/forums/f113/anode-rods-not-doing-much-213090.html suggests one. Not widespread, and that story is about theories, not measured and confirmed.

So, I read we should use 2 wraps only. Measuring the ohms requires the meter and good sharp probe tips that you can press through resistive oxides covering most metal surfaces... And access to the metal of the tank underneath the insulation. This quality check seems plenty optional.

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I replaced both of the anode rods in my 11 year old 50 gallon Bock water heater in January 2016. Bock recommends pipe dope not Teflon tape so the rods can be sacrificial instead of the tank.

After conferring with Bock, I used an impact wrench to remove the rods along with two wrenches and a band saw to cut the original 36" magnesium rods. The inside threads had been stripped by the service technician while trying to muscle them out. Original rods are cemented so an impact wrench is safer (I have a 700 ft-lb Milwaukee Fuel). I then used two wrenches to hold the rods in place while cutting them in half for removal so the bottom half does not fall into the tank.

I also removed any rust and painted the bottom with Rustoleum high-heat paint over rusty metal primer. I had to replace the linked anode rods because of only 18" of clearance.

Jan 2018, I just had a clean out and my 1989 Peerless with 2008 Beckett and my 2004 Bock with 1989 Bock/Wayne head are just fine. The hardest part was finding the hex head socket and the tapered tapper to restore the threads. There have been no leaks with the pipe dope.

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