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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?

  • 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 '17 at 16:11
  • 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 '18 at 18:58
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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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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.

  • Good data point for a first answer, keep 'em coming! – ThreePhaseEel Dec 2 '18 at 21:32
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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 definately getting eatened 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? – ThreePhaseEel Nov 6 '18 at 0:14
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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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