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Old 02-07-2009, 11:21 PM   #1
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Teflon tape or pipe dope an anode rod?


The question of replacing anode rods in a water heater came up in another thread.

My question is this:

How can you use pipe dope or teflon tape on the threads of the new anode rod without compromising the electrical connection between the anode and the metal tank?

I suspect the answer to this question is that if you tighten up the anode rod well, there will always be some metal to metal contact between the threads. If there wasn't, your connection isn't tight enough.

And, the current flow out of the anode rod is so tiny that you wouldn't need a very good electrical connection between the anode and the tank.

Does anyone have any ideas on how best to install the anode rod to ensure good electrical conductivity between the anode rod and the tank?

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Last edited by Nestor_Kelebay; 02-07-2009 at 11:30 PM.
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Old 02-08-2009, 06:39 PM   #2
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Teflon tape or pipe dope an anode rod?


Still learning!
Didn't know that there was a concern for electrical properties on replacing anodes.

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Old 02-08-2009, 10:00 PM   #3
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Teflon tape or pipe dope an anode rod?


Quote:
Originally Posted by Nestor_Kelebay View Post
The question of replacing anode rods in a water heater came up in another thread.

My question is this:

How can you use pipe dope or teflon tape on the threads of the new anode rod without compromising the electrical connection between the anode and the metal tank?

I suspect the answer to this question is that if you tighten up the anode rod well, there will always be some metal to metal contact between the threads. If there wasn't, your connection isn't tight enough.

And, the current flow out of the anode rod is so tiny that you wouldn't need a very good electrical connection between the anode and the tank.

Does anyone have any ideas on how best to install the anode rod to ensure good electrical conductivity between the anode rod and the tank?
There exists conductive tape, although it may not be meant for plumbing applications.
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Old 02-08-2009, 10:12 PM   #4
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Teflon tape or pipe dope an anode rod?


I don't think this is a concern as the tape or dope would fill the low points of the threads. When I have removed threaded fittings in the past the tape / dope did not cover the entire thread of the fitting.
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Old 02-08-2009, 11:42 PM   #5
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Teflon tape or pipe dope an anode rod?


Yeah, Reilly's right. Whenever I've removed taped connections, the crests of the thread were bare, and all the tape was packed into the thread valleys.

Downunder:
Quote:
Didn't know that there was a concern for electrical properties on replacing anodes.
If your anode rod isn't in electrical contact with the steel tank, then effectively you don't have an anode rod. That's cuz the anode rod uses galvanic corrosion to protect the tank. Basically, it corrodes instead of the tank (just like the zinc coating on galvanized sheet steel protects the underlying steel from corrosion). And, to have galvanic corrosion you need three things:

1. two different metals
2. those two different metals also in electrical contact, and
3. those two different metals also both in contact with the same electrolyte to complete the circuit

If you don't have all three, you won't have galvanic corrosion of the anode, and so no galvanic protection of the steel tank. So, having electrical contact between the anode rod and the steel tank is critical. Without it, you may as well have a steel plug in the hole instead of an anode rod.

That's why I was concerned about the teflon tape or pipe dope interfering with that electrical contact.
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Last edited by Nestor_Kelebay; 02-08-2009 at 11:51 PM.
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