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Open Roads Forum  >  General RVing Issues

 > Water heater, anode rod, electrolysis, and teflon tape

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BB_TX

McKinney, Texas

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Posted: 01/15/19 11:41am Link  |  Quote  |  Print  |  Notify Moderator

It is often stated on RV forums that you should not use teflon tape on the anode rod threads as it could interfere with the electrical contact. Being fairly knowledgeable in electric (retired EE) and limited knowledge of electrolysis, something just did not sound right. And my little engineering brain can't live like that. And finding nothing definitive by googling, I went directly to the source. I e-mailed Suburban with my question, "Does the anode rod threads have to make electrical contact with the water heater threads for the anode rod electrolysis to work properly?"

I got a quick reply from an assistant service manager at Suburban as follows;

"The answer is No. The metal threads do not need to make contact with each other. Electrolysis is the chemical reaction that takes place inside the tank and has nothing to do with the threads. I've attached some Suburban water heater videos to this email that I believe you'll find very interesting."

And here is the video they attached, actually using the tape. So those who use teflon tape can rest easy.

Suburban water heater video

donn0128

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Posted: 01/15/19 12:29pm Link  |  Quote  |  Print  |  Notify Moderator

Teflon tape is a wonderful convenient thread lubricant. The problem is 98% of people have no idea how to properly use it. They think more wraps is better, whe just the opposite is true.





wildtoad

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Posted: 01/15/19 12:50pm Link  |  Quote  |  Print  |  Notify Moderator

They must be under the impression that the tape prevents leaks.


Tom Wilds
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fj12ryder

Platte City, MO

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Posted: 01/15/19 01:01pm Link  |  Quote  |  Print  |  Notify Moderator

wildtoad wrote:

They must be under the impression that the tape prevents leaks.
And a correct impression that would be.

"Plumber's tape, often called Teflon tape, helps you get a watertight seal on threaded pipe joints." But it's not an insulating tape, there will still be metal to metal contact in places.


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BB_TX

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Posted: 01/15/19 01:04pm Link  |  Quote  |  Print  |  Notify Moderator

The success of any plumbing project hinges largely on the quality of its joints. Threaded connections between metal or plastic parts can be particularly problematic if not sealed properly. Teflon tape and pipe dope are used to fill voids between male and female threads to make joints leakproof and to prevent metal parts from rusting together. People often use pipe dope on top of Teflon tape, but some manufacturers say there is no benefit to that usage and that Teflon tape and pipe dope perform the same whether they’re used individually or together.

mobeewan

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Posted: 01/15/19 01:12pm Link  |  Quote  |  Print  |  Notify Moderator

Teflon tape actually seals the threads from leaking by being crashed within the threads and being squeezed into the gaps and imperfections in the thread to thread contact between the tank threads and the plug threads. This keeps the water from working it's way through the thread spirals and leaking from the threads.

Teflon tape does not stop contact between the threads since it is crushed and squeezed into the imperfections. Otherwise if Teflon tape was so great at breaking the "electrical contact" between the tank
threads and plug threads the tape would still be intact when removing the plug and not crushed into spiral shaped remnants requiring removal before applying new tape.

wgriswold

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Posted: 01/15/19 01:45pm Link  |  Quote  |  Print  |  Notify Moderator

I have checked the electrical conductivity between the sacrificial anode and the metal of the water heater and Teflon tape does not prevent it.

I believe that, in order to protect the metal of the water heater, there must be contact between the anode and the metal of the water heater.


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donn0128

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Posted: 01/15/19 02:04pm Link  |  Quote  |  Print  |  Notify Moderator

No. According to Suburban the anode rod uses a chemical reaction NOT electrical.
It could be totally isolated from any metal and will still perform its intended function. Think sacrifical anodes on a boat for an example.

wgriswold

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Posted: 01/15/19 02:18pm Link  |  Quote  |  Print  |  Notify Moderator

donn0128 wrote:

No. According to Suburban the anode rod uses a chemical reaction NOT electrical.
It could be totally isolated from any metal and will still perform its intended function. Think sacrifical anodes on a boat for an example.


The reaction is an oxidation/reduction reaction and involves the transfer of electrons from the anode to the cathode. Simply, oxygen is looking for electrons and finds them at the steel of the heater or the sacrificial anode which is then dissolved. There must be a way for electrons to flow from the sacrificial anode to the metal being protected.

On my boats the zincs were always screwed into the metal being protected, thereby allowing contact between the zinc and protected metal.

Do you have a reference for the Suburban statement. I can't find it on their site.

This is interesting, maybe I am wrong. If so I would like to figure it out.

Thanks.

donn0128

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Posted: 01/15/19 02:56pm Link  |  Quote  |  Print  |  Notify Moderator

Actually a guy posted a response from Suburban on another RV forum. Also based on wikipedia a maximum of three wraps of teflon tape is correct use. Like wiki explains the teflin tape once wrapped and the parts screwed together the teflon fills holes in the metal, but there is still plenty of surface for electrical contact.

Found this too
The role of the sacrificial anode rod

The anode rod is the most important factor in determining the life of your water heater. An anode rod is a steel core wire surrounded with one of three different metals. These metals include aluminum, magnesium, and zinc. The rod is screwed into the top of your water heater and protects your water heater from rusting. When the tank is filled with water the anode rod sacrifices itself to protect the exposed steel of the water heater, through a method called electrolysis. Electrolysis happens when there are two pieces of metal connected inside of water, the process makes the anode rod corrode in place of the exposed steel in your water heater. During this process the more noble (less reactive) metal will corrode over the less (more reactive) noble metal. Aluminum, magnesium, and zinc are all much less noble than steel, meaning they will corrode before the steel, which is why they are used for anode rods.

* This post was edited 01/15/19 03:28pm by donn0128 *

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