Water heater, anode rod, electrolysis, and teflon tape

[BB_TX]

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

[BCSnob]

Aluminum tanks don’t need an anode rod.

[lwbfl]

mowermech wrote:
I'm lucky. My water heater has a plastic plug, no anode rod, so I do not have to worry about how it works.

My new one does too, YAY!

[BCSnob]

Our household hot water storage tank (the heater is out in the sunshine) doesn’t have an anode rod; it’s lined with cement.

[mowermech]

I'm lucky. My water heater has a plastic plug, no anode rod, so I do not have to worry about how it works.

[BCSnob]

What you’re describing is an Electrolytic cell (see link in previous post). However, current still needs to flow between the two metals in addition to ion flow through the solution; if that current is not provided directly or via an external current source (battery) the desired electrochemical reaction at the anode rod (and prevention of the oxidation at the heater metal) doesn’t occur.

[ScottG]

Hard to imagine a retired EE (like myself) not just using a DVM to verify continuity. I have done just that and even with 3 wraps of teflon tape, there is still zero ohms to chassis (tank). Same with pipe dope.

[lwbfl]

BCSnob wrote:

lwbfl wrote:
.....small positive charge attached to the anode, negative lead attached to the piece being cleaned.

Doesn’t this simply provide the current (electrons) needed to balance the ion flow in the solution (in place of directly electrically connecting the two metal pieces) and help drive the desired electrochemical reaction?

Sure it does, speeds the process and controls the flow, but there is no direct "electrical connection" for the same process, they are not screwed together like the element and the tank. The charge and solution simply quicken the reaction, they do not cause it. The point (well confused by this point)is that two metals can be isolated from each other and still be effected by electrolysis.

[BCSnob]

lwbfl wrote:
.....small positive charge attached to the anode, negative lead attached to the piece being cleaned.

Doesn’t this simply provide the current (electrons) needed to balance the ion flow in the solution (in place of directly electrically connecting the two metal pieces) and help drive the desired electrochemical reaction?

[lwbfl]

I use electrolysis to clean cast iron. There is no direct electrical connection between the two pieces (sacrificial metal and piece being cleaned) other than water. To make the process more efficient (which also rapidly increased the declining of the sacrificial metal or anodes)Sodium carbonate, Na2CO3, (also known as washing soda, soda ash and soda crystals) is added to the water. Both pieces are submersed in the solution, small positive charge attached to the anode, negative lead attached to the piece being cleaned. The piece being restored loses all organic materials and rust which gets transferred to the anodes. I suppose the point I'm trying to make with all of this is that no direct electrical connection is required for the chemical process other than the water.

[fpresto]

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.

While it may be often stated I have yet to see one that wasn't rapidly corrected. Everyone makes it too complicated. A voltmeter set to ohms will quickly prove that there is still continuity with the use of tape. you are dealing with microvolts so it takes very little contact.

[RKW]

The most convenient way found to change/monitor the anode rod was to join the threaded plug for the drain hole and the sacrificial anode in to a combo item. That's why the rod happens to be in close proximity to the threaded drain hole plug. The anode could have been located anywhere in the tank and still have worked well.

There is an electrical aspect to sacrificial anode that has nothing to do with threaded plugs. Because the anode is a different metal than the tank,there is a weak electric current in the water which is part of the process.

[BCSnob]

Ions flow in the water between the heater metal and the anode rod; electrons must flow between the heater metal and anode rod via an electrical connection (at the threads) in order to balance the charge being produced during electrolysis.

If you disconnect one side of your battery from the RV (no electrical connection) do you get electrolysis inside your battery (do your lights work)?

Read up on Galvanic cells in:
Encyclopedia of Physical Science and Technology (Third Edition), 2003

[Caesar_Ritchie]

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. To protect the metal of the water heater you need to take care while choosing the size of the water heater, there must be contact between the anode and the metal of the water heater.

[memtb]

I have always used Teflon tape, my anode rod .......continues to “sacrifice” itself!