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 Posted: Mon Nov 14th, 2005 12:26 am
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anode101
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After reading your site, which has a lot of great information, I wondered about the page that told of the use of teflon tape on the anode rod.  It said that there was a small amount of current that would flow through the teflon tape.  After pondering how you'all measured this current, I decided to run a test.  I got my mA meter out and placed one lead on the top of the anode hex head and the other lead to the tank.  No suprise there, cause, I guessed there would be no current.  That meant that there was a good contact between the anode and the tank.  Now, I had a piece of anode that was cut off a longer rod to fit a tank.  I filled up a steel coffee can with water and conneted the mA meter to the small piece of anode and the other to the can.  Not touching the anode to the can, there, I did see a small amount of current, about 20mA.  As soon as I touched the anode to the can, the current dropped to zero.  Therefore, to test if the teflon tape is causing a problem, all one has to do is place a mA meter between the tank and the hex head of the anode and see if there is no current reading.

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 Posted: Mon Nov 14th, 2005 01:03 am
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eleent
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Hello:  I'm not sure you actually posed a question, but to clarify... When an anode has been wrapped with teflon and tightened into place, many times I've used my trusty volt-ohm meter to check, in the ohms scale, that I still had continuity from tank to anode.  I always have.  So, I know there is a path for the current to follow.  Were there no path, the anode could not protect the tank.

Yours,  Larry

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 Posted: Mon Nov 14th, 2005 01:27 am
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anode101
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My question was how does one actually measure the current through the anode to tank circuit?  True, a VOM set to ohms will measure the continuity, which I did measure.  Very little resistance if not zero ohms.  This did verify that the teflon tape posed no problem.  So, you are correct to use a Ohm meter to check the circuit.  After reading many internet sites, there was concern, by myself, about the use of teflon tape and it's effect.  One site would say don't use it.  One site would say only a turn or two.  Another site would say it's OK.  I used seven turns of tape and it posed no problem.  I recently installed a new water heater after only two years.  This one had a leak at the anode rod threads.  The first water heater also leaked after two years.  So, I am very concerned about the anode.  I have another water heater in the house and it's anode was replaced six months ago.  No problem and going on five years now.  Thanks for the time to talk!.

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 Posted: Mon Nov 14th, 2005 05:51 pm
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eleent
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Hello:  I'll guess the reason why you want to measure anode current is to see that it's working.  The National Association of Corrosion Engineers would suggest installing a reference electrode near the bottom of the tank to get actual current density.  For mere mortals like me, simply knowing that the anode is electrically connected to the tank, combined with periodic visual inspection of the rod itself is an easier way to know what's going on inside the tank.  Water quality and conductivity, the condition of the tank and its lining, tank size and geometry and anode metal and its purity all affect how long an anode will last.  I suggest checking a new anode in one or two years and see how fast it's being used up.  From there, you can make an educated guess when the rod will have six inches of exposed core wire.  That's when it should be replaced.  Hope that helps. ;)

Yours,  Larry

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 Posted: Mon Nov 14th, 2005 08:33 pm
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anode101
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Yes, I am now certain I wanted to see if I could measure the current to check if the anode is working.  I would think that as the rod is spent, the current goes down.   The suggestion of adding another electrode near the bottom sounds too much for me to take on.  I too, being a mortal, would like to keep it simple.  Your suggestion of pulling the rod every year sounds like a great one.  Next time I will schedule a draining and flushing and then pull the rod and see, now that I have teflon tape on the threads which will make it a breeze.  Thanks for the help!

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 Posted: Thu Dec 8th, 2005 06:51 am
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even if the teflon could electrically isolate the anode, it is submerged in water,  therefore completing the circuit, wouldn't it work either way? ???

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 Posted: Thu Dec 8th, 2005 04:56 pm
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eleent
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Hello Greg:  Yes there needs to be current flow through the water for the anode to work, but that's only half of the circuit.  The connection to the tank is still needed to complete the circuit.  It would be like hooking up a light bulb with only one wire. :cool:

Yours,  Larry

Last edited on Thu Dec 8th, 2005 04:57 pm by eleent

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 Posted: Sun Jan 1st, 2006 03:51 pm
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scumbdyoit
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On teflon tape, anode inspection, and more anode questions:

Speaking strictly as an interested amateur, with no claim to technical expertise: teflon tape is obviously pretty soft stuff.  Tightening any threaded metal to metal connection wrapped in teflon tape is going to cut through the tape in many places, creating lots of metal to metal contact for an efficient electrical connection.  Teflon tape flows and deforms easily under pressure, and its function is to fill in the the minute gaps among the threads to prevent fluid leakage, which it does very well.

The USe and Care Manual for my new Rheem 40-gal 12-yr-warranty water heater (sold by Home Depot as a GE brand) tell me (the homeowner) to remove and inspect the anode rod annually, and replace when more than 6" of core wire is exposed.  (See http://www.rheem.com/Documents/ResourceLibrary/UseAndCare/RheemResGas/ResGasFuryGuardian_AP13311-1.pdf, p. 19, under "Routine Preventative Maintenance."  This is a slightly older version of the owners manual; mine is dated 01/05.)

A principle difference between the 6-year warranty and the 12-year warranty on the water heaters is the anode rod.  The 6-year warranty uses the R Tech Resistor Magnesium Anode Rod 44" long x .700 dia SP11309C (single), while the 12-year warranty uses the R Tech Resistor Magnesium Anode Rod 44" long x .900 dia SP11526C (single).  (See http://www.rheem.com/Documents/PartsCatalog/WHPartsGuide2006_PPC101R1.pdf, pp. 39 (parts chart) and 7 (description of anodes); printed page numbers, not PDF file page numbers.)   The 12-year anode should have roughly 65% more metal (0.636 sq. in. cross section, vs. 0.385 sq. in. cross section).  Is my interpretation of the information correct?  Could the astute homeowner save the extra cost of the 12-year warranty, and rely an the annual inspection of the anode rode to extend the life of the 6-year-warranty water heater, replacing the anode with the more robust anode when the time came?

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 Posted: Sun Jan 1st, 2006 06:43 pm
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eleent
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Hello:  We need more "interested amateures" like you who seem to enjoy digging for info :cool:.  
One gets more life from a tank, with less frequent anode inspection, by putting more anode metal in the tank.  You can use bigger diameter anodes or more of them.  I've long suggested getting a good, well insulated tank and adding a second magnesium anode as a less expensive way to get a heater.
I once worked on a 30 year old electric heater that had come with a 1" (commercial size) anode, even though it was a small residential tank. With more anode in the tank, the need for anode inspection becomes less frequent.... often in the five or six year range.  Still, the relief valve should be looked at much more often than that.  Casting a glance at the heater periodically will also catch small leaks, before they do serious damage.

Yours,  Larry

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 Posted: Sun Jan 1st, 2006 06:50 pm
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elenano
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It would seem you haven't explored the rest of the site. We strongly advocate installing a second, combo rod in the hot port before installation. That's usually cheaper than getting the 12-year-warranty tank -- and superior. Then you've got 100 percent more anode instead of 65 percent.

I might note that the Rtech rods have a resistor in them to slow down the function of the anode, a strategy for ensuring that the anode isn't consumed in aggressive water before the warranty ends. Aluminum anodes are another such strategy. Rtech rods have about the same driving current as aluminum.

There is a great deal elsewhere on the site that I don't want to repeat, but it's better to have standard magnesium anodes at full driving current, especially in naturally soft water, than aluminum or reduced current magnesium. And regardless of whether it's Rtech or plain, one or two, aluminum or magnesium, people should check their anodes once in awhile. Otherwise, like a friend of mine, they're liable to go off on vacation and return to find 700 gallons of water in the basement. And the basement was living space....

Randy Schuyler

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