? about new water heater. No rotten egg smell?

[WorthFlorida]

All interesting information. I'd be nice if the water heater manufacturers come up with ANSI or NSF specifications to how to handle this dilemma.

What I'm getting out of all of this discussion is powered anode rods may have an unlimited source of electrons and they travel anywhere in the media it's sitting in. A typical anode rod in a water heater may be the full length of the tank because it is sacrificial and there is a limited amount of electrons to bleed off before it is depleted. More metal, longer life? Not sure of the distances inside a water heater between the anode and the metal would affect its life all that much.

 

[VincentV3]

The only place the anode is needed is where there is an imperfection in the glass lining. If we were to assume the only flaw was at the bottom of the tank, a short anode could protect that. If we presume many little flaws distributed around the tank, the available current will be more at the areas closer to the anode.

This statement is correct except for one small thing in the last sentence. Since it is an imposed current anode, the anode is forced to make electrons. These electrons will then polarize the places at risk on the tank. It's true that the electrons will protect the top of the tank first, because they go to the places where it's easiest first. However, when the place is going to be polarized (a few days), the electrons will move to the next place and so on until the tank is completely polarized. The sacrificial anodes are longer in order to give the necessary electrons to protect the tank over a given period. But every time the anode will give an electron, it will sacrifice some of its material.

As mentioned above, the only impact of the length of an imposed current anode is life expectancy. The anode could be much shorter, but it would not last that long.

I find http://www.dtic.mil/dtic/tr/fulltext/u2/a081707.pdf printed page numbers 10..13 showing water tank protective anodes for a water tank. The illustrations indicate that the range of protection is limited for a given anode. It is an old document, but they knew what they were doing back in 1979 too.

In this document, it is important to understand that the tank shown has a capacity of 100,000 gallons. It is normal for the number of anodes to be higher, otherwise they would not be able to protect the tank for the desired number of years.

Our different models have been designed for tanks ranging from 10 to 120 gallons. The number of mA sent as well as the quantity of material present on the anode make it possible to maximize the cost of the anodes while offering an optimal protection for at least 20 years.


You can contact us for more information or more specific questions at info@corroprotec.com

 

[Sponsor]

 

[VincentV3]

What I'm getting out of all of this discussion is powered anode rods may have an unlimited source of electrons and they travel anywhere in the media it's sitting in. A typical anode rod in a water heater may be the full length of the tank because it is sacrificial and there is a limited amount of electrons to bleed off before it is depleted.

Exactly!

 

[Reach4]

What I'm getting out of all of this discussion is powered anode rods may have an unlimited source of electrons and they travel anywhere in the media it's sitting in.

That would be the case with a pure voltage source-- unlimited electrons can be sunk into the anode.

But consider that you have a resistive electrolyte (the water). Presume the voltage is zero at the tank surface, and maybe 1.9 volts at the anode.

What do you think the voltage would look like at various points in the tanks? If we model the tank as conductive, we would get one profile. If we model the tank as being covered by glass over 99% of its area, with the gaps spread out, then we would get a different profile.

This could be tried out as a science fair experiment. Use a voltmeter probe to map the voltage at the various points. Novel... much better than the paper mache volcano that passes for science.

 

[VincentV3]

But consider that you have a resistive electrolyte (the water). Presume the voltage is zero at the tank surface, and maybe 1.9 volts at the anode.

What do you think the voltage would look like at various points in the tanks?

Exactly, it depends on the resistivity of the water. That's why we use a current rectifier. Here are the specifications: Voltage output: 0 to 24V (the voltage will vary depending on the resistivity of the water to ensure a current of 15ma)

Sending too much current could create hydrogen in the water and reduce the life of the anode.

 

[Phog]

Corrosion is a surprisingly complex phenomenon. I will give a real world example to illustrate.

I am currently working on a project that involves some equipment installed in a pair of undersea pressure vessels, one is made out of 316SS and the other from 5055 aluminum. They have a ground strap connecting them, and they are separated by perhaps 12". They are submerged in a freshwater pool, which is in our research lab. There is a high galvanic potential between these two materials and the equipment inside the pressure vessels is very expensive.

We have installed a Gamry potentiostat whose purpose is to prevent corrosion to the aluminum. That stat is a $10,000 laboratory-grade piece of equipment intended specifically for corrosion protection. It has a separate reference electrode and is setup to drive current through a marine zinc (which I believe is actually magnesium -- I will have to ask the research scientist next time I see them) to achieve the cathodic protection. Active water heater anodes are basically a scaled-down home version of this system.

What has stuck me is how sensitive the system is, even with this sophisticated level of equipment. In the first failed try, the reference electrode & anode were located close to the aluminum vessel, but on the opposite side (away from the 316SS). This ended up only offering protection to the side of the aluminum vessel facing the reference electrode, leaving the side facing the 316SS vessel not well protected. Even with the impressed current and the lab-grade equipment, there was a clear corrosion gradient observed after only a few days from one side of the aluminum vessel to the other. The system has been tuned now; the reference electrode was relocated to an optimal point (between the two vessels) & has been changed from a single point salt-bridge type to a long, skinny metal bar. It took several tries to get this right.

To design a system for a water heater, the same basic principles apply -- there will be a high sensitivity to both tank geometry and to water conductivity. In other words, identical water heaters with identical cathodic protection systems might perform differently in two different cities due to the different characteristics of the city water; and the same identical powered anode system might perform differently in two different water heaters in the same city water due to geometry differences, etc.

In any active anode such as those offered by CerAnode, Corro-Protec, AO Smith Product Preservers, etc, the system would have to be designed to the engineer's best guess of representative conditions. The closer any water heater is to that vendor's chosen set of reference conditions, the better the powered anode system will perform. I am sure that there is at least some level of protection offered to any system, which may in fact be a generally very high level indeed (or may not). Without seeing the durability experiment design to inspect how representative & comprehensive the conditions under test were; and without seeing the actual results; it is hard to say just how "universal" any such system might be.

Note that this information may in fact be openly available -- I simply have not looked. So to anyone taking the time to read this rather lengthy post, I am *not* implying that the Corro-Protec or any other system does not perform to its claimed level. I am just outlining the design challenges such a system faces.

 

[VincentV3]

I think it's great that you could see this technology in a field like this! It is certain that the more things to protect are big and complex (as in your case above), the more protection becomes complicated! In special cases like these, protection often needs to be adjusted in the process. This type of protection is used to protect boats, piles, water tanks and pipelines.

After what happened, I can fully understand your skepticism and respect your way of thinking. It is very rare that people take the time to learn as much in a specific area!

About the tests, the research and development period was spread over several years before having the final product meeting the different criteria. You can understand that I will not publish research and development results online on this forum, but here are the tests that have been successfully completed:
- Standard NACE SP0388-2007 (formerly RP0388-2001) of the NACE "National Association of Corrosion Engineer".
- Performance Evaluation of Corro-Protect Anodes
- Anode quality test
- Chemical composition
- X-ray test
- Aging test
- Accelerated life test of MMO ribbon anode coating

We would not recommend a product without being sure that it is safe and effective. We have new products in development that will revolutionize other sectors very soon!

Thank you for your interest in this technology

 

[LeBlanc]

VincentV3 and others, I'm curious:

We purchased and just received the 40-80 gallon Corro-Protec unit for our northern Michigan cottage where we have a private well and use a softener for our 50 gallon natural gas water heater. I'm to install it tonight, and we're anxious to lose the smelly odor from the hot water.

When we leave the cottage it's usually 3-4 weeks before we return. As such, we turn power off, open all faucets, and set the furnace to its lowest setting. I'm not certain how much water is actually removed from the tank when the faucets stop running (can anyone help me with this?).

While I understand no power to the unit means no anode is serving the water tank, I wish to verify two things:

* Will any harm to the unit occur if electrical power is applied and the titanium rod is not surrounded by water?

* If you know: assuming the Corro-Protec anode is not as long as the factory anode and does not extend into the actual water level inside the tank when faucets have drained, am I causing more harm to the tank at that point? Is there a way to verify whether the tank has enough water left in it to cover a portion of the Corro-Protec rod?

Thank you for your response.

This type of protection is used to protect boats, piles, water tanks and pipelines.

Corro-Protect Anodes
- Anode quality test
- Aging test

Thank you for your interest in this technology

 

[WorthFlorida]

If any faucet that is below the height of the water heater there is always a chance that the water level inside the tank will drop. You could add a shut off on the hot water pipe and when shutting down close both the cold and hot water valves at the water heater.

 

[Reach4]

When we leave the cottage it's usually 3-4 weeks before we return. As such, we turn power off, open all faucets, and set the furnace to its lowest setting

Are you opening the faucets in case of freezing? If you don't open the hot faucets, and close the cold into the WH, I would not expect the WH to drain. But even if you opened the hots, I still would not expect the WH to drain, because its output is on the top of the WH. Do close the cold input, however, in case your diptube does not have the usual small hole up top.

Will any harm to the unit occur if electrical power is applied and the titanium rod is not surrounded by water?

I am confident that the powered anode rod not being in the water would not harm the powered anode.

 

[LeBlanc]

Yes, I open all faucets to decrease the chance of freezing, but also so as to not have softened water in the lines for 3-4 weeks without activity.

Good to know that even if powered with no water covering it, the unit will not be harmed. Thank you.

Are you opening the faucets in case of freezing?

I am confident that the powered anode rod not being in the water would not harm the powered anode.

 

[LeBlanc]

Good idea, especially since ALL faucets are below the height of the WH. Thank you.

If any faucet that is below the height of the water heater there is always a chance that the water level inside the tank will drop. You could add a shut off on the hot water pipe and when shutting down close both the cold and hot water valves at the water heater.

 

[LeBlanc]

OK. I installed the Corro-Protec anode rod, replaced the drain valve, drained and flushed the tank, and we're pleased!

Our cottage water heater was manufactured in 2004, is served by a well and a softener, is turned off when we're not there, was drained last in 2009, and during 2018 the hot water began to smell. After trying many things, I came upon the Corro-Protec. While we've only used it for less than one day, we hope it is a long-term solution.

Everything went smoothly. Removing the original anode rod was easy, and while it did have a small amount of scale on it, it was completely intact and it smelled! Our 8' ceiling meant I had to saw it in half to remove it, but it was very little effort overall to remove and replace it. Since I had not charged the system upon arrival, I then decided to measure the water level with the faucets having been opened for a month. The water level was about 5" from the top of the tank, so that meant the replacement anode would be partially/mostly in water after draining the lines to faucets and bathrooms.

I then proceeded to drain the 50-gallon tank, and that took about an hour. There was no evidence of anything but clear water. I then replaced the plastic drain with brass, agitated the tank by opening the water valve briefly several times, stomping on the drain hose several times, and draining through both all of the faucets and the replacement brass drain valve (which drained much faster than the plastic valve). Water in both bathrooms was gray, and some evidence of sand was visible. I repeated the fill, agitate, drain process about 5 times and then had clear water with no sediment.

We heated the water, used it for a day (no odor), then when we left we turned power to the well off, opened all faucets,and left power to the Corro-Protec on. We look forward to the next visit to verify whether it worked. Wish us luck!

 

[KeithA]

Our stinky hot water is about 95% reduced since installing the anode (no problems on the cold water side). The main issue here is I still have well water with SRB (and IRB), so until I can treat the source, I can't eliminate the problem. About once every 2-3 weeks, I add a couple hundred milliliters of hydrogen peroxide to the hot water tank which kills the smell again. So it's a very minor inconvenience. I continue to look for an effective and cost efficient way to treat the water coming into the house in the first place.

Great discussion on the challenges of corrosion protection. I'm a metallurgical engineer by trade, so know too well the "what works here, doesn't work there" of both passive and impressed current cathodic protection systems.

 

[Reach4]

Our stinky hot water is about 95% reduced since installing the anode (no problems on the cold water side). The main issue here is I still have well water with SRB (and IRB), so until I can treat the source, I can't eliminate the problem.

You could try cranking the temperature setting up to make it harder on the SRB. Don't let anybody get burned.

 

[Bruce Garrison]

deleted

 

[Bruce Garrison]

We can discuss this on a better level now, I think. Looking at the Matcor offerings, as you linked to, you will note that they will use long anodes or even ring anodes to get the anodes closer to the target. While they can put an anode farther by use off a deep well, they try to keep the differences in distance from anode to protected areas not too different. Are you implying that the ACi Hybrid WH uses a stubby anode, and therefore stubby anodes are good?It seems to me that a stubby electrode at one end of a highboy WH leaves the other end significantly less protected. [bad link removed]

The only place the anode is needed is where there is an imperfection in the glass lining. If we were to assume the only flaw was at the bottom of the tank, a short anode could protect that. If we presume many little flaws distributed around the tank, the available current will be more at the areas closer to the anode.

View attachment 49846
In the above sketch, the red represents the positive anode. The green lines are trying to represent the available current density to protect various parts of the tank. A better drawing would have had the anode off-center, but that would be the case long or short. A useful graphic, I think, would be to represent the voltage at various points presuming a certain water conductivity such as might occur with 500 ppm of dissolved solids. That kind of graph is beyond me. It must exist on the web, I would think, but I don't find it.

I am not a pro, and I am not speaking as an authority.

I find http://www.dtic.mil/dtic/tr/fulltext/u2/a081707.pdf printed page numbers 10..13 showing water tank protective anodes for a water tank. The illustrations indicate that the range of protection is limited for a given anode. It is an old document, but they knew what they were doing back in 1979 too.

I know this is an old thread, but it comes up when searching for info about electric anode rods. I wanted to point out that the Air Force report (permalinked as the original link now requires some military subscription to access) Reach4 referenced earlier in post #20 does state in its conclusions on p. 28 that "Anode placement/location is not significantly important in reasonably well-coated water-storage tanks."