water heater anode is corroding

[acrwc10]

I was asked to look at a re-model today where, the water heater anode is corroding. The water service is copper and bonded correctly at the service with a #4 solid CU to the main panel. There is a ground rod at the main also bonded correctly, then the electrician went a step further and ran a bond wire from the main panel to the water heaters and jumped the Hot, Cold, and Gas pipes. All the neutrals and grounds are correct and only bonded at the main panel. So all the plumbing and electrical look good, and are installed correctly. There are two 50 gallon water heaters side by side, and the entire water system is copper. The anodes in both water heaters are degrading so fast(less then 3 months) that when the home owner fills the bath tub there is a residue in the tub after draining. These are new heaters and have magnesium anodes not the normal aluminum ones. When they are removed from the tank they look like they are 20 years old.
Has any one else run into this problem, and what did you find ?
P.S. the water quality in the area is good and no water softeners needed.

 

[Dennis Alwon]

If this is well water my bet is something in the water that is causing this. Are there other houses close with similar problems?

 

[acrwc10]

If this is well water my bet is something in the water that is causing this. Are there other houses close with similar problems?

No wells, city water (Cal. Water) and non of the neighbors have a known issue. I am of the mind set it is the anode being magnesium and maybe some salt or chlorination issue.

 

[Dennis Alwon]

Surely they wouldn't build a water heater that wouldn't work on a city water system...

Did you put an ampere meter around the gec to see if something is going on?

 

[acrwc10]

Surely they wouldn't build a water heater that wouldn't work on a city water system...

Did you put an ampere meter around the gec to see if something is going on?

Of course. there is a 0.03 to 0.04 amp reading on the water service, this is common in this area. I shut off the main power and checked again and there is no change in ampere readings. The heaters are bonded about 2' from the dielectric fittings.

 

[cadpoint]

Advise the HO to have there water tested and make sure it's tested with 24 hours, ask the tester before of their procedures. It's the water...

Draining the H2O heater and a flush and maybe even again, might get that built up sediment out of the tank. The real problem can be some of the flakes might be big enough to hinder the valve/ spicket, and its might have to be replaced, as well.

Remind them to turn of the circuit, if they want to play with the H2O heater.

If I ever play plumber I also rinse the line from the nearest outdoor spicket.

With the results of the water test, they could easy add a water filter on the house line and maybe even another at the H20 tank.

Bare that, the HO would need a Day Tank were they could pump from but would be odd and very expensive.

 

[Dennis Alwon]

I would do as Jude stated and change all elements and see what you get in 3 months.

 

[kwired]

Is there a DC current present? Electrolysis results from DC current flowing in one continuous direction. AC current because it reverses constantly does not present that type of problem.

Phone line could be a source of DC current.

 

[kwired]

No wells, city water (Cal. Water) and non of the neighbors have a known issue. I am of the mind set it is the anode being magnesium and maybe some salt or chlorination issue.

Advise the HO to have there water tested and make sure it's tested with 24 hours, ask the tester before of their procedures. It's the water...

Draining the H2O heater and a flush and maybe even again, might get that built up sediment out of the tank. The real problem can be some of the flakes might be big enough to hinder the valve/ spicket, and its might have to be replaced, as well.

Remind them to turn of the circuit, if they want to play with the H2O heater.

If I ever play plumber I also rinse the line from the nearest outdoor spicket.

With the results of the water test, they could easy add a water filter on the house line and maybe even another at the H20 tank.

Bare that, the HO would need a Day Tank were they could pump from but would be odd and very expensive.

If it is the water and they are on a city water system why don't the neighbors have same problem?

 

[acrwc10]

The anodes were changed, system flushed and all the expected service done. It was the plumber and the GC that called me to check the system out. They had the water heater manufacturers rep come out and they seem to think it is a grounding issue. The incoming water is clean on the cold side, coming out of the heaters it is not so clean.

 

[cadpoint]

Is there a DC current present? Electrolysis results from DC current flowing in one continuous direction. AC current because it reverses constantly does not present that type of problem.

Phone line could be a source of DC current.

That's interesting, now you'd need an addition power source, as your flipping breakers to test your theory?

One couldn't see it if they turned off the house power; I'm frankly thinking of those mobil hand set's, maybe even the router or various line(s) of equipment.

Point is you could only see it with a osciliscope and not a volt meter with it live, correct?

 

[acrwc10]

If it is the water and they are on a city water system why don't the neighbors have same problem?

One of the things that is different here is an average water heater has an Aluminum anode, the degrade slower. This particular model of water heater has only been out for 1 year.

 

[Jim W in Tampa]

So why not change to aluminum ? Flush tank out a few times and then see what happens. Perhaps its a chemical reaction to something they use in the water.

 

[acrwc10]

So why not change to aluminum ? Flush tank out a few times and then see what happens. Perhaps its a chemical reaction to something they use in the water.

I agree. This is most likely what is going on, and the best solution. I figured it would be a good idea to toss around here and see what came out of it.

 

[kwired]

The annode is put in the tank because it is intended to be sacrificed instead of the tank.

If aluminum annode degrades slower that may mean the tank degrades faster - I don't know for certain just a thought.

 

[acrwc10]

The annode is put in the tank because it is intended to be sacrificed instead of the tank.

If aluminum annode degrades slower that may mean the tank degrades faster - I don't know for certain just a thought.

True, but aluminum is what almost all water heaters use for the anode. If it is a chemical reaction to some water additive the anode is not going to save the tank.

 

[kwired]

True, but aluminum is what almost all water heaters use for the anode. If it is a chemical reaction to some water additive the anode is not going to save the tank.

And if there is a current accelerating the reaction it will still deteriorate rapidly and then the tank is no longer protected. You need to determine if there is a current involved in this or not and it does not have to be AC current.

 

[iwire]

I was asked to look at a re-model today where, the water heater anode is corroding.

I thought that was what a sacrificial anode was supposed to do?

 

[Split Bolt]

My bet is the water. Aren't sacrificial anodes made of zinc?

 

[Mgraw]

Aluminum, aluminum/zinc, or magnesium(best).