water heater anode school

[Poindexter]

I finally got one out. We had been wanting to change the anode on our old water heater for years. The tank finally rusted through - because I didn't get the anode changed, and I have a new water heater going in. But I also had a test mule.

I have been reading up, mostly on internet forums like this one. In general new water heater anodes are driven in to near the max torque the fitting will take, and have a life expectancy of 6-24 months, depending on your local water. Once you get a new one broken out, get a thin layer of antisieze in the threads, then the pipe dope, and tighten it down as tight as you can get it with an 18" handle. Should be fine, and will be replaceable.

There remains the problem of getting the super tight from the factory one out. If you have it, you can try an impact driver or an impact wrench. Mostly likely the head is 17/16 inch, or 1 1/16 inches. 27mm is a bit loose, but potentially usable, you wont be putting it back in this hard. FWIW 27mm is 0.012" greater than 17/16, on paper. In practice, on both my old and new water heaters, my NAPA 17/16 socket was too small, my Kobalt brand (team blue) 17/16 socket was just right, and my Husky brand (team orange) 27mm impact socket was a hair loose.

I was really hoping to have a wife approved reason to bring in an impact tool, but I got both anodes out the old fashioned way. I used a thing named an Anita clamp, after my mom, who came up with the idea for changing tires on a boat trailer. Start with a 2x4. Drill two holes, near the middle, 12 inches apart, on the wide face. Stick eyebolts in there, use fender washers. Set the 2x4 on the ground, eyes up, lay the water heater or trailer tire in between the eyes. Grab a ratcheting tow strap, any color, hook into both eyes, wrap it over the top, and crank it down until something starts to complain. On a water heater, make some pencil marks where the top cover meets the side cover to make sure you don't twist the top case off. Using a half inch breaker bar and a 30" cheater pipe, total lever around 40-45 inches, stand on the 2x4 with the cheater bar on your shoulder and use your big muscles to get 'er done.

The vast majority - but not all - domestic hot water heaters use an anode with 3/4"NPT threads and a 17/16 hex head. 1 1/16 hex head, same thing. Replacement anodes are about $30 on amazon. Local, neither team orange, team blue or two plumbing supply places carry anodes at all. New water heater, electric, local, $500. Local, having a plumber replace the water heater I provide, $500. I can buy a LOT of $30 anodes for a grand. Life expectancy on anodes is 6-24 months, after that my tank starts rusting. I have a chore to do in November six months from now.

 

[EbS-P]

Thanks for this. I need some motivation to replace mine. 2 years old now. I wonder if the anode in a heatpump water heater will last longer? I’m tempted to pay to have mine replaced. Will definitely build the Anita clamp.

 

[peakbagger]

BTW anode life is directly dependent on your local water supply. Some water is agressive and they need to be changed out every couple of years, other water supplies are far less agressive and the anodes can last 10 plus years. The trick is to buy a spare and stash it somewhere near the heater, then check it in a couple of years.

Many heaters were installed without enough head room to remove a straight anode and replace it with another straight anode. In this case there are "hot dog" anodes that are a string of short anodes connected with a stainless cable. The old anode is cut with sawzall and then the hot dog anode just drops in.

Usually hitting a never replaced anode with a Map torch will do wonders getting it to unscrew.

While you are at it drain the sediment out of the bottom of the heater. The drain valves are usually not very beefy and leak eventually. They can be replaced with a good quality valve.

 

[Brian26]

Thanks for this. I need some motivation to replace mine. 2 years old now. I wonder if the anode in a heatpump water heater will last longer? I’m tempted to pay to have mine replaced. Will definitely build the Anita clamp.

The picture below was what my GE Geospring anode rode looked like after about 6 years. I replaced it in July 2019 and the tank was installed in 2013. I flushed the tank every spring and that spring I noticed some rusty sediment come out and changed it a few months later. My plan going forward is to just keep an eye on the spring flushes.

My 2nd generation Geospring has been rock solid running in heat pump only mode for over 9 years. This was one of the earliest hpwh when they first hit the market. Based off my electricity monitoring of it the compressor I estimated it has run over 15,000 hours to date.

The factory anode came right out for me using my 110 volt harbor freight electric impact gun. I went with the oem anode that I bought from Bradford White who bought the rights to the Geospring and still make it.

 

[semipro]

I've also seen where some have used torque multipliers to remove stubborn anodes.

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[bigealta]

The tank filled with water helps anchor it. you could use that strap and 2x4 with the tank in place, using your body as a stop while unscrewing with a big cheater bar. Now head room dictates your replacement choices. You can cut or bend the old anode when removing if necessary. Also if you are just short on headroom you can cut a straight anode rod a bit shorter. They are cheaper than the hot dog anodes.

 

[EbS-P]

Anyone have experience with the powered anode rods?

 

[bigealta]

Anyone have experience with the powered anode rods?

No but my electric water heater is over 20 years old. Think i replaced the anode once, but it was not even that bad at the time. Water varies quite a bit in different areas.

 

[peakbagger]

I used to work for a water utility long ago with incredibly pure water quality, hot water heaters didnt last long unless the anodes got changed out. They started adding something to the water to make it less corrosive as it leached the lead out of joints of domestic water supplies on older homes. The water was fine in the street but going through the house was sometimes enough to flag a lead issue. It was not that the water was acidic it just was so pure that is acted like it was acidic. Same issue happens with DI or RO water, its so pure it eats the pipes.
The water came out of Sebago Lake in southern Maine. They did zero treatment, no physical or chemical to the water until the surface water act came into existence, they put in an ozone system and then added some chlorine before it went into the transmission system to maintain some residual disinfection. Neat system, all gravity with 110 psi in Portland Harbor. They have standpipes around the communities that fill up by gravity at night and then reinforce the system pressure during the day.

 

[brenndatomu]

Neat system, all gravity with 110 psi in Portland Harbor. They have standpipes around the communities that fill up by gravity at night and then reinforce the system pressure during the day.

Why so high? Many plumbing fixture are only rated to 80 PSI, so 110 means having a regulator on every service.
Locally there was a new development that had a rash of toilets blowing up (fill valves failing) and it was found that they had 110 PSI, due to the elevation difference between this new neighborhood and the water tower...oops.

 

[peakbagger]

Its gravity system so unless they put big pressure reducing valves in system they live with what they got for pressure. Some utilities put turbines in the lines to generate power to reduced the pressure in the lines. Portland Maine got burned to the ground by the British and also had big fire that also burned most of the city in 1868 so the water system was built around having plenty of water. There is method of testing water supplies for the available minimum flow by opening up one hydrant and then checking the pressure drop at another hydrant. If the pipes in the area are undersized there will be considerable pressure difference between the static head and the residual flow pressure. We tested the fire flow at a big oil tank farm and only saw a 5 psi drop which meant plenty of water.

 

[Poindexter]

I have not fooled with powered anodes. Saw some for sale on Amazon, glad I don't have to figure those out.

As to differences in various water, I agree absolutely. You can (kinda sorta) see on my one at the top of this thread my old anode is caked with calcium. On many anodes, the zinc gets washed away leaving just the aluminum or magnesium rod in the tank. It depends.

Besides my anode local getting passivated by calcium deposition, I have one other data point. My new AO Smith brand water heater (home store team blue) is a 50 gallon model. The external case is 59.5 inches tall. The tank depth measured from the top with the anode out is 46 inches, and my factory installed anode rod is 32" total.

I ordered two of the folding or hot dog style from Amazon at 44 inch length. I have an 18" stand under the water heater, just enough to get a five gallon bucket under the drain - and defeat thermal bridging to the floor, and 35 inches of clearance up top to the ceiling. My garage ceiling is about 9 and a half feet. I went with the (37%) longer folding rods so I won't have to do the chore as often once I am familiar with the interval.

 

[semipro]

I've observed that some level of mineral content in the water (e.g., hardness) does protect the pipes from both corrosion and erosion. Of course, those same minerals can cause restrictions or blockages in the piping if the mineral concentrations are high.
Based on inspection of plumbing piping and fixtures in our house, our hardness seems to be at a level where it's high enough to protect our pipes without restricting them.
This applies to our water heaters also. We have one unit that's well over 30 years old now. Its twin was retired only because we went with a HPWH. I clean out the mineral sediment that accumulates in the bottom of the tank and check the anodes and replace as necessary (done once in 30 years).
This protection is one reason we have not installed a water softener.