Skip to content
Anode Rod Compatibility
|Q:||I notice you sell anode rods. I’m wondering about compatibility with my water heater. First off, why don’t they sell these at hardware stores? They’re impossible to find. Now that I’ve found you sell them, are anode rods universal? How are they attached to the hex nut? I’d like to know all I can about what I’m getting myself into since this is a major undertaking for me. Thanks for the informative Web site!|
|A:||An anode rod is aluminum or magnesium cast around a steel core wire and hex head. For residential-type heaters, all anodes are the same diameter — 3/4-inch. If you have a 30-gallon or what they call a low-boy — a short, broad 40-gallon, you might have to shorten it. You shouldn’t put an aluminum rod together with a magnesium rod, or they’ll react and the mag rod will be gone in short order, defeating the purpose of installing it, which is to extend the life of the heater.|
Rheem always uses magnesium rods. For other makes, a mag rod will have a bump on top of the hex head. Hardware stores don’t sell anodes because there’s no market for them. There’s no market for them because nobody knows what they do. That’s one of the reasons this site exists: to inform folks. On the other hand, if you went to a marine supply store and asked for zincs, you would find another way anodes are used and one that is common knowledge to anyone who owns a boat. — Randy (1995-2000)
How Long Can a Water Heater Last?
|Q:||I just found out my water heater is about 18 years old. I don’t have any problems, but am wondering if they are just around the corner. Is there such a thing as a glass-lined water heater that doesn’t wear out? By the way, enjoyed your Web site & learned a lot. I may be trying some of your tips soon. Thanks.|
|A:||Sure there is — if you live in an area where the water is naturally soft — or, ironically, if you live in an area where the water is super hard. Sounds weird, doesn’t it? But in the first case, the sacrificial anode is consumed very slowly, and in the second, for some reason the anode plates over exposed steel areas with calcium carbonate. I have a 39-year-old tank in my living room (the one pictured on the home page, in fact) that came from the second-hardest region in the S.F. Bay Area. Naturally, in neither of these cases would the tank actually last forever, but 39 years is a mighty long time for a glass-lined tank to function. It didn’t rust out, either. I urged the building owner to replace it because it predated the code requirement for temperature/pressure relief valves and didn’t have one. Still, if you’re worried about it, look in Know-how on my Web site on how to inspect the combustion chamber and check for a rusty bottom. — Randy (1995-2000)|
Adding an Anode Rod
|Q:||First of all, thank you for all the detail about water heaters in language I can understand. I was prepared to buy a new water heater, and I discovered the anode is corroded by following your instructions. I have a U.S. Water Heater-made appliance, and it has a combination anode/hot water outlet. Do you have this for sale, or where would I find one? I’m not certain from your Internet order form if you have this kind. Your prompt response is appreciated, my anode is nearly corroded through.|
|A:||Yes, I sell them, however you might still be better off buying a new water heater. This is my rule of thumb for replacement: if there is still a little sacrificial metal all up and down the rod, putting in another one will give you significantly more life. But if it’s bare wire or worse, the new anode will be consumed in record time and you’ll either be stuck with replacing it often, or forget about it and have the tank fail. — Randy (1995-2000)|
Cleaning an Anode Rod
|Q:||I’ve had a gas water tank for 1 year and I’ve been checking the anode twice so far at 6 month interval. Both time I found the rod to be a little over half its normal size which actually came as a surprise the second time since it barely changed. There was also some deposit stuff on it and decided to clean it before I put it back each time. Could you please tell me what is that deposit and is it a good idea to clean the rod before I put it back? Thanks. PS Love your site.|
|A:||It sounds as if you have an aluminum anode. They do sort of expand when they start to corrode. You don’t need to clean it. The gunk on it is just normal corrosion. On the other hand, you might consider replacing it with magnesium, since aluminum adds a lot to sediment buildup, among other things. Why are you checking so frequently? Do you soften your water? — Randy|
|Q1:||The company says it’s aluminum but the supplier says it magnesium. Is there a way to tell? I’m checking it because I don’t have a clue when I’ll have to change it and since it was close to ½ it’s size after 6 months I thought after a year it would be about time to replace it. How long should it last? No we don’t have water softener. What do you mean by sediment buildup, among other things? If the gunk is just normal corrosion, does it help the rod do its job?|
|A1:||Well, first, I apologize: I misread your post and thought the anode was a little larger when you pulled it out, not smaller. It was late at night….. I suggest you read the sections on anodes and sediment under Common Issues from the home page. That will answer your questions about those issues and teach you how to tell aluminum from magnesium. It’s unusual for an anode to be consumed so rapidly when softening isn’t being used. Whatever deposits there are, though, are just part of the corrosion process. People are always shocked to see partly consumed anodes and often think there’s something dreadfully wrong. — Randy|
|Q2:||This site really has some good information. Turns out that the gunk I’ve been cleaning on the rod is without a doubt calcium carbonate. The rod’s hex head is definitely flat making it aluminum but it doesn’t say that aluminum rod will add sediment to the tank but I will take your word for it. I’ll be replacing the rod with one I bought already. The receipt says it is magnesium but it’s not like in the picture showed under Anodes, the bump is not rounded but looks more like the core wire is cut square and protruding just slightly from a aluminum rod’s hex head. It’s like a combination of both picture if you see what I mean. Would it be magnesium? If only I could add a picture!! (2/08/05)|
How Does a “Combo” Anode Work?
|Q:||The subject says it. I want to learn about the operating principal of the combo anode rod which appears to be electrically insulated from the tank shell by it’s plastic hanger. My limited understanding about the electrochemistry of sacrificial anodes is that they must be electrically connected to the metal they are protecting, i.e. the tank shell. Thanks guys.|
|A:||If you had X-ray vision, you would see that there is a sleeve of steel underneath the plastic that extends down to one half inch from the bottom, which has a hole in it. The anode slips into that hole and makes the necessary physical connection. — Randy|
|Q1:||I hear you Randy, but I’m having some difficulty understanding where that steel sleeve you describe makes electrical contact with the steel of the nipple. A little more detail would help me understand.|
|A1:||A different approach to answering the question is … If you took an ohm meter and checked continuity between the pipe nipple and the anode rod itself, you would find they are connected. When the nipple is screwed into the tank, it is connected electrically to the steel of the tank. So, the anode is connected to the tank through the nipple. The test with the meter and the fact that the sacrificial metal “goes away” both help to prove it works! Should you remove one to replace, get out your hack saw or grinder and you can see just how that connection is made. It is as Randy described. Hope that helps. — Larry (2/06/05)|
Difficulty Removing Anodes
|Q:||I recently had a new water heater installed from Home Depot. It’s the GE Smart Water gas heater w/ a 12 year warranty. About 3 weeks after it was installed the hot water developed a STRONG sulfur smell (we are on a private well w/ a water softener). After lengthy research on this site and others, I am sure this is due to the magnesium anode rod and that I need to replace it w/ an aluminum/zinc alloy rod.|
Knowing all this, my questions are as follows: 1) Does this model contain multiple anodes? I see one hex bolt head on the top of the heater, but I have read posts that lead me to believe the 12 year model may have a second anode hiding somewhere. If so, how do I replace it? 2) The hex head for the anode rod is sitting about 4 inches below some copper water pipes. There is enough room to get a socket onto the head, but I don’t know if I will be able to angle the anode to remove it from the tank.
I am trying to decide if I want to tackle this myself, or if I should order a new rod (rods???) and call a plumber to perform the installation. I am somewhat comfortable unscrewing the inlet/outlet nipples from the tank to possibly rotate the tank so the rod can come out, however I worry that the gas pipe might be affected. I am not as comfortable working with gas piping. Thanks in advance for any replies!
|A:||There is a strong likelihood that there is a second anode rod screwed into the hot-water port. The acid test is to disconnect the plumbing and run a long screwdriver down the nipple. If it stops after a couple of inches, it’s found the anode. As to the rest, it’s really a judgment call. You might have trouble removing the anodes, too. Sometimes they’re very tight.|
On the other hand, the tank is new, so it might not be a problem at all. Before you buy anything or do anything, though, find out what level of softening is being used. Oversoftening will make the problem worse. Generally, you want to soften to about 100 ppm hardness. You don’t want to soften to zero. Adjusting that might alleviate the problem. If not, buy one hex aluminum/zinc rod and one combo rod. — Randy (1/17/05)
To Fix or Replace?
|Q:||So, I tried to get my water heater replaced with a new one, but the plumber said it would be an extra $375 to bring it up to code (the vent isn’t right, it has no drip pan, no drain, and it’s in a closet above the dryer suspended 5 ft off the ground–he has to get up in the attic to work on the top of it). So I asked about fixing my old one, which won’t stay lit and leaks from the drain (about a gallon per day).|
This water heater is old. It’s a Ruud 30 gallon (the largest that will fit in that tiny closet), and if I’m reading the serial number right, it was made in 1988. He tried replacing the thermal couple and said that it was the “body valve”, and it would be about $175 to fix. It would take me a few months to save the money to get it up to code so he can replace it with the new one, or I could get the one I have now fixed.
So, my question is, would it be worth spending a couple months re-lighting it every twenty minutes and emptying the little tupperware container I have catching the leaking water every couple hours, or is it conceivable that this water heater would work for a few more years if I get it fixed? The combustion chamber doesn’t seem to have much corrosion at all, but I have not tried to drain it in the two years I’ve had this house, so I’m not certain about sediment or what’s going on inside the tank.
|A:||First, the dripping drain valve is a simple fix. You just replace it with a ball valve. As to whether the tank is worth servicing, it all depends. If the combustion chamber is OK, the next step would be to check the anode. If you can get it out and it’s still got some sacrificial metal on most of the length of the core wire, there’s a good chance that a new rod, or maybe even two, will keep the tank going for a long time to come.|
You have one advantage here: it’s only a 30-gallon tank. Thirties and 20s tend to last longer that 40s and bigger because the anode is the same size in all of them, but the interior surface area it is protecting is smaller. You’ll have to weigh the cost and trouble of one thing against the cost and trouble of the other. Hope that helps. — Randy (1/07/05)