Speaking of anode rods in water heaters...

Anyone have an idea about the length of an anode rod in an A O Smith Model FSG 40 propane gas water heater? My heater is 5 years old and I was just curious about the length in case I do decide to replace it. The tank is a 40 gal and is 53" tall (including the burner compartment underneath) and I only have a little more than 3 feet above the heater to be able to remove a rod straight out without having to undo sweated plumbing work to move or tilt the heater. Do they usually extend all the way to the bottom of the water tank, or are shorter? I checked at the A O Smith site and was able to find the PDF parts list for my specific heater, which document is in poor shape, with some parts of part numbers missing or unprinted in the document. Additionally, there are different anode rod numbers listed under headings like; SMR S44, SMR S33, SMR K32, SMR S4, etc. There is no SMR info printed on my heater label. No big deal at the present. I was just reminded of it because of an anode rod mentioned another thread.
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Articulated rods are available, so you don't have to worry about top clearance. Just saw them on This Old House within the last two weeks.
willshak wrote:

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On 12/8/2004 2:16 PM US(ET), Ray took fingers to keys, and typed the following:

Thanks. Yes, I know about articulated rods, but I am concerned about removing the old one first. I was asking is anyone knew the length of the one I have. If it is only 3 feet or so long, then there will be no plumbing, or even an articulated rod necessary. If it's longer, then it will require me to undo plumbing. Looking at the plumbing of the heater I have, I may just bite the bullet and unsweat the plumbing and replace the globe valves with ball valves. The globe valves were installed in 1986 and were last operated in 1999 when the heater was replaced. I always get a little anxious when operating a globe valve that hasn't been touched for years.

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if it's not good anymore, it will simply not be there as it will have dissolved over time. so the answer is: it will be of zero length. if it's not all gone, then it doesn't need replacement, or if you want to replace it anyway because it is partially gone, it will be really corroded and easy to break apart.

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I was also wondering why you couldn't just break up the old one as you remove it.
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On 12/8/2004 4:12 PM US(ET), Charles Spitzer took fingers to keys, and typed the following:

something.
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On Wed, 8 Dec 2004 14:12:19 -0700, "Charles Spitzer"

Well, there should always be the base steel rod with the sacrificial metals eaten away. If there is nothing left, consider replacing the tank as you've neglected replacing the rod waaaay too long and corrosion has already started in the tank.

Well, not necessarily. As the rod gets eaten, it's effectiveness becomes less and less. Once it's gone completely, you've already been eating the tank.
Again, you should never wait until the rod is completely gone since the steel inner shaft is not part of the sacrificial material.
In theory, if you replace the rod at optimal times, your tank should never rust out.
When pulling the old one up, you will have to cut it as you go (if clearance is an issue). You should wrap a rag around the rod at the opening and have a helper hold it at the rag with pliers while you cut sections. You don't want that baby dropping back in the tank or you'll have a much bigger job on your hands.
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I saw that episode too and was plesantly surprised! I will need to replace my rod probably around spring time and was wondering how I was going to do it. Now I know it will be a piece of cake!
The new rod is just in pieces and almost "hinged". When you take the old rod out, cut it as you go.

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willshak wrote:

You may find it's one heck of a job to bust it free. You'll probably have to find some way to keep the whole tank from rotating with the torque often required to "bust the rust".
Others have suggested applying penetrating oil a few days before you try and budge it, and someone remarked that standing a can full of ice cubes on the rod plug for a while to shrink it and crack the stuff holding it in can help.
Jeff
--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)
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willshak wrote:

I have an A O Smith Model FCG 40 natural gas water heater. It sounds like your tank has the same dimensions as mine.
Last month I replaced the magnesium anode rod. The old one, nearly down to its steel core, was right about 39 to 40 inches in total length. You should have ZERO problem removing your old rod (But see below.) -- it easily will bend enough for 36" overhead clearance.
I replaced mine with a 33" magnesium one that I got on eBay from an outfit (Inland Marketing -- eBay Id "inmain") in Calgary. They are still available, if you can't find one in stock on the A O Smith site.
The most challenging part of the job was loosening the old rod. I would HIGHLY recommend using a dose of "Liquid Wrench" and an impact wrench.
Good luck.
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Erma1ina wrote:

I forgot to mention that my water heater is a little over FOUR(4) years old. So you might consider checking your anode.
However, I DO use a water softener and keep the temp on "B" (approx. 140 degrees F); so perhaps my water is more aggressive than yours.
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On 12/8/2004 10:50 PM US(ET), Erma1ina took fingers to keys, and typed the following:

Just for kicks, I tried to close the supply valves to the heater, and wouldn't you know it, they wouldn't move. Perhaps it was a good thing, since it is 11 PM here. :-)
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Time for a ball-valve. California residential-commercial code requires a valve on the cold side.
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On 12/9/2004 9:32 AM US(ET), Leroy Mowry took fingers to keys, and typed the following:

They appear to be globe valves rather than gate valves due to the bulged sides. I mentioned in another thread that if I had to undo plumbing that I would replace them with ball valves, as I have done with every valve that I have had to replace or install so far.
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On 12/8/2004 10:41 PM US(ET), Erma1ina took fingers to keys, and typed the following:

I found that seller and item on Ebay. I see the gouge marks on the hex head of the old rod pictured there. Looks like they had to use a pair of lockgrip pliers on it, after they rounded off the head.
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willshak wrote:

I just looked at the eBay item again and noticed that the description states that the rod is ALUMINUM. The one I got was MAGNESIUM, as indicated by a little "bump" on the hex head.
I don't know if that makes a difference to you. Generally, the aluminum ones are priced lower than the magnesium ones but the eBay price of that anode is the same as it was for mine.
Maybe you can get a better deal on the A O Smith website.
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I recently replaced my 15-year old Rheem water heater. When it was 7 years old I tried to replace the anode, but couldn't hold the heater body from turning. Now, with it removed from the system and ready for the scrap heap, I tried more aggressively. I put my 1/2" drive breaker bar with a 3' pipe over it, on the anode. I inserted a 2x4 between the inlet and outlet nipples, then squeezed the two levers together. The anode rod came right out, with a loud crack. Don't think I'd recommend this for a connected water heater, as you're just as likely to break off the nipples!
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