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How To Change A Water Heater Anode

Do it yourself plumbing information and education

How to replace your water heater's anode rod

Many people are unaware of just how much the water heater's anode rod does in order to protect the lining of your heater's tank. Inside every water heater is a long metal rod called an "Anode Rod" made of various metals. This rod protects the tank from corrosion by corroding first, before the tank. Once the anode is gone, the tank begins to corrode. To protect your water heater tank from corroding, this very important part of your heater may need to be replaced from time to time. Here we will show you how to replace your anode rod.

anode rodsDifferent types of anodes, and a corroded anode (right)

Please note that there are several different brands of water heaters that may require different or additional instructions. There are also many variables for removing and installing anode rods depending on how the heater is installed, access to the top or sides of the heater and different code requirements. We strongly recommend contacting the manufacturer of your water heater with any questions before beginning this project. Because of these variables, we are offering a very basic instruction on how to remove and replace an anode rod.

Items and Tools needed:

Step 1:
Locate the anode rod. Most will be located on top of the water heater, though some may have the anode located on the side. On most it will look like a hexagonal plug screwed into the heater. Some heaters have the anode attached to the hot water outlet nipple, to see what they look like click here. These will be connected to the pipe leading away from the heater. See the "Hot Water Outlet Anodes" section below for information on this type of anode.

Step 2:
Turn off the power supply to the heater. For an electric heater, turn off the circuit breaker for the heater. If the power to the electric water heater is left on, and air comes in contact with the heating element, the element can burn out. For a gas heater, turn the gas control valve to the lowest setting or the "vacation" setting. Do not turn it completely off to avoid having to light the pilot light again.

Step 3:
Turn off the COLD water supply to the heater.

Step 4:
Connect a regular garden hose to the drain valve at the bottom of your heater. Then lead the hose to a drain or outside the house. The hose must remain lower than the water level in the tank in order for the water to drain. When draining, the water will be hot, so be careful when handling the hose. Not much water will flow out of the drain until Step 5 is completed.
Note: If your anode rod is on the top of the heater, you will only need to allow the tank to drain about a quart or 1/2 a gallon of water. If the anode is located on the side, drain the tank until the water is below the anode rod port. Then close the outlet and remove the hose.

Water Reuse Tip: Drain water into a large container, then once the water is cooled it can be recycled and used to water a plant.

Step 5:
Find a faucet close to the heater that has a hot water supply and turn on the hot side. This relieves pressure in the tank by allowing air into the tank, which breaks the vacuum and allows the water heater to drain. If the tank is still under pressure when you try to loosen the anode, it just might fly out like a rocket!

Step 6:
Use a closed end wrench or socket wrench and ratchet or breaker bar on the hex head to remove the anode. Anode rods are usually installed and kept in the heater for several years, so it may be a bit hard to get loose. You can try using a "breaker bar" for better leverage or you can also try tightening the rod just a little to loosen up the threads. Also if your water heater is not strapped, to prevent moving the heater around - which could cause damage to the pipe connections - it is a good idea to have someone hold the heater while you try to loosen the anode.
DO NOT bang on the anode, the tank has a glass lining that could be damaged, allowing corrosion to start. DO NOT use any chemicals to try to loosen the threads, as they could get into the water heater contaminating the water.

Step 7:
Once the anode is loose, lift it out from the heater. Depending on how much clearance you have above the heater, you may need to bend the anode to remove it. Generally, there is not much left of the anode by the time it needs replacing since it is intended to corrode within the tank. If you find that the anode is hard to remove because it appears to be enlarged and cannot pull through the inlet hole, then there is still enough of the anode material to be working properly and it does not need to be replaced just yet. In this case you can simply screw the anode back in to the heater and replace it later.

Step 8:
Wrap the threads of the new anode rod with PTFE thread sealing tape, in a clockwise direction if holding the rod and looking at the threads or counter-clockwise if the rod is placed in a standing position and you are looking at the face of the nut. Only about five or six wraps around the threads are needed. Or use a quality thread sealing compound.

Step 9:
Insert the new anode rod. Most anode rods are completely straight and are difficult to bend. If your space is limited, you may consider using a flexible anode.

Step 10:
Tighten the new anode with your closed end wrench or socket wrench and ratchet. Again, to prevent the heater from moving and potentially damaging the pipe connections, have someone else hold onto the heater to keep it in place.

Step 11:
Open the cold water supply to the heater to refill the tank. Keep the faucet we mentioned earlier on, in the hot position.

Step 12:
The tank is full when water comes out of the faucet. Let the water flow from the faucet until all of the air is released from the tank. The faucet will usually spit some air out with the water until the air is expelled. The tank should be rid of any air when the water runs freely.

Step 13:
Check for any leaks in the connections on the heater.

Step 14:
Turn the power on for electric. For gas set the control back to the original temperature setting.

Hot Water Outlet Anodes

Some water heaters may have what is called a "Hot Water Outlet Anode" installed in the outlet side. These will usually need to be replaced at the same time as the regular anode. Since these will be connected to the outgoing plumbing the removal and installation is slightly different.

Most often, there will be a flexible connection from the hard plumbing to the anode's nipple. In this case, simply loosen the connection between the flex line and the nipple. You will then be able to remove and replace the anode as described in the above instructions.

In some rare instances, the hard plumbing may be connected directly to the anode's nipple. This may be a bit more difficult to replace as the rigid pipe would most likely need to be cut to free the anode. Then the pipe would need to be replaced. If this is the case we highly recommend hiring, or at least consulting with, a professional plumber before attempting to remove these.

Please note the information provided here is intended to give a basic knowledge of plumbing related repairs. This information is general, and may not suit all applications. If you are at all unsure of your abilities to complete one of these projects, please consult a professional. Always check with local code regulations and the proper authorities before beginning a project.

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