See that hot water connection at the top of the picture above well I bet you did not know that there is an anode in there that has to be replaced periodically. It's a fact that most water heaters corrode from the inside out, the first indication is that something is amiss is a sulphurous smell each time that the hot water faucet is opened. Often this is put down to bad water in the fresh water tank and there are lots of remedies on the internet forums of how to deal with this from sanitizing the tank with all sorts of chemicals to replacing the hot water tank altogether. But often it is just the anode that needs replacing as if this is completely wasted the water inside the hot water tank starts to eat up the very fabric of the tank. The insides of most water heaters are aluminum and they have a coil that comes off the closed loop on the engine fresh water cooling circuit which heats the water indirectly as the engine is running. They also have an electric coil which can be switched on when the boat is plugged into shore power which works in a similar way to the electric water heater that you may have in your home. The anode which is made of magnesium protects the insides of the tank and heating coils. There is some miss information on the internet which states that these should be zinc. This is incorrect as zinc is close to aluminum on the galvanic scale and as such will not protect the internal parts. Magnesium is less noble that aluminum and offers much better protection and in any event if a replacement anode is ordered for a hot water tank the manufacturer will supply the correct part.
If the anode is not replaced the first indication that something is amiss is the sulphur smell mentioned above, then if nothing is done to address the problem the electric hot water fails soon after as it is consumed by the galvanic action. This usually gets the attention of the boat owner who then has the difficult task of either replacing the element or most likely the whole water heater.
Replacing the anode is fairly straight forward but the level of dificulty is directly proportional to how accesible the tank is. The first step is to isolate the water from the hot water tank. If you have a valve turn that off if not you may have to drain down the entire water system. Don't foregt too to turn off the electic element if this is on and watch for any water escaping from the water heater as it will be hot.
After turning off the water or draining it down lift the pressure release valve on the side of the heater to let built up pressure release.
Remove any hot water connections that are attached to the outlet on the tank. The boat I was working on had copper connections but alternatives may be flexible hoses or PEX type pipework. Irrespective of what you have they have to be disconnected.
With the pipes out of the way unscrew any nipples or elbows that are attached to the outlet. If they have been in place for a number of years you may need a fair bit of effort to remove these. With these removed the threaded part that actually goes into the tank will be visible. Push back white plastic trim cover to expose the non threaded part and get your pipe wrench on that and unscrew it. I guarantee that it will be tight.
No prizes for guessing which is the new anode. The old one was completely wasted away. I was working on a 12 gallon tank and just to give you some idea that new anode is 16 inches long!
Re installation is a reverse of the procedure outlined above but use teflon tape or pipe dope as appropriate to sea threads. Once everthing is back together check carefully for leaks before turning on the water heater and Ta dah fresh hot water without the smell, no chemicals required.
Incidentally the Seward 6 gallon water heaters do not have an anode but for less than $20 you can add one. You have to removed the drain stop tap on the front of the heater and replace it with a pencil anode that you can buy from online retailers. It's a modification that is well worth the effort as it will pro;ong the life of the heater by many years.
Comments