Water heaters of all sorts and sizes last longer if protected from corrosion, including rust. An anode rod is a section of sacrificial metal, often made of magnesium, suspended within the storage tank. It “dissolves away” but by doing so, helps to prevent rust on other, more important parts. Replacing the anode perhaps every 3 years will undoubtedly prolong the life of the heater. I’m guilty of letting a small on-demand under-sink heater go a bit too long without replacing the internal anode rod. I may showcase the replacement of the anode on a large water heater another time.
Here’s the water heater I have. I was suspicious the anode needed to be replaced because I had to keep turning the temperature dial higher to get the water hot enough to suit, plus the pressure relief valve seemed to be popping a bit more than it should.
A small heater like this is best serviced by removal so that it can be emptied, cleaned, and flushed. The water feed to the heater needs to be shut off prior to any work, as well as the electric supply line if the heater is powered that way. In the picture above, it’s already been disconnected from the incoming and outgoing water lines and unplugged from its power outlet. Note the two copper “unions” on the stubs protruding from the top of the tank. Those make removal and installation a breeze, and those processes can usually be done many times before the union begins to leak and needs to be replaced.
The procedure for anode replacement is rather a simple one of removal, cleaning, replacement, and installation. Here’s how this particular heater came apart:
There is a small temperature sensing unit which is part of the thermostat and just gets pulled out of its housing. The unit electrical connections need to be slipped off:
All of the above exposes the real “meat” of the heater – the element itself. It’s usually held in place with a group of screws or bolts/nuts, and is pressed against a rubber gasket to seal the water in. (By the way, if you see that the rubber gasket is worn badly, has leaked, or is in some other way damaged, it needs to be replaced, or water WILL find its way out from the tank.) In this heater, there were four nuts to remove to allow the element to be extricated:
The element was extremely crusty with “hard water” deposits, and the old anode rod was nearly completely dissolved away!
The crustiness needs to be removed, and a combination of a vinegar bath, manual scraping with a knife and wire brush, and a buff on my grinder (with a brass wire wheel) did the trick.
The replacement anode had a small threaded shaft extending from the top, and was directly screwed back in place once the crustiness was removed.
Looking down into the tank, I could see remnants of other hard water/lime deposits, so I dumped out the tank. This came out immediately:
…and this pile came out after flushing the tank under pressure using a garden hose:
With the tank clean, it was just a matter of reversing the above steps and assembling things. If you’re completing a similar project, be sure to let the tank fill with water prior to plugging it in and turning it on. It’s also critical to remove any faucet-end screen and let hot water flow/flush for a minute or two before replacing it, because there could still be particulates that may now be in the system.
I hope all your projects go well. Thanks for reading, and happy restoring!
Ed
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