The Suburban Hot Water Anode in your caravan is a replaceable item. I will show you how to inspect and replace step by step. It’s an easy thing to do and it has to be done regularly.
What Is The Anode For Anyway?
The anode in the hot water heater in your caravan is actually meant to corrode away over time. Anodes are made from magnesium and they protect steel by a sacrificial electrochemical action. Magnesium is electro-negative relative to steel. When a magnesium rod is fitted to a steel tank filled with fresh water, a current will constantly flow through the water between the rod and any exposed steel area on the tank wall. The circuit is completed through the tank back to the magnesium rod. This protective current is produced by the magnesium releasing ions and this results in corrosion in the anodic area. A magnesium (the anode) corrodes instead of the steel tank (the cathode). This principle of electrolytic corrosion control is called cathodic protection. Because cathodic surfaces cannot rust, the steel tank is protected.
So now that we know a bit about anodes, let’s replace one. I generally check the anode every six months or so. It won’t usually need replacing this often, but it’s easy to check so I do.
Step 1 – Tools & Replacement Anode
The photo below shows all of the bits and pieces you will need to do the job. You don’t necessarily need the tank rinser, a hose with a decent nozzle will do an ok job but I reckon the rinser gets in to the corners and top front of the tank better. Same with the multi-fit tube spanner, if you have the correct size socket (11/16″) you can use that instead. Replacement anodes, the rinser and removal tool can all be bought online from any of the caravan spares places or sourced from any caravan shop.
Items Needed To Replace Suburban Hot Water Heater Anode
Step 2 – Disconnect Water & Open A Hot Water Tap
Before you get started you need to do a few things. Make sure your van isn’t connected to mains water, turn off your water pump and open the hot water tap to relieve any pressure in the system. If you haven’t got a pump isolater switch then just disconnect the 12v system.
Step 3 – Open The Cover To Your Suburban Hot Water Heater
Next you want to open the cover that protects your hot water heater. They’re pretty much all the same. Pull on the little toggle then turn it until it lines up with the slot and then simply lower the flap.
Replacing A Suburban Hot Water Anode Open The Cover
Step 4 – Place A Bucket To Catch The Water That Will Drain From Your Tank
A couple of tips. Make sure the water in the tank is cold as it is going to all run out. Put a bucket underneath it, about 50% of the water will go in to the bucket, the rest will just go everywhere. It’s a good idea to do it in your driveway rather than inside of your garage.
Step 5 – Remove The Anode
With the cover open you should be able to see the end of the anode. It will be down towards the bottom of the unit. Fit the multi-fit tube spanner and put a screwdriver or something similar through the holes in the tool to give you a bit of leverage. Turn the tool counter-clockwise and the anode will unscrew.
Closeup Of Anode And Removal Tool
Step 6 – Inspect Removed Anode & Determine If It Needs Replacement
Once you have removed the anode have a good look at it. If it’s in pretty good condition like mine was it’s perfectly ok to re-use it. I replace mine if they are more than about 50% gone. The life you get out of them depends a bit on the quality of the water you have been using. If you are mostly using city tap water then they seem to last for well over 12 months. If you are using bore water from out bush they can be gone inside of three months. If you are using poor quality water it pays to check your anode more often.
Note the new anode is longer than the old one in the photo below. The replacement is a multi fit one – not specific to the 20 litre Suburban hot water heater. It fits fine, you just need to trim about 3cm off the end of it with a hacksaw before installing.
Old And New Anodes For Comparison
Step 7 – Rinse The Tank Out
Now you need to rinse all of the old bits and pieces of anode out of the tank. I use a rinsing tool as I find it does a better job than just a hose nozzle. That being said I used the hose nozzle for ages before buying the rinser thing. Work it in and out and turn it around to get up in the corners both front and back and top and bottom. Keep on going until the water runs perfectly clear. When the water is running clear squirt a bit of water around to clean up the bottom of the tank recess and also the tank cover. Wash down the side of your van while you are at it.
Rinsing Out The Tank With Rinsing Tool
Step 8 – Thread Tape
Before refitting the old anode you need to remove the old thread tape. I just use a small screwdriver to lift it then unwind it with my fingers. Do this on the anode and also inside the thread on the tank. Remove as much of the old tape as you can without spending all day on it. After removing the old tape put on some fresh tape. About three or four winds around will be ample. Usually new anodes will come with tape already on them.
Remove Old Thread Tape And Replace With New
Step 9 – Install Suburban Hot Water Anode & Turn The Water Back On
Now you just need to insert the anode and using the multi-fit tube spanner tighten it up. Just nip it up tight, there’s no need to go overboard with the amount of torque you apply to it. After that you can close the cover. Turn off any taps that you have opened to relieve pressure in the tank and turn your water pump back on. You will hear the tank refilling. Wait until your tank has completely filled before turning the heater on to test.
