While we were travelling around Australia, we ran into Bucko and Janet quite a few times. Bucko mentioned to Rob that it was a good idea to change the hot water system anode from time to time, and showed him how to do it.
This week we performed this essential bit of maintenance on our van. Here are a few pics to show you the difference between the old anode and the new, and some links to online videos that demonstrate the technique. We have the Suburban brand hot water heater, which is the most common type in use; however there are different brands out there that do not have an anode, so best check your water heater brand before going in with all spanners & tools blazing.
(Oh, and at this point we need to issue a disclaimer: we chose to do this ourselves after being shown how with our caravan, but if you’re at all unsure, get a qualified tradesperson to do it.)
You might – as we did – get a bit of a shock at the way the anode looks when you pull it out; it doesn’t look anything like the new one! This is because the job of the anode is to protect the inside of the hot water service. It does this by ‘sacrificing’ itself, which is why it looks like it has been gnawed by a rat.
- Make sure electricity or gas feed to hot water system are turned off
- Make sure water supply to van is turned off.
- Take care with hot water spilling out if you have not allowed water to cool first.
- Use a search engine and type in something like: “replacing an anode in a caravan water heater” and you’ll find detailed instructions on websites and and videos on YouTube.
- Check the size of the anode – they come in different lengths.
- Before turning back on the electricity or gas supply, ensure the water heater is refilled.
Beware of Imitation Suburban Anode Rods
When the time comes to replace the anode rod in your Suburban HWS please take note of the type of thread on the rod. Genuine Suburban anode rods are NPT National Pipe Thread. Be aware that whilst it may seem that BSP British Standard Thread anode rods (Commonly seen in Australian market place to suit household domestic unit) will fit, they will cause damage to the fitting on the tanks they require some force to install tightly. NPT and BSP threads are not compatible with each other – the thread pitch is at different angles. Using a BSP anode rod inside a Suburban HWS will cause the seal to be ineffective by smoothing out the pitch in the female NPT. The result could be costly. So please make sure it is a genuine Suburban Anode you replace next time.
Good heads-up Wayne… we were careful to order a Suburban brand anode; but it is somewhere that people could easily be caught. Your advice just might save someone from making a purchase that they would regret!
NPT is the acronym for an American type of thread used in Piping systems. N and P stand for National Pipe, the T stands for TAPER, not Thread!
On the Suburban water heater, and many other plumbed products, the NPT threaded plug (in this case with an anode attached to it) is screwed into an NPP socket, NPP means National Pipe Parallel.
The action of screwing the tapered thread into the parallel thread provides a positive locking, as the outside diameter of the tapered plug increases as it is wound into the parallel socket, eventually the sizes match and the plug locks in. Additional use of a sealant compound is advisable as the threads will ‘lock up’, but rarely seal, especially in pressure applications.
BSPT and BSPP (or in some cases known as BSPG) British Standard Pipe Taper and Parallel, are the preferred thread forms in most other countries (the Americans always have to do it differently) and the two, NP and BSP are not compatible with each other. For example a 1″ BSP thread has 11 threads per inch of thread length, NPT has 11.5 threads per inch, so initially they will screw together, but persisting in tightening them will damage or destroy the threads!
So, for a Suburban RV Hot Water Heater, Always ensure that you by an Anode with an NPT thread.