Caravan hot water system service or replacement
RV hot water systems incorporate a device designed to reduce corrosion on the internal metal components. A bar made of magnesium is installed in the base of the system, its correct name is a Sacrificial Anode...you will also find a sacrificial anode of the skeg of an out board boat motor. The idea is that the anode bar, which is easily replaced, will corrode thereby reducing corrosion within the water tank, or the outboard outboard motor. Anode bars should be inspected regularly, especially if water with a high concentration of minerals, ie, outback bore water has been used...six monthly inspections are recommended...
Warning...ensure mains power and mains water connections are disconnected from the RV before carrying out this maintenance work.
In this case the HWS is a US made Suburban brand, a very popular system used in the majority of Australian caravans and RV's...yours may be different but regardless it will still have a sacrificial anode installed somewhere...you may have to check your user manual or contact the manufacturer if you are unsure.
Before proceeding you will need to relieve the system water pressure, do this by pulling the drain lever towards you, obviously any water pumps need to be deactivated and there should be no hose connection to the RV...ensure also that you have shut down the 240v power connection. (you will be spraying water around this area during this operation)
The bar is installed behind a large hex head at the base on the lower left hand site, you will need a 27mm socket to remove it....it will also likely need an extension bar to get leverage.
A lot of water and gunk (magnesium sludge) will come out of the hole when the bar is removed, have something to capture it ready...allow it to drain completely...insert a hose so it goes to the back inside of the tank and flush, do this several times until the water comes out clean.
The bar at the top is new, the middle one 10 months old and the lower one about 12 months, the degree of wear will depend on the water quality and the use your system gets, in this case a mixture of Outback bore and town water had been used. When you re-install the bar ensure you apply thread tape, start it turning by hand, you really do not want to cross the thread here.
There bars can be worn right down but I feel I feel it is best replace them when about 70% worn due to the relatively cheap cost of these things and the damage your system will suffer if it is allowed to completely wear away.
(A new one weighs around 200 g so using a set of kitchen scales, at 140 g or so it is recommended to get rid of it)
I brought mine online, go for genuine Suburban units, they cost around $20 - $25..eBay.
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