Selgas
Only Steel glass lined mains pressure gas/electric cylinders have anodes fitted into them and they are usually mounted under the top lid cover and visable by an exposed hex nut – usually on the left hand side as you face the front of the cylinder. Sometimes the manufacturers fit a small disc cover over the access nut of the anode to “dress up” the otherwise untidy look of a cylinder.
The anode is not fitted on a cold or hot water line connection but screwed through the steelwork of the cylinder to enable it to accept any corrosion activity that may take place within the cylinder – hence it’s name a sacrifical anode that manufacturers claim should be replaced every 5 years or so with the same type and resistance as was originally fitted. Hope this helps. 
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians
