The top Therm-o-disc, #1 ( a simple on-off bimetal temperature switch, or thermostat) was secured to the unisulated interior metal tank with red RTV high temperature silocone (found in the auto section of hardware store) and is wired in series with a second identical Therm-o-disc (#2) that is secured with two tiny nuts, placed too close to the body of the disc to allow the application of even a tiny wrench or socket. Plan on an hour of turning the nuts one flat at a time with a tiny needle nose vise grip. Note: They will probably be corroded, and one of mine snapped off the tank. So what? Well ground (green wire)to the body of the Therm-o-disc and to the tank is supplied through that post, so don't break both of them if you have to remove. You can test all components right in place however with a continuity tester. There will probably be splices between the AC feed and the water heater wiring. Be sure power is off to unit, disconnect shore power and then cut out the the three splices, saving them, or disconnect at the junction box if installed. Be sure the water in the tank is cold or the tank is empty and attach your tester to the black & white wire coming from the tank. If you have a complete circuit, then the unit is OK. It's the wiring or in my case, one of the splices. I saved the splices as above and checked them and sure enough one of the splices was bad, one wire crimped into the splice was not stripped! I only discovered this after tearing all the other elements apart and testing separately. Alas! If you don't have continuity, remove the connecting wires from the Water Heater Element and use your continuity tester across the two screw connectors. No continuity here means burnt out element. You can get a new element at a plumbing supply or larger hardware store (Home Depot if you must). Removal of the old element is a royal PITA, as it is probably frozen in place and a good angle to get some muscle on it is impossible. DO NOT buy the cheapo ($5) tool
at the depot to remove the element, you need a real 1-1/2 inch socket with a 3/4" drive ratchet, with about a 18" handle. The cheapo tool was the basis of much frustration, banged knuckles, and itchy scratches on my arms from the semi-finished fiberglass edges of the opening. Go to a local rental place (Taylor Rental around here) and rent the giant socket & ratchet ($4 for an hour). Took the element out first pull, beautiful! Replace the burnt element with a similar wattage (1500W, $8.95), rewire and you should be all set.
If it's either of the therm-o-discs, they can also be replaced easily enough although I didn't source them as mine were fine. They work by simply pressing their temp sensitive parts against the outside of the metal tank, and open the circuit when the tank reaches temp. I assume there are two for a fail safe situation, so as to not boil the water in the tank if one failed when closed or the water level was not high enough.
Why in god's name Albin did not install this piece of equipment turned 90 degrees clockwise so all the important things faced out at you I'll never understand. I hope you never have to work on this shoddy little device, but I hope that if you do, this will help!
Me too. I run the water until it's empty, then pour 6 gallons into the holding tank. Open the hot water faucet until it runs pink. It's not the proper way, but I haven't lost a water heater yet. Now that I'm bragging, it will break.