Electric Controls
Electric heaters heat up water with two horizontal elements running inside the tank of the water heater. One is located on the upper half of the heater, and one is located on the lower half. Elements are similar to the metal grill pieces found on top of household stoves. There are high watt and low watt elements. Low watt elements are better because they do not produce as much sediment, but they are more expensive. The lower element does more of the heating because it is wired to do so. Only one element works at a time. The upper element operates when a large amount of new cold water is introduced into the tank. Some tanks have only one element which will be located at the bottom of the tank. The top element has a high temperature shut-off switch which will turn off the element if the temperature reaches 190 degrees Farenheit. In single element tanks, this same feature is found. It comes with a red reset button similar to a GFI found on household electrical outlets. An adjustable thermostat is found on the lower element located on the outside of the tank. Thermostats are usually all set at 120 degrees Farenheit.
Gas Controls
Gas heaters have a thermostat which is directly placed in the water, and it is connected to the front control apparatus at the bottom of the water heater. A dial is found on the apparatus which has settings: ON, OFF, and PILOT. The knob located on the top of the dial apparatus has a recessed screw which controls the gas flame. If the temperature ever reaches 190 degrees inside the heater, the control itself will be shut down and cause the flame to die. A new control will have to be installed if this ever happens. On older heaters the control will shut off if the temperature reaches 210 degrees. Three tubes extend from the bottom of the dial apparatus. The largest tube, alwasy the middle tube, is the natural gas supply. The medium-sized tube, usually to the right, feeds gas to the pilot light switch so that the flame can initially be ignited. The smallest tube, usually to the left, is the thermocouple. The thermocouple gives power to the control after the pilot has been lit. If your pilot light ignites but will not stay lit, then the thermocouple needs replacement. The burner assembly is attached to the tubes and control and can be removed to clean. Do not take apart the control itself.