Stand-alone storage heaters are a common type of domestic water heater in New England. They can be fired by gas, oil, or electricity. The tank has an aquastat which senses the temperature of the stored water and turns the heat source on and off as necessary. The tanks are usually made of steel, and contain a magnesium anode rod to slow the inevitable corrosion which must take place in the presence of water, oxygen and heat. Electric models have resistance elements which heat the water- a very inefficient and costly method. They do not produce combustion fumes, however, and have the advantage of not having the heat waste associated with having a flue. In contrast, stand alone gas and oil fired storage heaters lose heat through their flues. The same natural draft which takes combustion fumes into the chimney continues when the burner shuts off, pulling cool air through the central flue and taking the just-added heat back up the chimney and out into the atmosphere. Stand alone tanks also lose heat through their poorly insulated sides, and because they contain a large volume of water, they set up a gravity circulation in their piping, which moves hot water upward through the hot and cold water pipes connected to the tank. If uninsulated, the water pipes radiate the heat from the hot water into the environment, adding to the tank’s woeful stand-by loss record. One “benefit” of this gravity creep in the pipes is that the hot water is “closer” to the user when the tap is opened, causing less water to be wasted while the user waits for hot water to appear. Older stand alone gas fired models have the benefit of operating without need of electric power.