water heater with temperature control in the proportionalitu00e4ts area to pursue a better thermal efficiency

摘要

A water heater having a water tank and a electric resistance heating element (125) extending into the water tank for heating water in the tank. The water heater includes a proportional band temperature controller (100) for conducting electric power to the electric resistance heating element (125) in bursts. Each burst of electric power is followed by a period during which the temperature controller does not conduct power to the electric resistance heating element (125). In one embodiment, each burst of electrical power lasts for about 95 % or less of a cycle comprised of one burst of electric power followed by the period during which the temperature controller (100) does not conduct electric power.