Abstract: A method of controlling a gas-fired water heater. A resistance input is received from a sensor configured to sense flammable vapor near the heater tank. The resistance input is compared to one or more previously received inputs from the sensor. Based on the comparing, one or more functions of the heater are controlled. This control method can be used to compensate for gradual ageing of the sensor.

Abstract: A gas-powered water heater includes means for stepping down a line voltage from a receptacle remote from the tank, means for using the stepped down voltage to provide a low voltage, and means for using the low voltage to sense conditions pertaining to the heater and to control heater operation based on the sensed conditions. Using a plug-in transformer to provide power for microprocessor control makes it unnecessary to install a line voltage line to the heater.

Abstract: A relay has a leaf spring that is secured to a planar seating section of a yoke leg and/or to the planar seating section of the armature and has an unsecured spring section extending beyond the free end of the yoke leg or, respectively, the armature. In order to avoid a plastic deformation of the leaf spring given impacts, the planar seating section respectively merges into a convexly curved roll-off section of which the leaf spring rolls off given a blow without being bent permanently. The end of the roll-off motion is expediently limited by a detent and, in this way, it is assured that the relay does not suffer any permanent modifications of its characteristics, even given heavy blows.