Abstract: An apparatus accurately controls output water temperature of an instantaneous water heater to maintain a desired outlet temperature. A first electronic sensing device senses a flow of water through the heater, and an ignition sequence commences when flow has been detected. A second electronic sensing device senses an outlet water temperature of the heater, and a third electronic sensing device senses a midway water temperature of the heater. The burner output or outputs are controlled to maintain the desired outlet temperature, based on changes in water flow and incoming water temperature. With multiple burners, the burner outputs are staged to accurately control the output water temperature of the instantaneous water heater to maintain the desired outlet temperature.

Abstract: Apparatus is disclosed for detecting irregularities or flaws in seams such as the seams of cans. The apparatus includes means for irradiating the surface of the seam to produce reflected radiation signals, a plurality of radiation sensors, each having a selected field of view of the surface, and each producing sensor output signals dependent on reflected radiation signals received within such field of view. A signal processing means receives sensor output signals for a succession of fields of view along the longitudinal length of the seam and derives therefrom signal data representing a dimensional feature of the seam. Signl comparison means compares such derived data with signal data representing an acceptable dimensional limit and produces a rejection signal in the event that the dimensional feature does not fall within the limit. Means for classifying the nature of an irregularity is also disclosed, as is transport means for the movement of seams though the field of view of the sensors.