Method for detecting air in instantaneous water heater analyses saw-tooth flow characteristic indicative of presence of air in water to determine freedom from air

摘要

After the instant (t0) when the tap is turned on the heater is not energised until the water flow has reached a set level. Subsequently rapid fluctuations in the flow meter propeller, due to the presence of air, induces a saw-tooth flow characteristic. During a period (Ts), which corresponds to the time the heater could be safely energised with zero flow, a microprocessor analyses the resultant wave shape to determine whether the difference between the maximum and minimum wave shape peaks indicates freedom from air and continued use is safe.