To lower noise at the time of a self-priming operation and shorten self-priming required time by intermittently supplying water plural number of times in a state that a self-priming operation is temporarily stopped after priming is filled and a pump is started and normally maintaining the surface of the water high.
Because priming is replenished by supplying water one time or intermittently plural number of times (several seconds per one time) in a state that a self-priming operation is temporarily stopped after prescribed time elapses (10 seconds or more) after an electromagnetic water supplying valve cooperating with a microcomputer automatically opens and closes, priming is filled within a pump and the pump is started or priming is replenished intermittently plural number of times during the self-priming operation after priming is filled within the pump and the pump is started and a water level is maintained to a high level in an operating state in which inclusion water quantity is increased, air inclusion can be prevented. Thus, generation of noise caused by air inclusion and long time of self-priming required time can be prevented.
NAGANO YOSUKE
OTA GICHU
