A valve assembly comprising: a shaft, the shaft comprising; a sight through-hole; and a flow through-hole; the valve assembly further comprising a shaft position mechanism, the shaft position mechanism comprising; a driving means configured to provide movement to the shaft; at least one emitter (23, 25) and at least one corresponding sensor (22, 24); the valve assembly further comprising at least one flow path from at least one fluid inlet to at least one fluid outlet (42, 43); wherein the shaft is configured to move across the at least one flow path so as to allow flow therethrough in a first position, and to block the at least one flow path in a second position; wherein the at least one emitter (23, 25) and the at least one corresponding sensor (22, 24) are positioned such that, when the shaft is in the first position, the sensor (22, 24) can sense the emitter (23, 25) through the sight through-hole of the shaft, and when the shaft is in the second position, the sensor (22, 24) is blocked from the emitter (23, 25) by the shaft; wherein the at least one emitter comprises a first and a second emitter (23, 25), and the at least one corresponding sensor comprises corresponding first and second sensors (22, 24), and characterized in that the at least one fluid outlet comprises a first and a second fluid outlet (42, 43); wherein the shaft is further configured to move to a third position so as to allow flow from the at least one inlet to the first outlet, and block flow from the at least one inlet to the second outlet; and wherein the first and second emitter (23, 25) and the corresponding first and second sensors (22, 24) are positioned such that; when the shaft is in the first position, the first sensor can sense the first emitter through the sight through-hole of the shaft, and the second sensor is blocked from the second emitter by the shaft; and when the shaft is in the second position, the first and second sensors (22, 24) are blocked from the first and second emitter (23, 25) by the shaft; and when the shaft is in the third position, the second sensor can sense the second emitter through the sight through-hole of the shaft, and the first sensor is blocked from the first emitter by the shaft. a sight through-hole; and a flow through-hole; the valve assembly further comprising a shaft position mechanism, the shaft position mechanism comprising; a driving means configured to provide movement to the shaft; at least one emitter (23, 25) and at least one corresponding sensor (22, 24); a driving means configured to provide movement to the shaft; at least one emitter (23, 25) and at least one corresponding sensor (22, 24); the valve assembly further comprising at least one flow path from at least one fluid inlet to at least one fluid outlet (42, 43); wherein the shaft is configured to move across the at least one flow path so as to allow flow therethrough in a first position, and to block the at least one flow path in a second position; wherein the at least one emitter (23, 25) and the at least one corresponding sensor (22, 24) are positioned such that, when the shaft is in the first position, the sensor (22, 24) can sense the emitter (23, 25) through the sight through-hole of the shaft, and when the shaft is in the second position, the sensor (22, 24) is blocked from the emitter (23, 25) by the shaft; wherein the at least one emitter comprises a first and a second emitter (23, 25), and the at least one corresponding sensor comprises corresponding first and second sensors (22, 24), and characterized in that the at least one fluid outlet comprises a first and a second fluid outlet (42, 43); wherein the shaft is further configured to move to a third position so as to allow flow from the at least one inlet to the first outlet, and block flow from the at least one inlet to the second outlet; and wherein the first and second emitter (23, 25) and the corresponding first and second sensors (22, 24) are positioned such that; when the shaft is in the first position, the first sensor can sense the first emitter through the sight through-hole of the shaft, and the second sensor is blocked from the second emitter by the shaft; and when the shaft is in the second position, the first and second sensors (22, 24) are blocked from the first and second emitter (23, 25) by the shaft; and when the shaft is in the third position, the second sensor can sense the second emitter through the sight through-hole of the shaft, and the first sensor is blocked from the first emitter by the shaft. when the shaft is in the first position, the first sensor can sense the first emitter through the sight through-hole of the shaft, and the second sensor is blocked from the second emitter by the shaft; and when the shaft is in the second position, the first and second sensors (22, 24) are blocked from the first and second emitter (23, 25) by the shaft; and when the shaft is in the third position, the second sensor can sense the second emitter through the sight through-hole of the shaft, and the first sensor is blocked from the first emitter by the shaft.