To adjust a clean-up temperature when an operating member moves forward to clean-up foreign material adhered to an inner surface of a discharging passage of a valve seat member.

An operating member 15 that can move forward or backward is arranged in a discharging passage 8 of a valve seat member 9. A bi-metal 14 is connected to the operating member 15. A case 13 is installed on the same axis as that of the valve seat member 9. The bi-metal 14 is stored in the case 13. A guide hole 13a for sliding and guiding the front side of the operating member 15 in an axial direction of the valve seat member 9 is arranged at one end of the case 13. An adjustment member 16 that can be operated to move forward or rearward in an axial direction of the case 13 is connected by a screw to the other end of the case 13. A guide hole 16a for sliding and guiding the rear side of the operating member 15 in an axial direction of the valve seat member 9 is arranged at the adjustment member 16. One end of the bi-metal 14 is fixed to the adjustment member 16 and the other end of the bi-metal 14 is fixed to the operating member 15. A manual operating member 18 that can be adjusted from outside to move forward or backward is arranged on the same axis as that of the operating member 15, the manual operating member 18 is moved forward to cause the operating member 15 to move forward.