In each county in which this article is applicable there shall be a county board of plumbing examiners, consisting of three members, one of whom shall be the county health officer, who shall be ex officio a member and the chairman of the board. The second member of the board shall be a master plumber with not less than four years’ experience and the third member shall be a journeyman plumber with not less than four years’ experience. Such second and third members of the board shall be appointed by the governing body of the county, or a majority thereof. Each of such appointees shall hold office for the term of one year and until his successor is appointed as herein provided for. Any vacancy in the appointed membership of this board shall be filled for the unexpired term in the manner of the original appointment.