70 ILCS 705/16.04a
The board of fire commissioners shall appoint all officers and members of the fire departments of the district, except the Chief of the fire department. The board of trustees shall appoint the Chief of the fire department, who shall serve at the pleasure of the board, and may enter into a multi-year contract not exceeding 3 years with the Chief.
If a member of the department is appointed Chief of the fire department prior to being eligible to retire on pension he shall be considered as on furlough from the rank he held immediately prior to his appointment as Chief. If he resigns as Chief or is discharged as Chief prior to attaining eligibility to retire on pension, he shall revert to and be established in such prior rank, and thereafter be entitled to all the benefits and emoluments of such prior rank, without regard as to whether a vacancy then exists in such rank. In such instances, the Chief shall be deemed to have continued to accrue seniority in the department during his period of service as Chief, or time in grade in his former rank to which he shall revert during his period of service as Chief, except solely for purposes of any layoff as provided in Section 16.13b hereafter.
All appointments to each department other than that of the lowest rank, however, shall be from the rank next below that to which the appointment is made, except that the Chief of the fire department may be appointed from among members of the fire department, regardless of rank.
The sole authority to issue certificates of appointment shall be vested in the board of fire commissioners and all certificates of appointments issued to any officer or member of the fire department shall be signed by the chairman and secretary respectively of the board of fire commissioners upon appointment of such officer or member of the fire department by action of the board of fire commissioners. After being selected from the register of eligibles to fill a vacancy in the affected department, each appointee shall be presented with his or her certificate of appointment on the day on which he or she is sworn in as a classified member of the affected department. Firefighters who were not issued a certificate of appointment when originally appointed shall be provided with a certificate within 10 days after making a written request to the chairperson of the board of fire commissioners.
To the extent that this Section or any other Section in this Act conflicts with Section 16.06b or 16.06c, then Section 16.06b or 16.06c shall control.
70 ILCS 705/16.04a