A mechanical draft cooling tower includes an air inlet and an air outlet. A liquid spray assembly is provided below the air outlet. A fill shell assembly is provided below the liquid spray assembly such that liquid can be sprayed onto the fill sheet assembly. An indirect heat exchange assembly is mounted beneath the fill sheet assembly. The indirect assembly usually comprises a series of coils through which a fluid to be cooled is circulated. A first air inlet is provided beneath the fill sheet assembly and includes a closing assembly. A second air inlet is provided beneath a top surface of the indirect assembly and includes a closing assembly.