Forced flow air-cooled heat exchangers (ACHEs) as found in the petro-chemical, process and power industries use fans arranged in single or multiple fan rows to force air over finned tube bundles. Any flow disturbances or distortions experienced at the inlets of these fans tend to reduce the effectiveness of the ACHE. The reduction of the air flow rate through ACHE models having different numbers of fan rows is investigated experimentally. By varying the distance between the fan platform and the ground level, significant changes in air flow rate are observed and the results are correlated by an empirical relation which can be applied to the design of ACHEs. Fans along the edge of an ACHE are most affected by the distorted inlet air flow pattern. Furthermore, the influence of a walkway along the edge of the fan platform on the air flow rate through an ACHE is also investigated.