Distributed Computing Systems are a viable and less expensive alternative to parallel computers. However, a serious difficulty in concurrent programming of a distributed system is how to deal with scheduling and load balancing of such a system, which may consist of heterogeneous computers. Distributed scheduling schemes suitable for parallel loops with independent iterations on heterogeneous computer clusters have been proposed and analyzed in the past. This paper deals with the scalability of the centralized distributed loop scheduling schemes. We propose a hierarchical version and demonstrate that it is scalable. We compare the new version with an existing scalable scheme (Tree scheduling). We provide implementations in both MPI and CORBA.