Weak-heapsort uses one more bit for each element in the heap that is not in-place. In this work, we propose the use of multiple heaps in the heapsort algorithm, in order to decrease the height of the required trees (and hence the time for their manipulation), thus achieving better performance. To retain the in-place property in our variant, we perform a kind of multiplexing so that different heaps are organized in the same array without using any auxiliary space. We also present a theoretical analysis of our algorithm, providing a specific formula for computing the optimal number of heaps to be used, and back up our theoretical findings with an experimental study, which shows the superiority of our approach with respect to the classical HEAPSORT.