Dehumidifiers having improved heat exchange blocks and associated methods of use and manufacture are disclosed. A heat exchange system in accordance with a particular embodiment can include a plurality of elements with a plurality of airflow channels. A plurality of peripheral spacers are positioned toward edges of neighboring elements and extend in a first direction. A first airflow path extends in the first direction, and is at least partially defined by the corresponding elements and the peripheral spacers. A second airflow path is defined by the airflow channels and extends in a second direction, and an airflow blocker is positioned at a corner portion of the elements to prevent fluid communication between the first and the second airflow paths at the elements. In certain embodiments, the heat exchange system can further include a dehumidifier having an evaporator positioned between the first and second airflow paths.