The E TES is designed to directly heat wet material, not the air. Use a IR thermometer to compare the material you are heating with the E TES to other material to determine how the E TES is working.
Other factors:
Temperature of the ambient air
Are you exhausting your moist air or using a dehu and recirculating the air back through the E TES
The more air (higher speed setting on your air mover) you are running over the heating coils the less of a temperature increase, use the least amount of air as possible to keep the air flow switch engaged for the most temperature increase.
Size of the room, try to contain the heat, either under a carpet or use plastic to keep the heat on the wet material.
The 240 volt E TES will put out more heat than the 120 volt