Shape Transformation for Polygon Objects

An electrical heater to produce clean and dry compressed air comprising a housing in which an electrical heating means is centrally mounted and is surrounded by a coiled tubing to which compressed air is admitted at one end and exited therefrom at the other end, thence passed through a filter and led therefrom to a point of use. The filter serves to remove moisture from the compressed air and has replaceable elements which can easily be changed. A temperature responsive sensing element is provided adjacent the coiled tubing to control the degree of energization of the heating unit and thus the temperature of the compressed air.