Ιt was a complex device which produced hot water for use with an ingenious control disposition of the consumed energy. It consisted of a cylindrical container with double walls inside of which coal burned that warmed the content of the container. Two perpendicular diaphragms separated the adjacent surface of the container into a large compartment (boiler), which constituted the hot water reservoir and a very small compartment (superboiler), which constituted the reservoir of the superheated water and steam. In the superboiler, a little above the bottom, a blind horizontal pipe went through the coals functioning as a heat accumulator of high output. Higher up, two inclined pipes (which went through the coals) connected the boiler to the superboiler and functioned as water feeders and steam producers. The reception of hot water (via tap which was found at the upper compartment of the container) came automatically with the simultaneous provision of cold water to the boiler (with a funnel-like orifice that led to its bottom so that there was no mixture of cold and hot water). The produced steam in the superboiler blew continuously (via a bent tube in the form of a zodiac) to the burning coals for the maintenance of combustion. The entry of new cold water into the boiler also caused rise of the level in the superboiler. Thus, because of compression, more steam was instantaneously ejected to the coals so as to manage the transient increased thermal needs of the boiler. In an improved variation of the boiler, Heron had added a triton who sounded a trumpet and a blackbird that sang with the help of the outgoing steam.