A novel two-chamber design for thermal boilers is presented in this document. The boiler uses spiral-shaped tubes with conical and flat portions which form a combustion chamber. The use of a direct flame burner causes exhaust gas turbulence and increases the gas pressure in the main chamber. The high-pressure gases, which have lost their kinetic energy due to collision with spirals, leave the main chamber and enter into the secondary chamber, where their energy is used to preheat inlet water. The control of distance between spirals, the reverse flow of exhaust gases in the chambers, and the specific geometry of the spirals maximize boiler efficiency,

A novel two-chamber design for thermal boilers is presented in this document. The boiler uses spiral-shaped tubes with conical and flat portions which form a combustion chamber. The use of a direct flame burner causes exhaust gas turbulence and increases the gas pressure in the main chamber. The high-pressure gases, which have lost their kinetic energy due to collision with spirals, leave the main chamber and enter into the secondary chamber, where their energy is used to preheat inlet water. The control of distance between spirals, the reverse flow of exhaust gases in the chambers, and the specific geometry of the spirals maximize boiler efficiency,

A flash boiler has a water jacket and a vertically oriented interior passage which includes water tubes or superheating tubes, or both. The interior passage is a hyperboloid surface to induce draft. Water tubes and superheating tubes can be staggered so as to create a helical path for flue gas passing through the boiler. Water tubes and superheating tubes may include, internally or externally or both, heat transfer aids such as pins, fins or vanes, which may also be helices.

A flash boiler has a water jacket and a vertically oriented interior passage which includes water tubes or superheating tubes, or both. The interior passage is a hyperboloid surface to induce draft. Water tubes and superheating tubes can be staggered so as to create a helical path for flue gas passing through the boiler. Water tubes and superheating tubes may include, internally or externally or both, heat transfer aids such as pins, fins or vanes, which may also be helices.

A flash boiler has a water jacket and a vertically oriented interior passage which includes water tubes or superheating tubes, or both. The interior passage is a hyperboloid surface to induce draft. Water tubes and superheating tubes can be staggered so as to create a helical path for flue gas passing through the boiler. Water tubes and superheating tubes may include, internally or externally or both, heat transfer aids such as pins, fins or vanes, which may also be helicies.