Patent ID: 8869752

Claim:
A sectional boiler made of one of cast iron or aluminum, comprising: substantially annular sections including one front section, one rear section and at least one center section; wherein the sections together form a furnace chamber and satisfy the following conditions: the furnace chamber is substantially surrounded by heating gas passages and annular water compartments; the annular water compartments are connected to one another via hubs; the sections have one return connection piece, one feed connection piece, one flue spigot, and at least two anchor rods configured to hold the sections together; annular gaps are provided as heating gas passages between each two adjacent sections; the heating gas passages are subdivided into a primary portion and a secondary portion, the primary portion starting from the furnace chamber and extending approximately radially outwards and leading into a flue gas collection chamber on the outside of the sections, and at least one heating gas passage in the secondary portion extends radially inwards starting from the flue gas collection chamber to the flue spigot.