Horizontal multi-purpose composite atmospheric boiler

The present invention relates to a horizontal multi-functional composite normal-pressure boiler. Its primary boiler consists of base seat, arched water jacket, furnace chamber, concave convection pipe group, intake pipe, water header, discharging pipe, chimney and boiler body, and the secondary boiler is vertically placed behind the arched water jacket, and shares one base-seat, one chimney and one boiler body with primary boiler, and has itself furnace cavity, furnace door, slag hole, water jacket, smoke pipe, water tank and inlet and outlet pipes. The primary boiler and the secondary boiler can be combined or separated each from other to use, and each can be independently used. Its heat efficiency can be up tlo 85%, so that it is an ideal multi-purpose boiler.