The utility model discloses a novel hot air boiler comprising a top housing (1) of a boiler body, a chimney (7) and a flue duct collection box (5), wherein the chimney (7) is arranged at the upper part of the flue duct collection box (5) and is communicated with the flue duct collection box (5); a ventilation opening (6) is formed on the top housing (1); an air door arranged at the ventilation opening (6) is a hinged cover plate (8); the cover plate (8) is arranged below the ventilation opening (6); and a stop block (10) is arranged at the hinged part. By adopting the novel hot air boiler, air passes the ventilation opening, so that on one hand, heat quantity in the boiler body can be quickly taken away to quickly lower the temperature of the boiler body, and on the other hand, indoor temperature can be kept to some extent, so that residual heat of the boiler body can be fully utilized and energy source is saved.