Heat generator assembly comprising a main frame defining at least one combustion chamber, at least one closure/opening first door of a main window or opening for accessing said at least one combustion chamber, means for distributing a comburent air in said at least one combustion chamber, at least one container tank of a first fuel, at least one brazier in said at least one combustion chamber for the combustion of a first fuel, at least one burner at said at least one brazier, at least one supply duct or line of said first fuel from said at least one tank to said at least one brazier, as well as conveying means (14a, 14b) of said first fuel along said at least one duct supply or line up to said at least one brazier, the upper combustion surface of said at least one brazier is at a level which is higher than the upper face or fire bed of the base wall defining said at least one combustion chamber, said at least one brazier comprises at least one tubular body rising partially in the combustion chamber with respect to or from said base wall, and wherein said supply duct or line is mounted or opens into said at least one tubular body, said tubular body delimits a clearance or channel for the passage of the first fuel towards the top of said at least one brazier, characterized in that said at least one tubular body delimits at least one hole for the passage of comburent air, while the means for distributing a comburent air comprise a first distribution duct of the comburent air in said tubular body and from this in the area of the combustion chamber at the top of the brazier and around said at least one burner, wherein said at least one tubular body comprises an outer tubular wall and an inner tubular component fitted within the outer tubular wall, said tubular body comprising then a bottom wall partially closing the lower, in use, end of said outer tubular wall and defining a recess for fitting the supply duct or line or of a portion of the same, said inner tubular component presenting a top wall defining said upper surface or part of the same, and wherein among said outer tubular wall, said inner tubular component and said supply line or a section thereof is defined a manifold area of comburent air to be conveyed toward the upper surface of the brazier, after passing through the holes, said first distribution duct opening into the manifold area. said at least one brazier comprises at least one tubular body rising partially in the combustion chamber with respect to or from said base wall, and wherein said supply duct or line is mounted or opens into said at least one tubular body, said tubular body delimits a clearance or channel for the passage of the first fuel towards the top of said at least one brazier, characterized in that said at least one tubular body delimits at least one hole for the passage of comburent air, while the means for distributing a comburent air comprise a first distribution duct of the comburent air in said tubular body and from this in the area of the combustion chamber at the top of the brazier and around said at least one burner, wherein said at least one tubular body comprises an outer tubular wall and an inner tubular component fitted within the outer tubular wall, said tubular body comprising then a bottom wall partially closing the lower, in use, end of said outer tubular wall and defining a recess for fitting the supply duct or line or of a portion of the same, said inner tubular component presenting a top wall defining said upper surface or part of the same, and wherein among said outer tubular wall, said inner tubular component and said supply line or a section thereof is defined a manifold area of comburent air to be conveyed toward the upper surface of the brazier, after passing through the holes, said first distribution duct opening into the manifold area.