Abstract: A thermal plant comprises a clear blue flame burner and a multi-tank boiler of stainless steel. The burner has a nosepiece welded to the boiler and a rear portion removably fixed to the nosepiece. The rear portion of the burner includes a labyrinth pathway for preheating the combustion air and a thermally insulating conduit for feeding fuel to an atomizer. The boiler has its furnace delimited by two water tanks, i.e. a main peripheral tank and end tank located downstream of the furnace and delimiting with the main tank a gap through which flue gases are conveyed to give off heat to the water in the tanks.