Abstract: Boiler systems having convection sections containing a set of boiler tubes having boiler tube inserts, boiler tubes for use in the convection section of a boiler system, and boiler tube inserts for boiler tubes for use in the convection section of a boiler system are provided herein. The boiler tube inserts are positioned in a first section of each boiler tube, where the first section extends from a front tube end the receives combustion gases from a furnace. The first section of the boiler tubes can be a plain tube section, and the boiler tubes can have a second section that includes a finned structure. The boiler tube inserts can be helical and can be made of a ceramic material.