The manufacturers of wood-fired boilers choose refractory concrete over vermiculite and ceramic fibre primarily for its high mechanical durability and for raising combustion chamber temperatures, which increases a boiler’s efficiency and its service life.
Shaped blocks used as doors for stoking chambers serve as insulation shielding and protect against physical and chemical damage. Even though insulation mats provide better thermal insulation than these shapes, they are not sufficient thermal insulation on their own. That’s why we recommend combining both methods—shapes and mats—to minimize heat leakage into the jacketing of doors or boiler bodies.
For combustion chamber doors, we recommend both types of shaped blocks—insulation and accumulation blocks. Accumulation blocks shield door fillings, preventing excessive thermal wear to their construction and guiding the flow of gases into the combustion paths. Insulation blocks for combustion chamber doors serve for shielding and protection, similarly as do those for stoking chamber doors.
Here’s a look at the properties of the mixtures that we typically use when manufacturing shaped blocks for doors: