The combustion chamber is lined with vermiculite plates. Vermiculite is a very porous material that is sensitive to impact and must therefore be treated with care. This means you should not throw firewood into the combustion chamber, as this can cause the plates to break. Cracked plates are no reason for concern, but if cracks are larger than 5 mm or pieces have broken off, it is important that the plates are replaced. It is relatively easy to replace the plates yourself. Find out more and watch the video about how to replace the vermiculite plates in your wood-burning stove