A major component to keeping your stove clean and working efficiently is a chimney register plate. It is a part made of high quality galvanised steel with a hole in the middle for the flue pipe and acts as a secure closure so air cannot leak where the stove pipe and chimney flue join. If you don't have this part in place, you will lose a lot of heat and durt can fall on to the wood burner.
One main goal from switching to a wood burning stove or wood boiler is to save energy, and thus, save money. This seemingly small plate will make a significant difference in your heat and cost savings.