Bung: Some sites suggest 2 x 230x115x25 bricks and that there may be bricks at the bottom of the firebox. On our Logaire I was able to rotate broken side bricks to the bottom and the virtually new condition ones from the bottom to the worst side. The bottom is normally covered in ash and many brands don't bother with bricks there.
Not sure if we have a brick at the bottom. Due to illness we have been running the fire 24/7 and the ash is fairly thick. I have been waiting for a good moment to let things cool down. It would be great if I could rotate a brick but I'm not sure of that yet. I have seen instruction manuals for this model but haven't gone through one yet. I need to know more before I start playing with it.