[Cob] fire brick?

[Yun Que]

   Cat here

   I have been given conflicting responses to the use of fire brick in
   bread ovens?  A potter tells me that they will keep the oven hotter
   longer giving a longer baking time, and a slower cooling surface.  She
   told me that the oven will be relesing heat into the room two days
   after fire.  Much like a masonary or Russian stove.   A brick mason
   told me that fire brick is made to pass heat quickly to the surface
   and protect the interior of the stove from damage??? This is to get
   heat into the room faster and less heat in the fire box.  I just got a
   few boxes of curved fire brick at a scavanger sale.  I must
   decide where to use them.  The bread oven or the heating stove.  Ok so
   I got to figure that their are two kinds of fire brick? Or their is
   something that I'm not understanding about fire brick.  Most use I
   have seen it is layed loose into the stove and can be repalced. Anyone
   been up this ally got any suggestions?
   for the good of all C.