a dumb fire brick ??

[Garyvol]

My ?? is why do wood stoves have fire bricks inside cast iron or meatal stoves.
Maybe to protect the metal from a hotter flame so the metal lasts longer Just a guess.
-gary

 

[kalevi]

It is to hold more heat to allow the inside of the stove to stay at a more constant and higher temperature allowing you to get a cleaner burn.

 

[Martin Strand III]

It is to hold more heat to allow the inside of the stove to stay at a more constant and higher temperature allowing you to get a cleaner burn.

...and to protect the metal stove firebox from being overheated and failing.

Aye,
Marty