Wikipedia places the coal bunker theories in its Titanic Conspiracy Theories page.

There does at least seem to be some truth, or at least there was a bunker fire but as far as I can make out, the consensus amongst experts is that the event made no difference to the fate of the ship.

I guess one can take things either way (although I will side with the debunkers on this on) but one page attempting to summarise a response to one broadcast promotiing a version of the theories is here.