I had one of those they are called Chimnias The spelling is wrong . Their Ok but it creates a lot of smoke . I live in the City and my neighbours complained so i had to stop using it .
They are usually a pretty soft terra cotta that would probably fail at high temperature. They sometimes come up for free when they get a little ugly. I could see using one or several encased in cob as either a bell for a very small system or as an elbow, when clay tile is used for a cob encased flue.
He loves you so much! And I'm baking the cake! I'm going to put this tiny ad in the cake:
The new permaculture playing cards kickstarter is now live!