If you notice several cracks through the entire flue and replacing the clay tiles is not an option you can choose to have a professional service create a new flue by placing a mold inside the flue then pumping cement around it.
Clay chimney liner replacement.
The process involves putting an inflatable mold bladder down the chimney.
They help keep your chimney drawing and operating properly while insulating it against fire.
If your chimney flue gets.
A better approach and the one used by most chimney repair masons who are not going to simply reline the flue is to remove all of the damaged materials down to sound chimney flue liner and brick or block then rebuild with new clay flue liner and brick or block adding an appropriate chimney cap and top seal.
A clay tile liner is a good choice when you are building a new fireplace because the materials are inexpensive and the liner will have a long life.
It is not a good choice for a replacement liner.
It is incredibly challenging and expensive to install a new clay tile liner or repair an old one after the chimney has been built.