The part of the chimney into which the pipe goes is called the thimble. The thimble should go no further into the pipe than the inner surface of the chimney. It is ideal to have a clean-out door at the base of the chimney. This solves the problem of removing the stove pipe each time you want to clean the chimney. Never hook TV or CB antennas to masonry chimneys.
Wind can cause antennas to vibrate, which can weaken the mortar joints.
Prefabricated Chimney Units Masonry chimney units cannot be easily added to many existing homes. Consequently, a prefabricated metal chimney unit may be the best choice for wood stoves or fireplaces in these homes. The prefabricated chimney is also easier to install than a masonry unit. This movement of air cools the chimney. Some tests indicate that this may cool the chimney too much, however, and thus encourage creosote buildup.