What’s the most effective way to sweep and remove the creosote from a clay tile lined fireplace flue in a masonry chimney?

Honestly there is no single and no easy answer.  There are many different creosote types encountered and some require slightly different techniques.  The advancement of tools in the industry helps a lot and there are other factors as well such as rooftop or chimney access.  Bottom line if there is more than 2mm of creosote – it should be cleaned.

Historically the way to clean was from the top working down using either round or flat wire brushes; this can be effective when there is a powdery creosote buildup or even a thin layer of glaze present.

However, due to technology the rotary sweeping method from bottom up using nylon or poly rods attached to a drill has become quite effective and popular.  These also are very effective at removing the powdery creosote buildups as well as thin layers of creosote glaze – they can actually be more effective than the older brush method – although the older brush method does give a feel when using which is beneficial in a masonry chimney and lost in the power sweep.

However, if the creosote glaze becomes thick and is not flaky, then it can be very difficult to remove with traditional methods from either the top or the bottom.   Chains can be used – however this method often will damage the flue liner – and should be used with caution – especially true if the liner is old and in not great condition.  Chemicals can also be used to assist in removal of the glaze creosote buildups.  Some of these are designed to be used with fireplace/insert/woodstove in use – these often work well to help in reducing buildup but caution should be used if there is already significant creosote deposits present in the flue.  Having a fire in the appliance with large buildup is asking for a chimney fire!  There are products we can use when the appliance is not in use – but it has to remain in place for a time to effectively loosen the creosote and does become an expensive job.  It can however be very effective at loosening the hard deposits from the flue surface.

It is also important to note that most chimney sweeps also now have very sophisticated and expensive chimney cameras; capable of looking closely at the chimney walls from inside.  This can be done before the sweep to examine how and where the flue gases flow,  based upon buildup, or after the sweep is performed to closely examine for cracking in tiles.

Inspecting during the sweep is important and should be done by an professional Certified Chimney Sweep.  Which is why a proper Chimney Sweep is not going to be performed in less than an hour in most cases.  You should always hire a Certified Chimney Sweep or Certified Advanced Chimney Sweep.