Looking at a chimney from the outside, one would never realize how complex this ventilation system actually is. The anatomy of your chimney has various parts, but one of the most important is the chimney liner. The liner can be made from a variety of materials, such as metal or clay, and is the route which exhaust gases escape from the fireplace or heating appliance.
Any time the specific use of a chimney is changed, the liner may need to be changed as well. For instance, if you are switching over from a traditional wood-burning fireplace to an oil-fired appliance, you must schedule an inspection of the chimney. This is actually required in order to ensure the new device is safe to use with the existing structure.
If the home has already been fitted for this appliance, you should still occasionally check to make sure the structure is okay and does not need to be replaced. Just because you have the structure inspected annually does not mean something cannot cause damage throughout the year requiring attention.
One of the more common signs that the liner has been compromised is in seeing discolored masonry work on the outside of the chimney, specifically darker areas or stains on the masonry work. If the liner is made from clay, you may actually see pieces of the liner falling down the chimney into the fireplace. Two more signs of liner failure are condensation and rapid creosote buildup.
If you see any of these signs, there is a very good chance the liner has been damaged and will need to be replaced. The safest route to take is to stop using the fireplace or appliance immediately and call a certified chimney sweep to inspect the structure to see the best course of action. If the liner does need replacing, HeatShield® may be a less costly option than a full liner replacement.
