Masonry chimneys are commonly constructed with an inner liner of clay tiles designed to keep the heat of the flue gasses inside the chimney. This prevents the chimney from overheating and potentially igniting nearby combustible material, such as the framing and walls of the building to which the chimney is attached. The liner also keeps harmful flue gasses, moisture, smoke, creosote, and other combustion products from seeping through the chimney and leaking into the building. A secure lining system is therefore critical to ensure the safety of the chimney and the health of the occupants of the attached structure.
If a liner was not installed in a chimney system, or if the original liner cracks, crumbles or deteriorates over time, a new liner should be installed. One common way to reline a chimney has been with stainless steel relining pipe. With this method a round or oval stainless steel liner is installed in the chimney. The metal pipe can be either rigid or somewhat flexible, with flexible liners being used most commonly in chimneys with offsets. Alternatively, an aluminum or other metal liner may be used in place of stainless steel.
One problem associated with metal chimney liners such as stainless steel is that the liner is susceptible to attack by certain acids and chemicals that are the byproducts of combustion (flue gases). Also, metal chimney liners are prone to disfiguration when subjected to high temperatures such as may be faced during a chimney fire.
As an alternative to a metal lining system, a cast-in-place liner may be used. With a cast-in-place liner a round or oval bladder (or a series of bladders for larger openings) is installed in the chimney and a masonry material is subsequently poured around the inflated form. After the material has cured, the bladder is deflated and removed, leaving the new masonry material as a liner in the chimney.
While all of the above systems provide clear benefits, they all have disadvantages as well. For example, metal lining systems are generally not good insulators, making them less effective against heat transfer from the flue to the surrounding structure unless a heavy insulating blanket is used around the liner. Cast-in-place systems may be good insulators, but they tend to significantly reduce the size of the flue. In addition, cast-in-place systems are less effective when the existing chimney is weak or crumbling and cannot adequately support the freshly poured masonry material.
In view of the above it can be seen that a need exists for an improved system for relining a chimney. The present invention addresses that need.