It is essential for the fuel burning system of the home. A chimney liner can include some essential components, such as the fuel burning appliances, which includes fireplace, gas\/oil burning furnace, woodstove, or even a combination of some of these venting appliances to single chimney along with the chimney liner, chimney flue, chimney structure, additional controlling features like fans, thermostats and dampers, together with some external features like dampers of top-sealing hydraulic parts casting and chimney caps.It is very important for all the components of a chimney liner to be in proper size and shape in relation to other parts. This will make the process of operation much easier, and it would also be safer for the home, considering the fact that the appliance will burn its fuel more efficiently. If any of the parts of a chimney liner system has not been sized properly, it could create problems eventually due to back flow of the noxious smoke and gases into the house and improper draft. If the chimney liner has been made using the best materials and has also been sized properly, chances are that it would improve overall venting of the combustion gases from the fireplace, furnace or woodstove. The furnace manufacturer would be able to comment on the required diameter of the chimney liner that should be venting the appliance in order to ensure its effective and smooth operation.If the chimney liner is narrower than usual for the chosen appliance, its venting effects will not be as good as it should; the liner will fail to carry smoke and combustion products properly up the flue that might eventually cause inefficient burning of fuel, leakage of the gases into the house and accumulation of moisture and creosote in the chimney liner. Similarly, if the chimney liner is too large compared to the normal size, it might inhibit the process of proper venting as it would not be able to heat up well from its bottom to the top to create a stronger updraft through the chimney.Insulation plays a crucial role on how the chimney liner would affect venting. The chimney liner must be insulated from its top to the bottom in case if it has been built on the outside walls of the house. However, if the chimney has been surrounded by some insulated rooms, it would be important to have the chimney liner properly insulated for that particular potion of a chimney that has an extension leading to the un-insulated roof line.Effective chimney liners would allow all the combustion gases to vent up the chimney to its top from where it would leave the house. This would slow down down-draft that is often caused as a result of cooler gases at the top of chimney to provide healthier updraft to pull smoke and gases out and keep the house cleaner.