When may the diameter of a chimney need to be increased?

Increasing the diameter of a chimney is often necessary when a boiler experiences continual smoking. This situation indicates that the chimney may not be effectively handling the flue gases being produced by the combustion process. A proper chimney size is crucial for maintaining an adequate draft, which allows for efficient venting of combustion products. If the chimney is too narrow, it can lead to restricted airflow, causing smoke to back up into the boiler or living spaces.

For effective combustion, the stack needs to provide enough draft to remove smoke and gases, while also allowing for the proper air intake. If the diameter is insufficient, it can hinder the chimney's ability to create the necessary upward draft, which is essential for venting smoke and ensuring the complete burning of fuel. Thus, increasing the diameter can improve the chimney's performance by enhancing its ability to manage exhaust gases, reducing smoking and emissions.

Other situations, such as the chimney being too tall or too wide or needing adjustment for multiple boilers, do not directly address the efficiency of smoke removal in the same way as the issue of continual smoking does.