What symptoms might suggest an issue with a heat exchanger?

The presence of yellow burner flames and soot buildup indicates a problem with the heat exchanger. This situation generally suggests that the combustion process is not functioning properly, which is often due to incomplete combustion of the fuel. As a result, instead of producing a clean, blue flame, the burner exhibits a yellow flame, which signifies the presence of unburned fuel. This inefficiency can lead to soot accumulation, which is a byproduct of the incomplete combustion process. If a heat exchanger is compromised, it may not effectively transfer the heat generated during combustion to the air or water being heated, ultimately affecting the system's efficiency and safety. Therefore, these symptoms are crucial for diagnosing potential issues with the heat exchanger, necessitating further inspection and maintenance to ensure safe and effective operation.