The answer to 'furnace making loud noise' is that a loud furnace can be caused by several common issues, including worn or damaged components, airflow problems, or a buildup of dirt and debris. Symptoms may include banging, rattling, or screeching noises coming from the furnace.
Some potential solutions include replacing worn blower motors or bearings, cleaning the blower wheel and burners, and checking for blockages in the ductwork or air filters. However, it's important to note that furnace repairs can be dangerous and complex, so it's generally best to call a professional HVAC technician to diagnose and fix the problem, especially if the noise is persistent or the furnace is older.