What does NFPA 31 dictate regarding chimney heights in relation to buildings?

NFPA 31 outlines safety standards for the installation of oil-burning appliances and related systems, including guidance on chimney heights. The guideline stating that chimneys must be at least 2 feet higher than any portion of the building within 10 feet is designed to ensure proper draft and minimize the risk of dangerous gases entering the building or creating hazardous conditions. This height requirement helps to effectively vent combustion gases above the roofline and allows for the appropriate dispersal of these gases, reducing backpressure and increasing the efficiency of the appliance.

Additionally, this standard takes into account various factors such as wind and structural interference that could affect the chimney's performance and safety. Ensuring that the chimney is sufficiently elevated compared to nearby structures helps maintain proper airflow and reduces the likelihood of downdrafts or other venting issues that could lead to safety hazards. This is crucial for the overall effectiveness of oil-burning appliances and the safety of the occupants in the building.