What is the minimum horizontal distance required for mechanical draft systems?

The minimum horizontal distance required for mechanical draft systems is 4 feet. This distance is crucial to ensure that the systems operate efficiently and safely. Mechanical draft systems, which include devices like exhaust fans and forced air systems, rely on the movement of air to expel combustion gases from appliances. Adequate distance helps to prevent backdrafts, ensures proper ventilation, and minimizes the risk of harmful gases re-entering the building.

The specification of 4 feet provides a buffer that allows air to flow freely without obstruction, which is vital for maintaining the necessary airflow dynamics. This requirement also aids in preventing the potential blending of combustion air with exhaust gases, further enhancing safety and operational efficiency in accordance with building and safety codes.