What is the minimum outdoor ventilation air rate required for unvented infrared heaters per 1000 BTU/h?

The correct air ventilation rate for unvented infrared heaters is established to ensure adequate combustion and to prevent the accumulation of harmful gases, such as carbon monoxide, in indoor environments. According to relevant building codes and standards, including the guidelines from the American National Standards Institute (ANSI) and the National Fire Protection Association (NFPA), the required outdoor ventilation air rate for unvented infrared heaters is four cubic feet per minute (cfm) for every 1,000 BTU/h of heating capacity.

This ventilation rate is necessary to maintain safe indoor air quality and to provide sufficient oxygen for combustion processes. By adhering to this standard, you can help ensure that the use of these heaters does not create unsafe conditions in the space they occupy. The other options, while they may represent different ventilation rates, do not meet the established guidelines required for safe operation of unvented infrared heaters. Therefore, the selection of four cfm is aligned with safety regulations and best practices in ventilation for heating equipment.