What is the minimum area required for outdoor openings for a gas appliance with a 60,000 Btu/h input rating when drawing air through two horizontal ducts?

To determine the minimum area required for outdoor openings for a gas appliance with a 60,000 Btu/h input rating that draws air through two horizontal ducts, it’s important to refer to the guidelines provided in the National Fuel Gas Code or other relevant standards.

For gas appliances, the air requirements for combustion and ventilation are typically calculated based on the Btu/h input of the appliance. In general, the formula often used for calculating the required free area for outdoor air openings involves determining the total BTUs and then applying a specific calculation for open ventilation. A common rule of thumb suggests that for every 1,000 Btu/h input, approximately 1 square inch of free area is needed for air openings if ducts are used.

Given that the input rating is 60,000 Btu/h, using this guideline helps to establish a base requirement for air intake. The total area needed for the outdoor openings can be derived: 60 square inches for total intake via two ducts. However, since these two ducts would share the load, the minimum area for each duct would typically be half of the total required, but when determining the minimum total opening area, a common industry standard suggests rounding or adjusting that number to meet operational requirements and safety margins.