When using horizontal ducts, how much free area should each opening have per 2,000 Btu/hour of total input rating of all appliances?

The requirement for free area for openings in horizontal ducts is aligned with ventilation needs for gas appliances. Each opening should provide a specific free area to ensure that the appliances receive sufficient combustion air to function properly and safely.

In this case, the guideline indicates that each opening must have a free area of 1 square inch for every 2,000 Btu/hour of total input rating of all appliances. This standard is vital to prevent inadequate ventilation, which can lead to poor appliance performance and potential safety hazards, such as the buildup of harmful gases.

Understanding this standard helps inspectors recognize proper installation practices and maintain compliance with safety and efficiency requirements in residential properties. Therefore, acknowledging that the correct answer is 1 square inch of free area per 2,000 Btu/hour reflects the critical nature of adequate ventilation and air supply in homes using gas appliances.