For combustion air drawn from a room with an 8' ceiling and dimensions of 12'X16' with a 12"X16" duct, what is the maximum BTU input allowable?

To determine the maximum BTU input allowable for combustion air drawn from a room, you first need to calculate the volume of the room and the capacity of the supply duct.

The volume of the room can be determined by multiplying its dimensions: 12 feet long x 16 feet wide x 8 feet high, which equals 1,536 cubic feet. When it comes to combustion appliances that draw air from indoor spaces, a typical requirement is to have at least 50 cubic feet of room volume for every 1,000 BTUs of input. Therefore, for a volume of 1,536 cubic feet, you can calculate:

1,536 cubic feet / 50 cubic feet per 1,000 BTUs = 30.72 (which translates to a maximum of 30,720 BTUs).

Since the duct supplied has adequate sizing to allow sufficient combustion air exchange, and the calculated BTUs align with this duct capacity, 30,720 BTUs is indeed the correct maximum input allowable. This consideration ensures that the combustion process can occur safely and efficiently without the appliance drawing air from an improperly ventilated space.