- Section 304.51 fuel gas code

Standard method- Room must have a volume of 50 cubic feet per 1000 btuh of installed appliances for combustion or have outside air brought in.

An 80,000 btuh appliance has 80-1000’s (80,000/1000 = 80) Therefore, the room must have 80 x 50 cubic feet or at least 4000 cubic feet. This room has a volume of 20 x 18 x 8 = 2880 cubic feet. Since the appliance requires 4000 cubic feet, **the room is in a confined space** and needs outside air