HVAC Journeyman Practice Exam 2025 - Free HVAC Practice Questions and Study Guide

In order to determine the largest fuel-burning appliance allowed in a room without combustion air openings, it's crucial to apply the guidelines set forth in the International Fuel Gas Code (IFGC) or similar local codes. For a room of the dimensions provided (100 feet wide, 20 feet long, and 8 feet high), the volume can be calculated as follows:

Volume = Width × Length × Height

= 100 ft × 20 ft × 8 ft = 16,000 cubic feet.

For appliances that do not have combustion air openings, the allowable input capacity in BTUs is based on the volume of the space. According to typical code provisions, the rule often suggests about 1000 BTUs of input capacity for every cubic foot of room volume when there are no combustion air openings.

Using this guideline, the calculation would go as follows:

16,000 cubic feet × 20 BTUs (a common factor that may vary regionally) = 320,000 BTUs.

This means that up to 320,000 BTUs can be utilized for fuel-burning appliances in that volume of space without requiring combustion air openings. Thus, in this scenario, the largest fuel-burning appliance that can be safely operated within the specified room dimensions