BOILER BOOK CFC-E ENGINEERING DATA
36
Figure 28. Two Opening Ducted Method
C. One Opening Method (Figure 29) - One permanent opening, commencing within 12 inches
of the top of the enclosure, shall be provided.
1. The equipment shall have clearances of at least 1 inch from the sides and back and 6
inches from the front of the appliance.
2. The opening shall directly communicate with the outdoors and shall have a minimum free
area of 1 square inch per 3000 BTU's per hour of the total input rating of all equipment
located in the enclosure, and not less than the sum of the areas of all vent connectors in
the confined space.
3. Refer to the NFGC, Section 8.3 for additional information.