Model CFC
ClearFire Commercial Boilers
51
Rev. 05-2012
Figure B5-45. Two Opening Outside Wall Method
B.
All Air From Outdoors
- If all combustion air will be received from outside the building (the mechanical
room equipment is linked with the outdoors), the following methods can be used:
1. Two Opening Method (Figure B5-45) - The mechanical equipment room
must be provided with two permanent openings, one terminating within
twelve inches from the top, and one opening terminating within twelve
inches of the bottom of the room.
2. The openings must be linked directly or by ducts with the outdoors.
3. Each opening must have a minimum free area of one square inch per
4,000 Btu per hour of total input rating of all equipment in the room,
when the opening is directly linked to the outdoors or through vertical
ducts.
4. The minimum free area required for horizontal ducts is one square inch
per 2,000 Btu per hour of total input rating of all the equipment in the
room.
GAS
VENT
CLEARFIRE
BOILER
WATER
HEATER
GAS
VENT
INTERIOR WALL
FRESH AIR OPENING
FRESH AIR OPENING
12" MINIMUM
12" MINIMUM