Model CFC
ClearFire Commercial Boilers
53
Rev. 05-2012
Figure B5-47. One Opening Method
Unconfined Space/
Engineered Design
When determining boiler room air requirements for unconfined space, the size of the
room, airflow, and velocity of air must be reviewed as follows:
1. Size (area) and location of air supply openings in the boiler room.
A. Two permanent air supply openings in the outer walls of the boiler room are
recommended. Locate one at each end of the boiler room, preferably below
a height of 7 feet. This allows air to sweep the length of the boiler. See
Figure B5-48.
B. Air supply openings can be louvered for weather protection, but they should
not be covered with fine mesh wire, as this type of covering has poor air flow
qualities and is subject to clogging with dirt and dust.
C. A vent fan in the boiler room is not recommended, as it could create a slight
vacuum under certain conditions and cause variations in the quantity of
combustion air. This can result in unsafe burner performance.
D. Under no condition should the total area of the air supply openings be less
than one square foot.
GAS
VENT
CLEARFIRE
BOILER
WATER
HEATER
GAS
VENT
EXTERIOR WALL
FRESH AIR OPENING
12" MINIMUM