Air Supply - Engineered Method; One Opening Method - CleaverBrooks CFC Operation, Service & Parts Manual

2. Air Supply - Engineered Method

When determining boiler room air requirements for an 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 3-8.
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.
Part No. 750-263
GAS
VENT
CLEARFIRE
BOILER
Figure 3-7. One Opening Method
Section 3 — Stack and Intake Vent Sizing and Installation
GAS
VENT
WATER
HEATER
12" MINIMUM
FRESH AIR OPENING
EXTERIOR WALL
3-17