Introduction
1-4
IC-SA-1511 (02/2014)
V/LNV Series Manual
1.4.1 — Boiler Room Combustion Air
When determining boiler room air requirements, the size of the room, airflow, and velocity of air must be
reviewed as follows:
fpm: Feet per Minute
cfm: Cubic Feet per Minute
Example: Determine the area of the boiler room air supply openings for one (1) 300 hp boiler at 800 feet
altitude. The air openings are to be 5 feet above floor level.
1.
Air required: 300 x 10 = 3000 cfm
2.
Air velocity: Up to 7 feet - 250 fpm
3.
Area required: Area = cfm = 3000/250 = 12 sq-ft total
4.
Area/Opening: 12/2 = 6 sq-ft/opening (2 required)
Size (area) and location
of air supply openings in
boiler room:
Two (2) permanent air supply openings in the outer walls of the boiler room are
recommended. Locate one (1) at each end of the boiler room, preferably 7 foot or
lower. This allows air to sweep the length of the boiler.
A boiler room vent fan is not recommended. Under certain conditions, these fans
can cause a light vacuum and “steal” combustion air from the burner resulting in
unsatisfactory combustion performance.
A vent fan in the boiler room is not recommended, as it could create a light
vacuum under certain conditions and cause variations in the volume of
combustion air. This can result in unsatisfactory burner performance.
Under no condition should the total area of the air supply openings be less than (1)
square foot.
Size the openings by using the formula: Area (sq-ft) = cfm/fpm
Amount of air required
(cfm):
Combustion Air = Rated bhp x 8 cfm/bhp.
Ventilation Air = Maximum bhp x 2 cfm/bhp.
Total recommended air = 10 cfm/bhp – up to 1000 feet elevation. Add 3% more
per 1000 feet of added elevation.
Acceptable air velocity in
Boiler Room (fpm):
From floor to (7) foot height – 250 fpm
Above (7) foot height – 500 fpm