CleaverBrooks CFC-500 Operation, Service And Parts Manual page 69

• Area required: Area = cfm/fpm = 1,080/250 = 4.32
square feet total.
• Area/Opening: 4.32/2 = 2.16 sq-ft/opening (2 required).
Consult local codes, which may supersede these requirements.
If combustion air will be drawn directly from the outside by means of
a duct connected to the burner air intake, use the following as a
guide:
1. Install combustion air vent (direct vent combustion) in
accordance with the boiler's Operating and Maintenance
manual.
2. Provide for adequate ventilation of the boiler room or
mechanical equipment room.
3. In cold climates, and to mitigate potential freeze-up of the intake
pipe, it is highly recommended that a motorized sealed damper
be used to prevent the circulation of cold air through the boiler
during non-operating hours.
4. Refer to Figure 3-2 and Figure 3-4 for suggested piping of direct
vent combustion installations. Figure 3-9 shows the optional
direct vent combustion kit providing easy adaptation of the
contractor supplied air duct to boiler connection. Refer to Table
3-2 for sizing the direct vent combustion air pipe.
FAN/BLOWER
VENTURI
AIR SUPPLY LINE
Figure 3-9. Optional Direct Vent Combustion Kit
Part No. 750-263
Notice
Section 3 — Stack and Intake Vent Sizing and Installation
Direct Vent Combustion
3-19