Harsco Industrial C1500H Installation & Owner's Manual page 20

3.5.2 Combustion Air Materials and Sizes
Air Requirements – SCFM
®
MACH Boiler MODEL
C1500H
C2000H
C2500
C3000
C4000
Combustion air must be free from dust, lint, etc. The presence of such materials in the air supplied to the burner
could cause nuisance "Low Air" shutdowns or premature burner failure. The boiler should not be operated during
construction while the possibility of drywall dust, demolition dust, etc. exists.
The combustion air supply must be completely free of chemical fumes which may be corrosive when burned in the
boiler. Common chemicals which must be avoided are fluorocarbons and other halogenated compounds, most
commonly present as refrigerants or solvents, such as Freon, trichloroethylene, perchloroethylene, chlorine, etc.
These chemicals, when burned, form acids which quickly attack the boiler and the boiler stack. The result is improper
combustion and premature boiler failure.
Particular care should be taken when exhaust fans, compressors, air-handling units or other equipment may rob air
from the boiler. Note that this equipment might be in rooms other than the boiler room. This applies to both sealed
combustion and atmospheric room combustion air applications.
3.5.2.1 Air Inlet Requirements – United States (NFPA 54/ANSI Z223.1 & NFPA/ANSI 211)
When air is supplied from inside the building, the total required volume shall be the sum of the required volume for all
the appliances located in the mechanical room. Adjacent rooms furnished with fixed openings communicating directly
with the mechanical room are considered part of the required volume. The minimum volume is 50 ft
3
(4.8 m /kW) of installed appliance input capacity.
Openings used to connect indoor spaces to obtain the required minimum volume shall be sized as follows:

When rooms are on the same floor, each opening shall have an area equal to 1 square inch for each 1000 Btu/hr
2
(2200 mm / kW) of installed appliance input capacity, but not less than 100 square inches. One opening should
commence less than 12 inches above the floor and the other less than 12 inches below the ceiling. The minimum
dimension of air openings shall be 3 inches.

When rooms are on different floors, each opening shall have an area equal to 2 square inches for each 1000
2
Btu/hr (4400 mm / kW) of installed appliance input capacity.
Required SCFM
The air intake duct can be fabricated from PVC, CPVC, single wall
galvanized steel, or other suitable materials. The duct must be rigid
350
enough to maintain the full required cross sectional area under all
operating conditions. Proper sealing of the intake ductwork is necessary
to prevent infiltration of air from conditioned space. Joints in PVC or
467
CPVC must be cemented. For galvanized duct, wrap each joint and
seam with adhesive aluminum tape or other sealant. The installation of a
584
bird screen on the intake termination is recommended. Ensure that the
screen does not become blocked with snow, ice, insects etc. Combustion
air duct should be designed with .22"W.C. friction loss per 100' of duct.
629
839
Under no circumstances shall the boiler room ever be under a negative pressure.
20
®
MACH Gas Fired Boiler
3
per 1000 Btu/hr