Harsco Industrial 1004905923 Installation & Owner's Manual page 15

NOTICE!
1. The required size of openings for combustion and ventilation air shall be based on the net free area of the
opening.
2. Screens shall be not smaller than ¼"
3. Motorized louvers shall be interlocked with the appliance so that they are proven open prior to main burner
ignition and operation.
Table of US Minimum area of ventilation openings per boiler (sq inches)
MFD SAME FLOOR
MODEL
N2500
N3000
3.5.2.2 Air Inlet Requirements – Canada (CAN/CSA B149.1)
A. Ventilation of the space occupied by fuel burning appliance(s) or equipment shall be supplied by a ventilation
opening at the highest practicable point communicating with the outdoors. The total cross sectional area of
the ventilation opening must be either 10% of the net free area required for combustion air or 10 sq. in. (6500
2
mm ), whichever is greater.
B. Use the following opening calculation for MACH
When combustion air is supplied for a forced draft burner by natural airflow from the outdoors and there is no
draft regulator or draft hood in the same space, there shall be a permanent opening with a cross sectional ar-
ea not less than 1 sq. in/ 30,000 Btu/Hr (70 mm
must not interfere with the ventilation air opening defined in paragraph A.
C. Use the following opening calculation for P-K THERMIFIC
ances:
When combustion air is supplied for natural or fan-assisted burners by natural airflow from the outdoors, there
shall be a permanent opening with a cross sectional area not less than 1 sq. in/ 7000 Btu/Hr (321 mm
up to and including 1,000,000 Btu/Hr plus 1 sq. in. / 14,000 Btu/Hr (155 mm
This opening must be either located at or ducted to a point not more than 18 in. (450 mm) nor less than 6 in.
(150 mm) above floor level. This opening is in addition to the ventilation air opening defined in paragraph A.
D. When combustion air is supplied by natural airflow into a space containing both types of appliances described
in paragraphs B and C, the cross sectional area of the opening shall be not less than the sum of the cross
sectional areas for all appliances in the space as calculated by the applicable method . This opening is in ad-
dition to the ventilation air opening defined in paragraph A.
E. When a duct is used to meet the requirement for combustion air supply, as described in paragraphs A through
D, above, the opening of the duct shall be located so there is no possibility of cold air affecting steam or water
piping, electrical equipment or mechanical equipment.
F. When combustion air is supplied by mechanical means, an airflow-sensing device must be installed. It must
be wired into the pre-ignition limit string to prevent the burner from starting or to stop an operating burner in
case of air supply failure.
G. When all combustion air is supplied through a make-up air heater, and the appliance is interlocked to the
heater, the requirements of paragraphs A through F do not apply.
INDOOR AIR SUPPLY
DIFF FLOORS
2500 5000
3000 6000
®
MODU-FIRE Forced Draft Gas-Fired Boiler 2500-3000
AIR SOURCE
OUTDOOR AIR SUPPLY
ONE OPENING
833.3
1000
®
condensing boilers or MODU-FIRE
2
/kW) of the total rated input to the burner(s). This opening
®
boilers or other natural draft or fan-assist appli-
15
TWO OPENINGS
VERT
DIRECT DUCT
625 625
750 750
®
Forced Draft boilers:
2
/kW) in excess 1,000,000 Btu/Hr.
HORIZ
DUCT
1250
1500
2
/kW)