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C. Use the following opening calculation for P-K THERMIFIC
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
and including 1,000,000 Btu/Hr plus 1 sq. in. / 14,000 Btu/Hr (155 mm
opening must be either located at or ducted to a point not more than 18 in. (450 mm) or 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 appliance 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 addition 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.
NOTE:
1. The free area of a combustion air supply opening is calculated by deducting the blockage area of any fixed
louvers, grilles or screens from the total 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 Canadian Minimum Area of Combustion and Ventilation Air Openings
®
MACH
Boiler
Model
Input (Btu/Hr)
C1500H
C2000H
C2500
C3000
3,000,000
C4000
4,000,000
3.5.3
Flue Venting
This boiler is not certified for use with Type "B" vent nor with PVC venting.
®
MACH
C1500H/C2000H/C2500/C3000/C4000 boilers are dual certified as a Category II and Category IV appliances,
as defined in ANSI Z21.13/CSA 4.9, latest edition. The vent material must be as listed in the Table of Acceptable
Materials for Venting Systems in Section 3.5.1.2 above. The exhaust vent can be run horizontally or vertically.
Vent installations shall be in accordance with NFPA54/ANSI Z223.1, the National Fuel Gas Code, or CAN/CSA-
B149.1, the Natural Gas and Propane Installation Code, or applicable provisions of the local building codes.
Required Combustion Air
2
in
1,500,000
50
2,000,000
67
2,500,000
83
100
134
®
boilers or other natural draft or fan-assist appliances:
Opening
2
mm
32,258
43,226
53,548
64,516
86,451
22
MACH
2
/kW) in excess 1,000,000 Btu/Hr. This
Ventilation Air Opening
2
2
in
mm
10
6,452
10
6,452
10
6,452
10
6,452
13.4
8,645
®
Gas Fired Boiler
2
/kW) up to
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