MACH® Series
Gas-Fired Boiler
Installation
13
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
(2200 mm
2
/ 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
Btu/hr (4400 mm
2
/ kW) of installed appliance input capacity.
When combustion air is supplied from outside the building, the boiler room shall be provided with one or two openings
to ensure adequate combustion air and proper ventilation.
When using one permanent opening, the opening shall commence within 12 inches of the ceiling and shall
communicate directly with the outdoors or through a vertical or horizontal duct that communicates to the outdoors.
•
Minimum free area of the opening is 1 square inch for each 3000 Btu/hr (700 mm
2
/ kW) of installed appliance
input capacity, and
•
Not less than the sum of the areas of all vent connectors in the room.
When using two permanent openings, one opening shall commence within 12 inches above the floor and the other
within 12 inches below the ceiling, preferably on opposite walls. The openings shall communicate directly, or by way
of ducts, with free outdoor air. The minimum net free area of the openings shall be calculated in accordance with the
following:
•
When air is taken directly from outside the building, each opening (minimum of two, as outlined above), 1 square
inch for each 4,000 Btu per hour (550 mm
2
/kW) of total boiler input is required.
•
When air is taken from the outdoors through a vertical duct into the mechanical room, 1 square inch per 4,000 Btu
per hour (550 mm
2
/kW) of total boiler input is required.
•
When air is taken from the outdoors through a horizontal duct into the mechanical room, 1 square inch per 2,000
Btu per hour (1100 mm
2
/kW) of total boiler input is required.
NOTE:
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)
AIR SOURCE
INDOOR AIR SUPPLY
OUTDOOR AIR SUPPLY
TWO OPENINGS
MACH
®
MODEL
SAME FLOOR DIFF FLOORS ONE OPENING
DIRECT
VERT
DUCT
HORIZ
DUCT
C2500 2500 5000 833
625
625
1250
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 mm
2
),
whichever is greater.
B. Use the following opening calculation for P-K MACH
®
or ModuFire
®
FD boilers: