Filter
Top Products
10
VI Air for Ventilation
WARNING
Outdoor combustion air must be piped to the air intake. Never pipe combustion air from areas containing
contaminates such as areas where swimming pool chemicals are stored. Contaminated combustion
air will damage the boiler and may cause property damage, personal injury or loss of life.
Air for combustion must always be obtained directly from outdoors, however suffi cient air for ventilation must
still be provided in the boiler room. Air for ventilation is required to keep various boiler components from
overheating and is always obtained from indoors. To ensure an adequate ventilation air supply, perform the
following steps:
Step 1: Determine whether the boiler is to be installed in a confi ned space - A confi ned space is defi ned by
the
Total the input of all appliances in the boiler room in thousands of BTU/hr. Round the result to the next A.
highest 1000 BTU/hr.
Find the volume of the room in cubic feet. The volume of the room in cubic feet is:B.
Length (ft) x width (ft) x ceiling height (ft)
In calculating the volume of the boiler room, consider the volume of adjoining spaces only if no doors
are installed between them. If doors are installed between the boiler room and an adjoining space, do
not consider the volume of the adjoining space, even if the door is normally left open.
Divide the volume of the boiler room by the input in thousands of BTU/hr. If the result is less than 50, the C.
boiler room is a confi ned space.
Example:
A MWC116 and a water heater are to be installed in a room measuring 6ft – 3 in x 7ft with an 8 ft ceiling. The
water heater has an input of 30000 BTU/hr:
Total input in thousands of BTU/hr = (116000 BTU/hr + 30000 BTU/hr) / 1000 = 146 MBTU/hr
Volume of room = 6.25 ft x 7 ft x 8 ft = 350 ft
3
350/146 = 2.40. Since 2.33 is less than 50, the boiler room is a confi ned space.
Step 2a: If the boiler is to be placed in a confi ned space, provide two openings into the boiler room, one near
the fl oor and one near the ceiling. The top edge of the upper opening must be within 12” of the ceiling and the
bottom edge of the lower opening must be within 12” of the fl oor (Fig 6.1). The minimum opening dimension is
3 inches.
If the MWC boiler is the only gas-burning appliance in the boiler room, these openings must each •
have a minimum free area of 54 square inches.
If other gas-burning appliances are in the boiler room, size the openings in accordance with the •
appliance manufacturer’s instructions or the National Fuel Gas Code
54 square inches even if opening requirements for other appliances are less.
,ANSI Z223.1.
Natural Gas and Propane Installation Code.
/NFPA 54 and/or CAN/CSA B 149.1National Fuel Gas Code
as having a volume less than 50 cubic feet per 1000 BTU/hr input of all appliances
installed in that space. To determine whether the boiler room is a confi ned space:
ANSI Z223.1.
/NFPA 54 and/or CAN/CSA B 149.1.
Minimum opening free area is
Air for combustion and ventilation, of the National Flue Gas Code, ANSI Z223.1/NFPA 54 CAN/CSA B 149.1
Natural Gas and Propane Installation Code, or applicable provisions of the local building codes.