Indoor Combustion Air; Standard And Known- Air- Infiltration Rate Methods - Arcoaire N9MP1 Installation Instruction

Indoor Combustion Air

WARNING
!
CARBON MONOXIDE POISONING HAZARD.
Failure to follow this warning could result in
personal injury or death.
Most homes will require additional air from
outdoors for combustion and ventilation. A space
with at least 50 cubic feet per 1,000 BTUH input
rating or homes with tight construction may need
outdoor air, supplied
supplement air infiltration for proper combustion
and ventilation of flue gases.
MINIMUM SPACE VOLUME FOR 100% COMBUSTION AND VENTILATION AIR FROM INDOORS (ft
Table 2
ACH 30
0.60 1,050
0.50 1,260
0.40 1,575
0.30 2,100
0.20 3,150
0.10 6,300
0.00 NP
NP = Not Permitted
Table 2 Minimum Space Volumes were determined by using the
following equations from the National Fuel Gas Code ANSI
Z223.1/NFPA 54--2006, 9.3.2.2:
1. For other than fan- -assisted appliances such as a draft
hood--equipped water heater,
3
21 ft
Volume
=
other
ACH
2. For fan- -assisted appliances such as this furnace,
3
15 ft
Volume
=
fan
ACH
If:
I = combined input of all other than fan- -assisted
other
appliances in Btu/hr
I = combined input of all fan- -assisted appliances in Btu/hr
fan
ACH = air changes per hour (ACH shall not exceed 0.60).
The following requirements apply to the Standard Method and to
the Known Air Infiltration Rate Method.
• Adjoining rooms can be considered part of a space, if there
are no closable doors between rooms.
Combining spaces on the same floor level. Each opening
•
shall have a free area of at least 1 in@/1,000 BTUH (2,000
mm@/kW) of the total input rating of all gas appliances in the
space, but not less than 100 in@ (0.06 m@). One opening shall
commence within 12" of the ceiling and the second opening
440 01 1024 01
through ducts, to
Other Than Fan- Assisted Total
(1,000's Btuh)
40 50
1,400 1,750
1,680 2,100
2,100 2,625
2,800 3,500
4,200 5,250
8,400 10,500
NP NP
(
)
I
other
1000 Btu / hr
(
)
I
fan
1000 Btu / hr
Specifications are subject to change without notice

Standard and Known- Air- Infiltration Rate Methods

© NFPA & AGA
Indoor air is permitted for combustion and ventilation, if the
Standard or Known- -Air- -Infiltration Rate Method is used.
The Standard Method may be used, if the space has no less
volume than 50 cubic feet per 1,000 BTUH input rating for all gas
appliances installed in the space. The standard method permits
indoor air to be used for combustion and ventilation air.
The Known Air Infiltration Rate Method shall be used if the
infiltration rate is known to be less than 0.40 air changes per hour
(ACH) and equal to or greater than 0.10 ACH. Infiltration rates
greater than 0.60 ACH shall not be used. The minimum required
volume of the space varies with the number of ACH and shall be
determined per Table 2 or Equations 1 and 2. Determine the
minimum required volume for each appliance in the space, and
add the volumes together to get the total minimum required
volume for the space.
Fan- assisted Total
(1,000's Btuh)
40 50 60
1,000 1,250 1,500
1,200 1,500 1,800
1,500 1,875 2,250
2,000 2,500 3,000
3,000 3,750 4,500
6,000 7,500 9,000
NP NP NP
shall commence within 12" of the floor.
dimension of air openings shall be at least 3".
Combining spaces on different floor levels. The volumes of
•
spaces on different floor levels shall be considered
communicating spaces if connected by one or more
permanent openings in doors or floors having a free area of at
least 2 in@/1,000 Btuh (4,400 mm
all gas appliances.
• An attic or crawl space may be considered a space that freely
communicates with the outdoors provided there are adequate
ventilation openings directly to outdoors. Openings MUST
remain open and NOT have any means of being closed off.
Ventilation openings to outdoors MUST be at least 1 square
inch of free area per 4,000 BTUH of total input rating for all gas
appliances in the space.
• In spaces that use the Indoor Combustion Air Method,
infiltration should be adequate to provide air for combustion,
ventilation and dilution of flue gases. However, in buildings
with unusually tight construction, additional air MUST be
provided using the methods described in section titled
Outdoor Combustion Air Method:
Unusually tight construction is defined as Construction with:
•
1. Walls and ceilings exposed to the outdoors have a
continuous, sealed vapor barrier. Openings are gasketed
or sealed and
2. Doors and openable windows are weather stripped and
3. Other openings are caulked or sealed. These include
joints around window and door frames, between sole
plates and floors, between wall--ceiling joints, between
wall panels, at penetrations for plumbing, electrical and
gas lines, etc.
3
75 100 125
1,875 2,500 3,125
2,250 3,000 3,750
2,813 3,750 4,688
3,750 5,000 6,250
5,625 7,500 9,375
11,250 15,000 18,750
NP NP NP
The minimum
@ /kW) of total input rating of
)
11