IndoorCombustionAir
standard method permits indoor air to be used for combustion and
ventilation air.
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 (4.8 cubic
meters per kW) input rating or homes with tight
construction may need outdoor air, supplied
through ducts, to supplement air infiltration for
proper combustion and ventilation of flue gases.
Standardand Known-Air-lnfiltrati0n 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 (4.8 cubic meters per
kW) input rating for all gas appliances installed in the space. The
The Known Air Infiltration Rate Method shall be used if the
infiltration rate isknown 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.
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in
personal injury or death.
An unconfined space or homes with tight
construction may not have adequate air infiltration
for proper combustion and ventilation of flue gases.
Most homes will require additional air.
i' MINIMUM SPACEVOLUME FOR 100% COMBUSTION AND VENTILATION AIR FROM INDOORS
OtherThanFan-AssistedTotal Fan-assistedTotal
30,000BTU 40,000BTU 50,000BTU 50,000BTU 75,000BTU 100,000BTU 125,000BTU
ACH (8,790kW) (11,720kW) (14,650kW) (14,650kW) (21,975kW) (29,300kW) (36,625kW)
ft3(m3)
0.60 1,050(29.7) 1,400(39.2) 1,750(49) 1,250(35) 1,875(52.5) 2,500(70) 3,125(87.5)
0.50 1,260(35.3) 1,680(47.04) 2,100(58.8) 1,500(42) 2,250(63) 3,000(84) 3,750(105)
0.40 1,575(44.1) 2,100(58.8) 2,625(73.5) 1,875(52.5) 2,813(78.8) 3,750(105) 4,688(131.3)
0.30 2,100(58.8) 2,800(78.4) 3,500(98) 2,500(70) 3,750(105) 5,000(140) 6,250(175)
0.20 3,150(88.2) 4,200(117.6) 5,250(147) 3,750(105) 5,625(157.5) 7,500(210) 9,375(262.5)
0.10 6,300(176.4) 8,400(235.2) 10,500(294) 7,500(210) 11,250(315) 15,000(420) 18,750(525)
0.00 NP NP NP NP NP NP NP
ACH = Air Changes per Hour
NP = Not Permitted
Table 2 Minimum Space Volumes were determined by using the
following equations from the National Fuel Gas Code ANSI
Z223.1/N FPA 54-2009, 9.3.2.2:
1. For appliances other than fan-assisted appliances (such
as a draft hood-equipped water heater), calculate using the
following equation:
Required Volume other _ 21ft3 ( |°ther )
ACH 1000 BTU H
where:
I other= all appliances other than fan-assisted input in BTUH
I fan = fan-assisted appliance input in BTUH
AOH = air change per hour (percent of volume of space
exchanged per hour, expressed as a decimal)
3. For purposes of this calculation, an infiltration rate greater
than 0.60 ACH shall not be used in the equations above.
! \
Required Volume other _ 59 m3 _ [ other )
ACH .293 kW
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 ctosable doors between rooms.
2. For fan-assisted appliances (such as this furnace),
calculate using the following equation:
RequiredVolume fan_ 15ft3 ( |fan )
ACH 1000 BTU H
! \
RequiredVolume fan _ .42 m3 _ [ fan )
ACH .293 kW
Combining spaces on the same story. Each opening shall
have a minimum free area of at least 1 in.2/1,000 BTUH (22
cm2/kW) of the total inputrating of all appliances in the space
but not less than 100 in.2 (645 cm2). One opening shall
commence within 12 in. (304.8 mm) of the top, and one
opening shall commence within 12 in. (304.8 mm) of the
bottom, of the enclosure. The minimum dimension of air
openings shall not be less than 3 in (76.2 mm).
Combining spaces in different stories. The volumes of spaces
on different stories shall be considered as communicating
spaces where such spaces are connected by one or more
12
Specifications are subject to change without notice
44001 102404
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