International comfort products N9MP1 Installation Instructions Manual page 9

Table 1
Free Area
BTUH BTUH
Input
Two Horizontal Ducts
Rating
(sq. in./2,000 BTUH)
50,000
75,000
80,000
100,000
125,000
EXAMPLE: Determining Free Area
Furnace Water Heater
100,000 +
Furnace Water Heater
100,000 +
Indoor Combustion Air
WARNING
!
CARBON MONOXIDE POISONING HAZARD.
Failure to supply adequate combustion air could
result in death or personal injury.
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 T bl 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--2002, 8.3.3.2:
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
440 01 1021 01
Minimum Free Area Required for Each Opening or Duct to Outdoors
(sq. in./3,000 BTUH)
25 sq. in.
37.5 sq. in.
40 sq. in.
50 sq. in.
62.50 sq. in.
30,000 = (130,000 ¸ 4,000)
30,000 = (130,000 ¸ 2,000)
through ducts,
Other Than Fan- Assisted Total
(1,000's Btuh)
40
1,400
1,680
2,100
2,800
4,200
8,400
NP
(
)
I
other
1000 Btu / hr
(
)
I
fan
1000 Btu / hr
Single Opening Two Vertical Ducts or Openings
16.7 sq. in.
25 sq. in.
26.7 sq. in.
33.3 sq. in.
41.7 sq. in.
Total Input
=
Total Input
=
Standard and Known- - Air- - Infiltration Rate Methods
ã ã ã ã NFPA & AGA
Indoor air is permitted for combustion and ventilation, if the Stan-
dard or Known- -Air- -Infiltration Rate Method is used.
The Standard Method may be used, if the space has no less vol-
ume than 50 cubic feet per 1,000 BTUH input rating for all gas ap-
pliances 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 in-
filtration 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
to
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 vol-
ume for the space.
50 50
1,750 1,250
2,100 1,500
2,625 1,875
3,500 2,500
5,250 3,750
10,500 7,500
NP NP
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 1² 2/1,000 BTUH (2,000
mm2/kW) of the total input rating of all gas appliances in the
space, but not less than 100 in2 (0.06 m2). Once opening
(sq. in./4,000 BTUH)
12.5 sq. in.
18.75 sq. in.
20.0 sq. in.
25 sq. in.
31.25 sq. in.
32.5 Sq. In. Vertical
65 Sq. In. Horizontal
Fan- assisted Total
(1,000's Btuh)
75 100
1,875 2,500
2,250 3,000
2,813 3,750
3,750 5,000
5,625 7,500
11,250 15,000
NP NP
Round Duct
(sq. in. /4,000 BTUH)
4²
5²
5²
6²
7²
3
)
125
3,125
3,750
4,688
6,250
9,375
18,750
NP
9