N80ESN/N80ESL(Series A): Installation, Start–Up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
7
2. For fan-assisted appliances such as this furnace:
A04003
If the following is applied to either equation:
• Iother = combined input of all other than fan-assisted appliances in
Btuh/hr
• Ifan = combined input of all fan-assisted appliances in Btuh/hr
• 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
.
1. Adjoining rooms can be considered part of a space if:
a. There are no closeable doors between rooms.
b. Combining spaces on same floor level. Each opening shall have
free area of at least 1 in.
2
/1,000 Btuh (2,000 mm
2
/kW) of the
total input rating of all gas appliances in the space, but not less
than 100 in.
2
(0.06 m
2
). One opening shall commence within 12”
(300 mm) of the ceiling and the second opening shall commence
within 12” (300 mm) of the floor. The minimum dimension of air
openings shall be at least 3 in. (80 mm) (see
).
c. Combining space on different floor levels. The volumes of
spaces on different floor levels shall be considered as
communicating spaces if connected by one or more permanent
openings in doors or floors having free area of at least 2
in.
2
/1,000 Btuh (4,400 mm
2
/kW) of total input rating of all gas
appliances.
*Air Changes/Hour
*Minimum opening size is 100 in.2 with minimum dimensions of 3 in. (76 mm).
*Minimum of 3 in. (76 mm), when type -B1 vent is used.
A03175
Fig. 7 – Air for Combustion, Ventilation, and Dilution from Indoors
2. An attic or crawlspace may be considered a space that freely
communicates with the outdoors provided there are adequate
permanent ventilation openings directly to outdoors having free
area of at least 1-in.
2
/4,000 Btuh of total input rating for all gas
appliances in the space.
3. In spaces that use the Indoor Combustion Air Method, infiltration
should be adequate to provide air for combustion, permanent
ventilation and dilution of flue gases. However, in buildings with
unusually tight construction, additional air
MUST
be provided
using the methods described in the Outdoor Combustion Air
Method section.
4. Unusually tight construction is defined as construction with:
a.Walls and ceilings exposed to the outdoors have a continuous,
sealed vapor barrier. Openings are gasketed or sealed and
b.Doors and openable windows are weatherstripped and
c.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.
Combination of Indoor and Outdoor Air
1. Indoor openings shall comply with the Indoor Combustion Air
Method below and,
2. Outdoor openings shall be located as required in the Outdoor
Combustion Air Method mentioned previously and,
3. Outdoor openings shall be sized as follows:
a.Calculate the Ratio of all Indoor Space volume divided by
required volume for Indoor Combustion Air Method below.
b.Outdoor opening size reduction Factor is 1 minus the Ratio in
a. above.
c.Minimum size of Outdoor openings shall be the size required
in Outdoor Combustion Air Method above multiplied by
reduction Factor in b. above. The minimum dimension of air
openings shall be not less than 3 in. (80 mm).
Volume
Fan
= 15ft
3
ACH
I
fan
1000 Btu/hr
Table 2 – Minimum Space Volumes for 100% Combustion, Ventilation, and Dilution from Indoors
ACH*
OTHER THAN FAN-ASSISTED TOTAL
(1,000’S BTUH GAS INPUT RATE
FAN-ASSISTED TOTAL
(1,000’S BTUH GAS INPUT RATE)
30
40
50
44
66
88
110
132
Space Volume (ft.
3
)
0.60
1,050
1,400
1,750
1,100
1,650
2,200
2,750
3,300
0.50
1,260
1,680
2,100
1,320
1,980
2,640
3,300
3,960
0.40
1,575
2,100
2,625
1,650
2,475
3,300
4,125
4,950
0.30
2,100
2,800
3,500
2,200
3,300
4,400
5,500
6,600
0.20
3,150
4,200
5,250
3,300
4,950
6,600
8,250
9,900
0.10
6,300
8,400
10,500
6,600
9,900
13,200
16,500
19,800
0.00
NP
NP
NP
NP
NP
NP
NP
NP
CIRCULATING AIR
DUCTS
6" MIN
(FRONT)
Ü
CIRCULATING AIR DUCTS
VENT THROUGH ROOF
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
12" MAX
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
12" MAX
UNCONFINED
SPACE
INTERIOR
HEATED
SPACE
CLEARANCE IN FRONT OF COMBUSTION AIR
O
P
E
N
IN
G
S
S
H
A
L
L
BE A
T LEAST 3 IN.
(305mm)
(152mm)
(305mm)
