Payne PG9MXA Installation, Start-Up, And Operating Instructions Manual page 20

DUCTS
TO
O UTDOORS
12 " MAX
(305mm)
1 SQ IN.
PER 2000 B
BTUH*
DUCT S
TO
OUTDOORS
1 SQ IN.
PER 2000
A
BTUH*
12 " MAX
(305mm)
CIRCULA TING AIR DUCT S
Fig. 18 - - Air for Combustion, Ventilation, and Dilution
for Outdoors
1. For other than fan-assisted appliances, such as a draft
hood-equipped water heater:
2. For fan-assisted appliances such as this furnace:
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.
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
(2,000 mm /kW) of the total input rating of all gas
appliances in the space, but not less than 100 in.
2
(0.06 m ). One opening shall commence within 12 in.
(305 mm) of the ceiling and the second opening shall
commence within 12 in. (305 mm) of the floor. The
minimum dimension of air openings shall be at least
3 in. (76 mm). (See Fig. 19.)
1 SQ IN.
PER 4000
BTUH*
12 "
D
(305mm)
MAX
VENT
THR OUGH
F
R OOF
1 SQ IN .
PER
4000
BTUH*
1 SQ IN .
PER
4000
BTUH*
E
G
12 "
(305mm)
MAX
C
12 " MAX
(305mm)
DUCT
1 SQ IN.
TO
PER 4000
OUTDOORS
BTUH*
A03174
A04002
A04003
2
/1,000 Btuh
2
CIRCULATING AIR
DUCTS
INTERIOR
HEATED
SPACE
CIRCULATING AIR DUCTS
Fig. 19 - - Air for Combustion, Ventilation, and Dilution
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
(4,400 mm /kW) of total input rating of all
gas appliances.
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
(645.1 mm /1.17 KWh) 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.
Unusually tight
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.
20
VENT THROUGH ROOF
12" MAX (305mm)
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
UNCONFINED
SPACE
6" MIN (152mm)
(FRONT)
Ü
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
12" MA X
(305mm)
from Indoors
2
/1,000 Btuh
2
/4,000 Btuh
construction is defined
A03175
as