Carrier 58CU0A Series Installation, Start-Up, Operating And Service And Maintenance Instructions page 8

WARNING
!
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in death and/or
personal injury.
Many homes require air to be supplied from outdoors for
furnace combustion, ventilation, and dilution of flue gases.
The furnace combustion air supply must be provided in
accordance with this instruction manual.
CIRCULATING AIR
DUCTS
INTERIOR
HEATED
SPACE
CIRCULATING AIR DUCTS
2
*Minimum opening size is 100 in. with minimum dimensions of 3 in. (76 mm).
*Minimum of 3 in. (76 mm), when type ---B1 vent is used.
Fig. 8 - - Air for Combustion, Ventilation, and Dilution from
Indoors
The Standard Method:
1. The space has no less volume than 50 cubic feet per 1,000
Btuh of the maximum input ratings for all gas appliances
installed in the space and
2. The air infiltration rate is not known to be less than 0.40
air changes per hour (ACH).
The Known Air Infiltration Rate Method shall be used, if the
infiltration rate is known to be:
1. Less than 0.40 ACH and
2. 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 3 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.
Table 3 - - Minimum Space Volumes were determined by using
the following equations from the current edition of National Fuel
Gas Code ANSI Z223.1/NFPA 54, 9.3.2.2:
1. For other than fan- -assisted appliances, such as a draft
hood- -equipped water heater:
VENT THROUGH ROOF
12" MAX (305mm)
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
UNCONFINED
SPACE
(152mm)
6" MIN
(FRONT)
Ü
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
12" MA X (305mm)
A03175
Volume
Other
2. For fan- -assisted appliances such as this furnace:
Volume
Fan
If:
I
= combined input of all other than fan- -assisted appliances
other
in Btuh/hr
I
= combined input of all fan- -assisted appliances in Btuh/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
mm /kW) of the total input rating of all gas appliances
in the space, but not less than 100 in.
opening shall commence within 12" (300 mm) of the ceil-
ing 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 Fig. 8)
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 per-
manent openings in doors or floors having free area of
2
at least 2 in. /1,000 Btuh (4,400 mm
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 out-
doors having free area of at least 1- -in.
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 combus-
tion, permanent ventilation and dilution of flue gases.
However, in buildings with unusually tight construction,
additional air MUST be provided using the methods de-
scribed in the Outdoor Combustion Air Method section.
Unusually tight construction is defined as construction with:
a. Walls and ceilings exposed to the outdoors have a contin-
uous, 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
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.
8
I
= 21ft
3
other
ACH 1000 Btu/hr
I
= 15ft
3
fan
ACH 1000 Btu/hr
2
/1,000 Btuh (2,000
2
(0.06 m
2
/kW) of total input
2
/4,000 Btuh of total
shall comply with the
A04002
A004003
2
). One
Indoor