Installation Guide

10
#ATEGORY)66ENTING
WARNING:
5PON COMPLETION OF THE FURNACE INSTALLATION
CAREFULLYINSPECT THE ENTIREmUE SYSTEM BOTH
INSIDEANDOUTSIDETHEFURNACETOASSUREITIS
PROPERLYSEALED,EAKSINTHEmUESYSTEMCAN
RESULTINSERIOUSPERSONALINJURYORDEATHDUE
TOEXPOSUREOFmUEPRODUCTSINCLUDINGCARBON
MONOXIDE
This furnace is classified as a “Category IV” appliance,
which requires special venting materials and installation
procedures. This section specifies installation requirements
for Conventional (1-pipe) and Direct Vent (2-pipe) piping.
For 1- pipe installations, install vent piping as described in
this section and provide air for combustion and ventilation
according to pages 7-10. The length of vent and
combustion air piping for either type of installation are
llisted in Table 1 (page 11).
Alternate Method of Providing Air from
Outside
If acceptable under local Codes, it is permitted to provide
outside air using one opening (See NFGC). Generally,
confined spaces must have two openings in the space for
combustion air. One opening must be within 12 inches of
the ceiling, and the other must be within 12 inches of the
floor. However, an alternative method recently adopted by
the NFGC uses one opening within 12 inches of the top
of the space. This method may be used if it is acceptable
to the local codes.
4HEFOLLOWINGCONDITIONSMUSTBEMET
1. The opening must start within 12” of the top of the
structure and connect with the out of doors through
vertical or horizontal ducts or be ducted to a crawl or
attic space that connects with the out of doors.
2. The opening must have a minimum free area of 1 sq.
in. per 3,000 Btu per hour of the total input rating of all
equipment located in the enclosure.
3. The free area must not be less than the sum of all the
areas of the vent connectors in the enclosure.
#ONVENTIONAL 6ENT 3YSTEMS  5NCONlNED
3PACES
An unconfined space is an area including all rooms not
separated by doors with a volume greater than 50 cubic
feet per 1,000 Btuh of the combined input rates of all
appliances which draw combustion air from that space.
In general, a furnace installed in an unconfined space will
not require outside air for combustion. However, in homes
built for energy efficiency (low air change rates), it may
be necessary to provide outside air to ensure adequate
combustion and venting, even though the furnace is located
in an unconfined space. See example below.
%XAMPLE:
A space with a water heater rated at 45,000 Btuh
input and a furnace rated at 75,000 Btuh requires a
volume of 6,000 cubic feet [50 x (45 + 75) = 6,000] to
be considered unconfined. If the space has an 8 foot
ceiling, the floor area of the space must be 750 sq. ft.
(6,000 / 8 = 750).
Figure 5.
#OMBUSTION!IR$RAWNFROM/UTSIDE
4HROUGH(ORIZONTAL$UCTS
4OTAL)NPUT2ATING
"TUH
-INIMUM&REE!REA
%ACH/PENING
Round Duct
$IAMETER
40,000 20 sq. In 5 inches
60,000 30 sq. In 6 inches
80,000 40 sq. In 7 inches
100,000 50 sq. In 8 inches
120,000 60 sq. In 9 inches
140,000 70 sq. In 10 inches
160,000 80 sq. In 10 inches
Furnace
Water
Heater
Air Ducts must be
at least 1 sq. in.
per 2,000 Btuh of
total input rating.
Vent or
Chimney
Air Duct
Air Duct
4OTAL)NPUT2ATING
"TUH
-INIMUM&REE!REA
%ACH/PENING
Round Duct
$IAMETER
40,000 10 sq. In 4 inches
60,000 15 sq. In 5 inches
80,000 20 sq. In 5 inches
100,000 25 sq. In 6 inches
120,000 30 sq. In 6 inches
140,000 35 sq. In 7 inches
160,000 40 sq. In 8 inches
NOTE:
Each opening to outside
must be at least 1 sq. in. per
4,000 Btuh of total input rating.
12" Max.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Furnace
Water
Heater
Vent or
Chimney
12"
Max
See
Note
See
Note
Figure 6. #OMBUSTION!IR$RAWNFROM/UTSIDE
4HROUGHAN%XTERIOR7ALL