13
Table4—Opening Dimensions-- In. (mm)
FURNACE
CASING
WIDTH
APPLICATION PLENUMOPENING FLOOROPENING
A B C D
14–3/16
(360)
UpflowAp plications on Combustible or Noncombustible Floor-
ing(KGASB subbase not required)
12---11/16
(322)
21---5/8
(549)
13---5/16
(338)
22---1/4
(565)
DownflowAp plications on Noncombustible Flooring (KGASB
subbasenot required)
12---9/16
(319)
19
(483)
13---3/16
(335)
19---5/8
(498)
Downflowap plications on combustible flooring (KGASB sub-
baserequired)
11---13/16
(284)
19
(483)
13---7/16
(341)
20---5/8
(600)
DownflowA pplications on Combustible Flooring with CNPV,
CNRV,CAR, orCAP Coil Assembly or KCAKC coil box
(KGASBsubbase not required)
12---5/16
(319)
19
(483)
13---5/16
(338)
20
(508)
17–1/2
(445)
UpflowAp plications on Combustible or Noncombustible Floor-
ing(KGASB subbase not required)
16
(406)
21---5/8
(549)
16---5/8
(422)
22---1/4
(565)
DownflowAp plications on Noncombustible Flooring (KGASB
subbasenot required)
15---7/8
(403)
19
(483)
16---1/2
(419)
19---5/8
(498)
Downflowap plications on combustible flooring (KGASB sub-
baserequired)
15---1/8
(384)
19
(483)
16---3/4
(425)
20---5/8
(600)
DownflowA pplications on Combustible Flooring with CNPV,
CNRV,CAR, orCAP Coil Assembly or KCAKC coil box
(KGASBsubbase not required)
15---1/2
(394)
19
(483)
16---1/2
(419)
20
(508)
21
(533)
UpflowAp plications on Combustible or Noncombustible Floor-
ing(KGASB subbase not required)
19---1/2
(495)
21---5/8
(549)
20---1/8
(511)
22---1/4
(565)
DownflowAp plications on Noncombustible Flooring (KGASB
subbasenot required)
19---3/8
(492)
19
(483)
20
(508)
19---5/8
(498)
Downflowap plications on combustible flooring (KGASB sub-
baserequired)
18---5/8
(473)
19
(483)
20---1/4
(514)
20---5/8
(600)
DownflowA pplications on Combustible Flooring with CNPV,
CNRV,CAR, orCAP Coil Assembly or KCAKC coil box
(KGASBsubbase not required)
19
(483)
19
(483)
20
(508)
20
(508)
24---1/2
(622)
UpflowAp plications on Combustible or Noncombustible Floor-
ing(KGASB subbase not required)
23
(584)
21---1/8
(537)
23---5/8
(600)
22---1/4
(565)
DownflowAp plications on Noncombustible Flooring (KGASB
subbasenot required)
22---7/8
(581)
19
(483)
23---1/2
(597)
19---5/8
(498)
Downflowap plications on Combustible flooring (KGASB sub-
baserequired)
22---1/8
(562)
19
(483)
23---3/4
(603)
20---5/8
(600)
DownflowA pplications on Combustible Flooring with CNPV,
CNRV,CAR, orCAP Coil Assembly or KCAKC coil box
(KGASBsubbase not required)
22---1/2
(572)
19
(483)
23---1/2
(597)
20
(508)
AIRDUCTS
GeneralRequirements
The duct system should be designed and sized according to
accepted national standards such as those published by: Air
ConditioningContractors Association(ACCA), Sheet Metal and
Air ConditioningContractors National Association(SMACNA)
or American Society of Heating, Refrigerating and Air
ConditioningEngineers (ASHRAE) or consult The Air Systems
Design Guidelines reference tables availablefrom your local
distributor. The duct system should be sized to handle the
required system design CFM at the design external static pressure.
The furnace airflow rates are provided in Table 5 -- AIR
DELIVERY--CFM(With Filter).
When a furnaceis installed so that the supply ducts carryair
circulated by the furnace to areas outside th e space containing the
furnace, the return air shall also be handled by duct(s) sealed to
the furnacecasing and terminating outside the spacecontaining
the furnace.
Secureductwork with properfasteners for typeof ductwork used.
Seal supply-- and return--ductconnections to furnacewith code
approvedtape or duct sealer.
NOTE: Flexibleconnections should beused between ductwork
and furnace to prevent transmission of vibration. Ductwork
passing through unconditioned spaceshould be insulated and
sealed to enhance system performance. When air conditionin g is
used,a vapor barrier is recommended.
Maintain a 1--in. (25 mm) clearance from combustib le materials
to supply air ductwork for a distance of 36 in. (914 mm)
horizontally from the furnace. See NFPA 90B o rlo cal code for
furtherrequirements.
Ductwork Acoustical Treatment
NOTE: Metalduct systems that do not have a 90 degree elbow
and 10 ft. (3 M) of mainduct to the first branch take--off may
require internal acoustical lining. As an alternative, fibrou s
ductwork may be used if constructed and installed in accordance
with the latest edition of SMACNA construction standard on
fibrousglass ducts. Both acoustical liningand fibrous ductwork
shallcomply with NFPA 90B as testedby UL Standard181 for
Class1 Rigid air ducts.
SupplyAir Connections
For a furnace not equippedwith a cooling coil, the outlet duct
shall be provided with a removable access panel. Thi s opening
shall be accessible when the furnace is installed and shall b eo f
such a size that the heat exchanger can b e viewed for possible
openings using light assistance or a probe can be insertedfor
sampling the air stream. The cover attachment shall preven t leaks.
310AAV