International comfort products N8MXL Installation Instructions Manual page 7

All fuel−burning equipment must be supplied with air for fuel
combustion. Sufficient air must be provided to avoid negative
pressure in the equipment room or space. A positive seal
must be made between the furnace cabinet and the
return−air duct to prevent pulling air from the burner area and
from draft safeguard opening.
Figure 5 − Installation in a Garage
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
When the furnace is installed in a residential garage,
the burners and ignition sources must be located at
least 18 inches above the floor. The furnace must be
located or protected to avoid damage by vehicles.
When the furnace is installed in a public garage,
airplane hangar, or other building having a hazardous
atmosphere, the furnace must be installed in
accordance with the NFGC.
Table 2 – Minimum Free Area Required for Each Combustion Air Opening or Duct to Outdoors
TWO HORIZONTAL DUCTS
(1 SQ. IN./2,000 BTUH)
FURNACE
(1,100 SQ. MM/KW)
INPUT
(BTUH)
Free Area of Open-
ing and Duct
(sq. in. / sq. mm)
44,000 22 (14193)
66,000 33 (21290)
88,000 44 (28387)
110,000 55 (35484)
132,000 66 (42581)
WATER
FURNACE
HEATER
110,000 + 30,000
66,000 + 40,000
88,000 + 30,000
441 01 1421 01
18−IN. (457.2 mm)
MINIMUM TO BURNERS
A93044
Round Duct Free Area of Open-
Diameter
(in./mm) (sq. In. / sq. mm)
6 (152)
7 (178)
8 (203)
9 (229)
10 (254)
EXAMPLES: Determining Free Area
TOTAL INPUT
= (140,000 divided by 4,000)
= (106,000 divided by 3,000)
= (118,000 divided by 2,000)
Specifications are subject to change without notice.
!
PERSONAL INJURY AND/OR PROPERTY
DAMAGE HAZARD
Improper use or installation of this furnace may cause
premature furnace component failure.
This gas furnace may be used for heating buildings
under construction provided that:
−The furnace is permanently installed with all electrical
wiring, piping, venting and ducting installed according to
these installation instructions. A return air duct is
provided, sealed to the furnace casing, and terminated
outside the space containing the furnace. This prevents a
negative pressure condition as created by the circulating
air blower, causing a flame rollout and/or drawing
combustion products into the structure.
−The furnace is controlled by a thermostat. It may not be
"hot wired" to provide heat continuously to the structure
without thermostatic control.
−Clean outside air is provided for combustion. This is to
minimize the corrosive effects of adhesives, sealers and
other construction materials. It also prevents the
entrainment of drywall dust into combustion air, which
can cause fouling and plugging of furnace components.
−The temperature of the return air to the furnace is
maintained between 55_F (13_C) and 80_F (27_C), with
no evening setback or shutdown. The use of the furnace
while the structure is under construction is deemed to be
intermittent operation per our installation instructions.
−The air temperature rise is within the rated rise range on
the furnace rating plate, and the gas input rate has been
set to the nameplate value.
−The filters used to clean the circulating air during the
construction process must be either changed or
thoroughly cleaned prior to occupancy.
−The furnace, ductwork and filters are cleaned as
necessary to remove drywall dust and construction
debris from all HVAC system components after
construction is completed. −Verify proper furnace
operating conditions including ignition, gas input rate, air
temperature rise, and venting according to these
installation instructions.
SINGLE DUCT OR OPENING
(1 SQ. IN./3,000 BTUH)
(734 SQ. MM/KW)
Round Duct
ing and Duct Diameter
(in. / mm)
14.7 (9484) 5 (127)
22 (14193) 6 (152)
29.3 (18903) 7 (178)
36.7 (23677) 7 (178)
44 (28387) 8 (203)
= 35.0 Sq. In. for each two Vertical Ducts or Openings
= 35.3 Sq. In. for a Single Duct or Opening
= 59.0 Sq. In. for each of two Horizontal Ducts
CAUTION
TWO OPENINGS OR VERTICAL
DUCTS
(1 SQ. IN./4,000 BTUH)
(550 SQ. MM/KW)
Free Area of Round Duct
Opening and Duct Diameter
(sq. In. / sq. mm) (In./mm)
11 (7097) 4 (102)
16.5 (10645) 5 (127)
22 (14193) 6 (152)
27.5 (17742) 6 (152)
33 (21290) 7 (178)
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