International comfort products N8MXL Installation Instructions Manual page 24

4. The input rating of each space heating appliance is
greater than the minimum input rating given in Table 9
for the local 99% Winter Design Temperature. Chim-
neys having internal areas greater than 38 square
inches require furnace input ratings greater than the in-
put ratings of these furnaces. See footnote at bottom of
Table 9, and
5. The authority having jurisdiction approves.
If all of these conditions cannot be met, an alternative venting
design shall be used, such as the listed chimney adapter kit
with these furnaces, which are listed for use with the kit, a
listed chimney−lining system, or a Type−B common vent.
Inspections before the sale and at the time of installation will
determine the acceptability of the chimney or the need for
repair and/or (re)lining. Refer to the Figure 27 to perform a
chimney inspection. If the inspection of a previously used
tile−lined chimney:
a. Shows signs of vent gas condensation, the chimney
should be relined in accordance with local codes and
the authority having jurisdiction. The chimney should
be relined with a listed metal liner, Type−B vent, or a
listed chimney adapter kit shall be used to reduce con-
densation. If a condensate drain is required by local
code, refer to the NFGC NFPA 54/ANSI Z223.1−2012,
Section 12.10 for additional information on condens-
ate drains.
b. Indicates the chimney exceeds the maximum per-
missible size in the tables, the chimney should be re-
built or relined to conform to the requirements of the
equipment being installed and the authority having jur-
isdiction.
A chimney without a clay tile liner, which is otherwise in good
condition, shall be rebuilt to conform to ANSI/NFPA 211 or be
lined with a UL listed metal liner or UL listed Type−B vent.
Relining with a listed metal liner or Type−B vent is considered
to be a vent−in−a−chase.
If a metal liner or Type−B vent is used to line a chimney, no
other appliance shall be vented into the annular space
between the chimney and the metal liner.
Exterior Masonry Chimney FAN + NAT
Installations with Type−B Double Wall Vent
Connectors {NFPA & AGA
Table 8 – Combined Appliance Maximum Input Rating in
Thousands of BTUH per Hour
INTERNAL AREA OF CHIMNEY
VENT HEIGHT
FT. (M)
12
(7741)
6 (1.8) 74
8 (2.4) 80
10 (3.0) 84
15 (4.5) NR
20 (6.0) NR
30 (9.1) NR
Table 9 – Minimum Allowable Input Rating of Space−
Heating Appliance in Thousands of BTUH per Hour
INTERNAL AREA OF CHIMNEY
VENT HEIGHT
12
FT (M)
(7741)
Local 99% Winter Design
Temperature: 17 to 26_F (-8 to -3_C)
6 (1.8) 0
8 (2.4) 52
10 (3.0) NR
15 (4.6) NR
20 (6.1) NR
30 (9.1) NR
Local 99% Winter Design
Temperature: 5 to 16_F* (-15 to -9_C)
6 (1.8) NR
8 (2.4) NR
10 (3.0) NR
15 (4.6) NR
24
2 2
IN (MM )
19 28 38
(12258) (18064) (24516)
119 178 257
130 193 279
138 207 299
152 233 334
NR 250 368
NR NR 404
2 2
IN . (MM )
19 28 38
(12258) (18064) (24516)
55 99 141
74 111 154
90 125 169
NR 167 212
NR 212 258
NR NR 362
78 121 166
94 135 182
111 149 198
NR 193 247
Specifications are subject to change without notice.
20 (6.1) NR
30 (9.1) NR
Local 99% Winter Design
Temperature: -10 to 4_F* (-23 to -16_C)
6 (1.8) NR
8 (2.4) NR
10 (3.0) NR
15 (4.6) NR
20 (6.1) NR
30 (9.1) NR
Local 99% Winter Design
Temperature: -11_F (-24_C) or lower
Not recommended for any vent configuration.
*The 99.6% heating db temperatures found in the 1997 or 2001 ASHRAE
Fundamentals Handbook, Climatic Design Information chapter, Table 1A (Un-
ited States) or the 2005 ASHRAE Fundamentals handbook, Climatic Design
Information chapter, and the CD−ROM included with the 2005 ASHRAE Fun-
damentals Handbook.
APPLIANCE APPLICATION REQUIREMENTS
Appliance operation has a significant impact on the
performance of the venting system. If the appliances are
sized, installed, adjusted, and operated properly, the venting
system and/or the appliances should not suffer from
condensation and corrosion. The venting system and all
appliances shall be installed in accordance with applicable
listings, standards, and codes.
The furnace should be sized to provide 100 percent of the
design heating load requirement plus any margin that occurs
because of furnace model size capacity increments. Heating
load estimates can be made using approved methods
available from Air Conditioning Contractors of America
(Manual J); American Society of Heating, Refrigerating, and
Air−Conditioning Engineers; or other approved engineering
methods. Excessive oversizing of the furnace could cause
the furnace and/or vent to fail prematurely. When a metal vent
or metal liner is used, the vent must be in good condition and
be installed in accordance with the vent manufacturer's
instructions.
To prevent condensation in the furnace and vent system, the
following precautions must be observed:
1. The return−air temperature must be at least 60_F
(16_C)db except for brief periods of time during warm−
up from setback at no lower than 55_F (13_C) db or
during initial start−up from a standby condition.
2. Adjust the gas input rate per the installation instruc-
tions. Low gas input rate causes low vent gas temper-
atures, causing condensation and corrosion in the fur-
nace and/or venting system. Derating is permitted only
for altitudes above 2000 ft. (610 M).
3. Adjust the air temperature rise to the midpoint of the
rise range or slightly above. Low air temperature rise
can cause low vent gas temperature and potential for
condensation problems.
4. Set the thermostat heat anticipator or cycle rate to re-
duce short cycling.
Air for combustion must not be contaminated by halogen
compounds which include chlorides, fluorides, bromides, and
iodides. These compounds are found in many common home
products such as detergent, paint, glue, aerosol spray,
bleach, cleaning solvent, salt, and air freshener, and can
cause corrosion of furnaces and vents. Avoid using such
products in the combustion−air supply. Furnace use during
construction of the building could cause the furnace to be
exposed to halogen compounds, causing premature failure of
the furnace or venting system due to corrosion.
Vent dampers on any appliance connected to the common
vent can cause condensation and corrosion in the venting
system. Do not use vent dampers on appliances common
vented with this furnace.
ADDITIONAL VENTING REQUIREMENTS
A 4" (101 mm) round vent elbow is supplied with the furnace.
A 5−inch (127 mm) or 6− inch (152 mm) vent connector may
NR NR 293
NR NR 377
NR 145 196
NR 159 213
NR 175 231
NR NR 283
NR NR 333
NR NR NR
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