Carrier 58ST - Page 29

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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 s ystem 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 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 instructions.
Low gas input rate causes low vent gas temperatures,
causing condensation and corrosion in the furnace and/or
venting system. Derating is permitted only for altitudes
above 2000 ft..
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 thermostat heat anticipator or cycle rate to reduce short
cycling.
EXTERIOR MASONRY CHIMNEY FAN + NAT
INSTALLATIONS WITH TYPE--B DOUBLE--WALL
VENT CONNECTORS
TABLE A–COMBINED APPLIANCE MAXIMUM INPUT
RATING IN THOUSANDS OF BTUH PER HOUR
VENT
HEIGHT
(FT.)
INTERNAL AREA OF CHIMNEY
(SQ. IN.)
12 19 28 38
6 74 119 178 257
8 80 130 193 279
10 84 138 207 299
15 NR 152 233 334
20 NR NR 250 368
30 NR NR NR 404
TABLE B–MINIMUM ALLOWABLE INPUT RATING OF
SPACE--HEATING APPLIANCE IN THOUSANDS OF
BUT PER HOUR
VENT
HEIGHT
(FT.)
INTERNAL AREA OF CHIMNEY
(SQ. IN.)
12 19 28 38
Local 99% Winter Design
Temperature: 17 to 26 degrees F*
6 0 55 99 141
8 52 74 111 154
10 NR 90 125 169
15 NR NR 167 212
20 NR NR 212 258
30 NR NR NR 362
Local 99% Winter Design
Temperature: 5 to 16 degrees F*
6 NR 78 121 166
8 NR 794 135 182
10 NR 111 149 198
15 NR NR 193 247
20 NR NR NR 293
30 NR NR NR 377
Local 99% Winter Design
Temperature: --- 10 to 4 degrees F*
6 NR NR 145 196
8 NR NR 159 213
10 NR NR 175 231
15 NR NR NR 283
20 NR NR NR 333
30 NR NR NR NR
Local 99% Winter Design
Temperature: --- 11 degrees F or lower
*
Not recommended for any vent configuration
* The 99% Winter Design Dry ---Bulb (db) temperatures are found in the
1993 ASHRAE Fundamental s Handbook, chapter 24 , Table 1 (United
States) and 2 (Canada), or use the 99.6% heating db temperatures
foun d in the 1997 or 2001 ASHRAE Fundamentals Handbook, Climatic
Design Information chapter, Table 1A (United States) and 2A (Canada).
A04127
Fig. 28 --- Using Tin Snips to Cut Tie Points
58ST