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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 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 the thermostat heat anticipator or cycle rate to reduce short
cycling.
Air for combustion must not be contaminated by halogen com-
pounds 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" round vent elbow is supplied with the furnace. A 5-inch or 6-
inch vent connector may be required for some model furnaces. A
field-supplied 4-inch-to-5-inch or 4-inch-to-6-inch sheet metal
increaser fitting is required when 5-inch or 6-inch vent connector
is used. See Fig. 32–44 Venting Orientation for approved vent
configurations.
NOTE: Vent connector length for connector sizing starts at
furnace vent elbow. The 4-inch vent elbow is shipped for upflow
configuration and may be rotated for other positions. Remove the
3 screws that secure vent elbow to furnace, rotate furnace vent
elbow to position desired, reinstall screws. The factory-supplied
vent elbow does NOT count as part of the number of vent
connector elbows.
The vent connector can exit the door through one of 5 locations on
the door.
Fig. 27—Using Tin Snips to Cut Tie Points
26
Fig. 28—Rounded End of Knockout
Fig. 29—Knockout Pulled Loose
1. Attach the single wall vent connector to the furnace vent
elbow, and fasten the vent connector to the vent elbow with at
least two field-supplied, corrosion-resistant, sheet metal
screws located 180° apart.
NOTE: An accessory flue extension KGAFE0112UPH is avail-
able to extend from the furnace elbow to outside the furnace
casing. If flue extension is used, fasten the flue extension to the
vent elbow with at least two field-supplied, corrosion-resistant,
A04127
A04128
A04129
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