Sears N8MPL050B12B1 - Manual (Page 18)

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 fur­
nace.
8. Gas Supply and Piping
WARNING
CARBON MONOXIDE POISONING, FIRE AND
EXPLOSION HAZARD.
Failure to follow safety warnings exactly could
result in serious injury, death, and/or property
damage.
Models designated for Natural Gas are to be used
with Natural Gas ONLY, unless properly converted to
use with LP gas.
a.
b.
Gas Supply Requirements
Use only the Type of gas approved for this furnace. See rating
plate for approved gas type.
Gas input must not exceed the rated input shown on the rating
plate. Overfiring will result in failure of heat exchanger and
cause dangerous operation.
Do not allow minimum supply pressure to vary downward. Do­
ing so will decrease input to furnace. Refer to Table 3 for gas
supply. Refer to Table
6 and Table 7 for manifold pressures.
Gas Piping Requirements
NOTE: The gas supply line must be installed by a qualified service
technician in accordance with all building codes.
NOTE: In the state of Massachusetts.
Gas supply connections MUST be performed by a li­
censed plumber or gas fitter).
When flexible connectors are used, the maximum length
shall not exceed 36" (915 mm).
c. When lever handle type manual equipment shutoff
valves are used, they shall be T-handle valves.
d. The use of copper tubing for gas piping is NOT approved.
1. Install gas piping in accordance with local codes, or in the ab­
sence of local codes, the applicable national codes.
2. It is recommended that a manual equipment shutoff valve be
installed in the gas supply line outside the furnace. Locate
valve as close to the furnace as possible where it is readily ac­
cessible. Refer to Figure 12.
Table 3 Gas Pressures
Gas Type
Supply Pressure
Recommended Max. Min.
Natural 7" 14" 4.5"
Propane 11” 14” 11”
A WARNING
FIRE HAZARD
Failure to follow safety warnings exactly could
result in death or personal injury.
Use wrench to hold furnace gas control valve when
turning elbows and gas line to prevent damage to
the gas control valve and furnace.
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