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High Altitude Derate (U.S. Installations Only)
When this furnace is installed at altitudes above 2,000
feet above sea level the furnace input must be derated 4
percent for each 1,000 feet above sea level because the
density of the air is reduced.
In some areas the gas supplier will derate the gas at a rate
of 4% for each 1,000 feet above sea level. It this is not
done, smaller orifices will be required at altitudes above
3,500 feet (nonderated natural gas) or 4,500 feet
(nonderated propane gas).
A different pressure switch is required at altitudes more
than 4,000 feet above sea level. This is required regard-
less of the heat content of the fuel used.
High altitude kits are purchased according to the altitude
and usage of either propane gas or natural gas. Refer to
the Amana distributor for required high altitude kit(s).
Do not derate the furnace by adjusting the manifold
pressure to a lower pressure than specified on the
furnace nameplate. With a lower air density and a lower
manifold pressure at the burner orifice, the orifice will not
supply the proper amount of air into the burner, causing
incomplete combustion of the gas, flashback, and pos-
sible yellow tipping.
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