Amana AIR COMMAND 80 Manual page 7

Tqe sketch below shows how the filter is retained over the bot-
tom return air opening.
FILTER RETAINER
FILTER
FURNACE BOTTOM
Furnace models GU1070B40B, GU1090B50B, GU1115B50B and
GUI140B50B are shipped with two filters (refer to Pg. 2 for size).
If these furnaces are to be operated at high speed, then two
return air connections must be made. These may be made on
both sides of the furnace cabinet, or on one side and the bot-
tom. If one of the returns is connected to the bottom, refer to the
chart above for proper filter size. Failure to have two return air
connections, when these furnaces are operated on high speed
can result in insufficient airflow for air conditioning require-
ments and excessive air velocity through the filter. If these fur-
naces will not be run on high speed, one return air connection
will be adequate.
Guide dimples locate the bottom or side cutouts. Use a straight
edge to scribe lines connecting the dimples. Cut out the open-
ing on these lines. For bottom return air connection the bottom
of the cabinet has to be removed before the furnace is posi-
tioned on the raised platform or set on top of the return air duct.
It is a must that a closed return duct system be used, with the
return duct connected to the furnace. Supply and return duct
connections to the unit may be made with flexible joints to mini-
mize noise transmission. If a central return is used, a connec-
ting duct must be installed between the unit and the utility room
wall so the furnace blower will not interfere with combustion air
or draft. The room, closet or alcove must not be used as a
return air chamber.
When the furnace is used in connection with a cooling unit the
furnace should be installed in parallel with or on the upstream
side of the cooling unit to avoid condensation in the heating
element. With a parallel flow arrangement, the dampers or
other means used to control the flow of air should be adequate
to prevent chilled air from entering the furnace and if manually
operated, must be equipped with means to prevent operation of
either unit unless the damper is in the full heat or cool position.
GAS SUPPLY AND PIPING
The rating plate is stamped with the model number, type of
gas and gas input rating. Make sure the furnace is equipped
to operate on the type of gas available.
GAS TYPE
SUPPLY PRESSURE
MAX MIN
Natural
Propane
10.0"
14.0"
5.0"
11.0"
Inlet gas pressure must not exceed the maximum value
shown in table above.
The minimum supply pressure should not be varied down-
ward because this could decrease the heating capacity of the
furnace. Gas input to the burners should not exceed the rated
input shown on the rating plate.
HIGH ALTITUDE DEBATE
When this furnace is installed at altitudes above 2000 feet,
the furnace input must be derated 4% for each 1000 feet
above sea level because the density of the air is reduced.
In some areas the gas supplier will derate the heating value
of the gas at a rate of 4% for each 1000 feet above sea level.
If he does not do so, smaller orifices will be required at
altitudes above 3500 feet (non-derated natural gas) or 4500
feet (non-derated propane).
A different pressure switch will be required at altitudes more
than 4000 feet above sea level. This is required regardless of
the heat content of the fuel used.
High altitude kits can be purchased depending upon the
altitude and usage of propane or natural gas.
Adjustment of the manifold pressure to a lower pressure
reading than what is specified on the furnace nameplate is
not a proper derate procedure. With a lower density of air and
a lower manifold pressure at the burner orifice, the orifice will
not aspirate the proper amount of air into the burner. This can
cause incomplete combustion of the gas, flash back, and
possible yellow tipping.
GAS PIPING
®
CAUTION
To avoid possible unsatisfactory opera-
tion or equipment damage due to under-
firing of equipment, do not undersize the
natural gas/propane piping from the
meter/tank to the furnace. When sizing
per the tables, include all appliances that
could be operated simultaneously.
The gas pipe supplying the furnace must be properly sized
based on the cubic feet per hour of gas flow required, specific
gravity of the gas and length of the run. The gas line installa-
tion must comply with local codes, or in the absence of local
codes, with the latest edition of the National Fuel Gas Code
ANSI Z223.1.
NATURAL GAS CAPACITY OF PIPE
IN CUBIC FEET OF GAS PER HOUR (CFH)
Length of
Pipe in Feet
Nominal Black Pipe Size
'/2 " 3/4 "
1"
1'/4"
1'/2 "
10 132 278 520 1,050 1,600
20 92 190 350
730 1,100
30 73
152 285 590 980
40 63 130 245 500 760
50 56 115 215 440 670
60 50 105 195 400 610
70 46 96
180
370
560
80 43 90 170 350 530
90 40 84 160 320 490
100 38 79 150 305 460
CONNECTING THE GAS PIPING - NATURAL GAS
Refer to Figure 6 for the general layout at the furnace. The
following rules apply:
1. Use black iron or steel pipe and fittings for the building
piping.
2. Use pipe joint compound on male threads only. Pipe joint
compound must be resistant to the action of the fuel used.
3. Use ground joint unions.
4. Install a drip leg to trap dirt and moisture before it can
enter the gas valve. The drip leg must be a minimum of
three inches long.
5. Use two pipe wrenches when making connection to the
gas valve to keep it from turning.
6. Install a manual shut-off valve.
7. Tighten all joints securely.
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