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F- Proper Gas Flow (Approximate)
Furnace should operate at least 5 minutes before check
ing gas flow. Determine time in seconds for two revolu
tions of gas through the meter. (Two revolutions assures a
more accurate time.) Divide by two and compare to time
in table 12 below. If manifold pressure matches table 12
and rate is incorrect, check gas orifices for proper size and
restriction.
NOTE- To obtain accurate reading, shut off all other gas
appliances connected to meter.
TABLE 12
GAS METER CLOCKING CHART
EL280DFE
Unit
Seconds for One Revolution
Natural LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
DIAL
-70 55 110 136 272
-90 41 82 102 204
Natural-1000 btu/cu ft LP-2500 btu/cu ft
IMPORTANT
For safety, shut unit off and remove manometer as
soon as an accurate reading has been obtained.
Take care to replace pressure tap plug.
G- Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking com
bustion. See sections E- and F-. Take combustion sample
beyond the flue outlet and compare to the table below. The
maximum carbon monoxide reading should not exceed
100 ppm.
TABLE 13
Firing Rate
CO
2
%
For
Nat
CO
2
%
For
L.P.
High Fire 6.0 - 7.5 7.0 - 8.5
Low Fire 5.0 - 6.5 5.8 - 7.3
The carbon monoxide reading should not exceed 100 ppm.
H-High Altitude
The manifold pressure, gas orifice and pressure switch
may require adjustment or replacement to ensure proper
operation at higher altitudes. See table 14 for manifold
pressures and table 15 for pressure switch kits and gas
conversion kits.
TABLE 14
Manifold Pressure Settings at all Altitudes
Unit
Input
Gas
Manifold
Pressure in.wg.
0-4500 ft.
Manifold
Pressure in.wg.
4501-7500 ft.
1
Manifold
Pressure in.wg.
7501 - 10,000 ft.
2
Supply Line
Pressure
in. w.g.
Low Fire High Fire Low Fire High Fire Low Fire High Fire Min Max
070
Natural 1.7 3.5 1.5 3.2 1.7 3.5 4.5 13.0
LP/propane
3
4.5 10.0 4.5 10.0 4.5 10.0 11.0 13.0
090
Natural 1.7 3.5 1.5 3.0 1.7 3.5 4.5 13.0
LP/propane
3
4.5 10.0 4.5 10.0 4.5 10.0 11.0 13.0
1
This is the only permissible derate for these units.
2
Natural gas high altitude orifice kit required.
3
A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion
procedure.
NOTE - Units may be installed at altitudes up to 4500 ft. above sea level without modifications.
TABLE 15
Pressure Switch and Gas Conversion Kits at all Altitudes
Unit
Input
High Altitude Pressure Switch Kit
High Altitude
Natural Gas Kit
LP/Propane Gas Kit
LP/Propane to
Natural Kit
0 - 4500 ft. 4501 - 7500 ft. 7501 - 10,000 ft. 7501 - 10,000 ft. 0 - 7500 ft 7501 - 10,000 ft. 0 - 7500 ft.Min
070
No Change No Change
73W36
73W37 11K51 11K46 77W09
090 73W36
NOTE - A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion
procedure.
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