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Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking com
-
bustion. Table 10 shows acceptable combustion for ALL
EL280UH models.
The maximum carbon monoxide
reading should not exceed 100 ppm
TABLE 10
Firing Rate
CO
2
% Nat
CO
2
% LP
High Fire
6.0 - 7.5
7.0 - 8.5
Low Fire
5.0 - 6.5
5.8 - 7.3
High Altitude
The manifold pressure may require adjustment and com-
bustion air pressure switch may need replacing to ensure
proper combustion at higher altitudes. Refer to table 11
for manifold pressure and table 12 for pressure switch
change and gas conversion kits.
TABLE 11
Manifold Pressure Settings
Unit
Input
Gas
Manifold Pressure in.
wg. 0 - 4500 ft
Manifold Pressure in.
wg. 4500 - 7500 ft
Manifold Pressure in. wg.
7500 - 10,000 ft
2
Supply Line
Pressure
in. w.g.
Low Firer
High Fire
Low Fire
High Fire
Low Fire
High Fire
Min
Max
070
Natural
1.7
3.5
1.6
3.4
1.7
3.5
4.5
13.0
LP/propane
3
4.9
10.0
4.9
10.0
4.9
10.5
11.0
13.0
090
Natuarl
1.7
3.5
1.5
3.2
1.7
3.5
4.5
13.0
LP/propane
3
4.9
10.0
4.9
10.0
4.9
10.0
11.0
13.0
110
Natural
1.7
3.5
1.5
2.8
1.7
3.5
4.5
13.0
LP/propane
3
4.9
10.0
4.9
10.0
4.9
10.0
11.0
13.0
135
Natural
1.7
3.5
1.5
2.8
1.7
3.5
4.5
13.0
LP/propane
3
4.9
10.0
4.9
10.0
4.9
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 12
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
070
No Change
91W53
73W35
73W37
11K51
11K46
77W09
090
91W53
73W35
110
91W53
73W35
135
73W33
73W34
NOTE - A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruc-
tion for the conversion procedure.
