Lennox EL280UHE Series - Page 27

Page 27
G- Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas ow rate before checking com-
bustion. See sections E- and F-. Take combustion sample
beyond the ue outlet. Table 13 shows acceptable com-
bustion for ALL EL280UHE(X) models. The maximum car-
bon monoxide reading should not exceed 100 ppm.
TABLE 13
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
H- 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 14
for manifold pressure and table 15 for pressure switch
change and gas conversion kits.
TABLE 14
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
045
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
070
Natural 1.7 3.5 1.6 3.4 1.7 3.5 4.5 13.0
LP/propane
3
4.5 10.0 4.5 10.0 4.5 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
4.5 10.0 4.5 10.0 4.5 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
4.5 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 orice 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 modications.
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
045
No Change
91W53 73W35
73W37 11K51 11K46 77W09
070 91W53 73W35
090 91W53 73W35
110 91W53 73W35
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.