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Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas ow rate before checking com-
bustion. Take combustion sample beyond the ue outlet
and compare to the tables below.
TABLE 14
ML296
Model
CO
2
% For Nat CO
2
% For L.P
Low Fire High Fire Low Fire High Fire
045 5.4 - 6.4 7.5 - 8.5 6.4 - 7.4 8.8 - 9.8
070 5.3 - 6.3 7.4 - 8.4 6.3 - 7.3 8.7 - 9.7
090 5.8 - 6.8 7.6 - 8.6 6.8 - 7.8 8.9 - 9.9
110 6.1 - 7.1 8.0 - 9.0 7.1 - 8.1 9.3 - 10.3
The maximum carbon monoxide reading should not exceed 100ppm.
High Altitude Information
NOTE - In Canada, certication for installations at eleva-
tions over 4500 feet (1372 m) is the jurisdiction of local
authorities.
Units may be installed at altitudes up to 10,000 ft. above
sea level. See table 15 for de-rate manifold values. Units
installed at altitude of 7501 - 10,000 feet require an orice
change. Units installed at altitude of 4501 - 10,000 feet
require a pressure switch change which can be ordered
separately. Table 16 lists conversion kit and pressure
switch requirements at varying altitudes.
The combustion air pressure switch is factory-set and re-
quires no adjustment.
TABLE 15
Manifold and Supply Line Pressure 0-10,000ft.
Unit Gas
Manifold Pressure in. wg. Supply Line
Pressure in. w.g
0 - 10,000 ft.
0 - 4500 ft 4501 - 5500 ft. 5501 - 6500 ft 6501 - 7500 ft 7501 - 10,000 ft
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Min Max
All
Sizes
Natural 1.7 3.5 1.6 3.3 1.5 3.2 1.5 3.1 1.7 3.5 4.5 13.0
LP/
Propane
4.9 10.0 4.6 9.4 4.4 9.1 4.3 8.9 4.9 10.0 11.0 13.0
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.
TABLE 16
LP/Propane Conversion Kit and Pressure Switch Requirements at Varying Altitudes
Unit
Natural to
LP/Propane
High Altitude
Natural Burner
Orice Kit
High Altitude LP/
Propane Burner
Orice Kit
High Altitude Pressure Switch
0 - 7500 ft 7501 - 10,000 ft 7501 - 10,000 ft 4501 - 7500 ft 7501 - 10,000 ft
045
*11K51 73W37 *11K46
14A47 14A50
070 14A54 14A53
090 14A57 14A54
110 14A46 14A51
135 14A49 14A51
* Conversion requires installation of a gas valve manifold spring which is provided with the gas conversion kit. Pressure switch is factory
set. No adjustment necessary. All models use the factory-installed pressure switch from 0-4500 feet (0-1370 m).