Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking com
bustion. Take combustion sample beyond the flue outlet
and compare to the tables below.
TABLE 12
ML193
Unit
-045
-070
-090
-110
-135
The maximum carbon monoxide reading should not exceed 50 ppm.
Conversion Kit and Pressure Switch Requirements at Varying Altitudes
Natural to
LP/Propane
ML193
Unit
0 - 7500 ft
(0 - 2286m)
-045
-070
-090
*69W73
-110
-135
* 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).
CO
%
CO
%
2
For Nat
2
For L.P.
7.2 - 7.9
8.6 - 9.3
High Altitude
Natural Burner
Orifice Kit
7501 - 10,000 ft
(2286 - 3038m)
73W37
High Altitude Information
NOTE - In Canada, certification for installations at eleva
tions over 4500 feet (1372 m) is the jurisdiction of local au
thorities.
ML193UH units require no manifold pressure adjustments
for operation at altitudes up to 10,000 feet (3048 m) above
sea level. Units installed at altitude of 4501 - 10,000 feet
(1373 to 3048m) require a pressure switch change which
can be ordered separately. Table 13 lists conversion kit
and pressure switch requirements at varying altitudes.
The combustion air pressure switch is factory-set and re
quires no adjustment.
NOTE - A natural to LP/propane gas changeover kit is nec
essary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.
TABLE 13
LP/Propane
High Altitude
to
LP/Propane
Natural
Burner Orifice Kit
0 - 7500 ft
7501 - 10,000 ft
(0 - 2286m)
(2286 - 3038m)
*73W81
*68W68
Page 42
High Altitude Pressure Switch
4501 - 7500 ft
7501 -10,000 ft
(1373 - 2286m)
(2286 - 3048m)
93W87
93W88