Proper Combustion; High Altitude - Lennox MERIT Series Installation Instructions Manual

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. The maximum carbon
monoxide reading should not exceed 100 ppm
TABLE 14
ML195 Unit
045
070
090
110
ML195
Gas
Unit
Natural
All
Models
L.P. Propane
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.
Conversion Kit and Pressure Switch Requirements at Varying Altitudes
ML195
Unit
-045
-070
-090
-110
* Conversion requires
Pressure switch is factory set. No adjustment necessary. All models use the factory-installed pressure switch from 0-4500 feet (0-1370 m).
Nat
CO CO
2 2
7.2 - 8.2 8.6 - 9.6
Manifold and Supply Line Pressure 0-10,000ft.
0 - 4500 ft 4501 - 5500 ft
3.5 3.3
10.0 9.4

High Altitude

LP/Propane
Natural
0 - 7500 ft 7501 - 10,000 ft
(0 - 2286m) (2286 - 3038m)
*11K49 73W37
installation of a gas valve
High Altitude Information
NOTE - In Canada, certification 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 orifice
change. Units installed at altitude of 4501 - 10,000 feet
LP
require a pressure switch change which can be ordered
separately.
Table 16 lists conversion kit and pressure switch require-
ments 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
necessary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.
TABLE 15
Manifold Pressure in. wg.
5501 - 6500 ft 6501 - 7500 ft 7501 - 10,000 ft
3.2
9.1
TABLE 16
High Altitide
LP/Propane
7501 - 10,000 ft
(2286 - 3038m)
*11K44
manifold spring which
Page 41
3.1 3.5
8.9 10.0
High Altitude Pressure Switch
4501 - 7500 ft
(1373 - 2286m)
No Change
11U71
11U70
11U71
is provided with the
Supply Line Pressure
in. w.g.
0 - 10000 ft.
4.5 13.0
11.0 13.0
7501 -10,000 ft
(2286 - 3048m)
11U65
11U64
11U64
11U64
gas conversion kit.