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31-5000726 Rev. 0
Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the flue
outlet and compare to Table 14.
The maximum carbon
monoxide reading should not exceed 100 ppm.
Model
CO
2
% for Nat
CO
2
% for LP
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
-135
6.1 - 7.1
7.8 - 8.8
7.1 - 8.2
9.1 - 10.1
The maximum carbon monoxide reading should not exceed
100ppm.
Table 14.
High Altitude
The manifold pressure, gas orifice and pressure switch
may require adjustment or replacement to ensure proper
operation at higher altitudes. See Table 15 for manifold
pressures. See Table 16 for gas conversion and pressure
switch kits.
NF96UV
Gas
Manifold Pressure in w.g.
Supply Line
Pressure in
w.g.
0 - 10000 ft.
0 - 4500 ft.
4501 - 5500 ft.
5501 - 6500ft.
6501 - 7500ft.
7501-10000ft.
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Min.
Max.
All Models
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 15.
Manifold and Supply Line Pressure 0 - 10,000 ft.
Model
Natural to LP/
Propane
High Altitude Natural
Burner Orifice Kit
High Altitude LP/
Propane Burner
Orifice Kit
High Altitude Pressure switch
0 - 7500 ft
(0 - 2286m)
7501 - 10000 ft
(2286 - 3048m)
7501 - 10000 ft
(2286 - 3048m)
4501 - 7500 ft
(1371 - 2286m)
7501 - 10000 ft
(2286 - 3048m)
045
11K48
*51W01
11K47
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-
1371 m).
Table 16.
Conversion Kit Fan Pressure Switch Requirements at Varying Altitudes
