Sears N8MPL050B12B1 - Manual (Page 29)

MANIFOLD PRESSURE AND ORIFICE SIZE FOR HIGH ALTITUDE APPLICATIONS
TablP 6
NATURAL GAS MANIFOLD PRESSURE (" w.c.)
MEAN ELEVATION FEET ABOVE SEA LEVEL
HEATING 0 to 2001 to 3001 to 4001 to 5001 to 6001 to 7001 to
VALUE 2000 3000 4000 5000 6000 7000 8000
at ALTITUDE Orifice Manifold Orifice Manifold Orifice Manifold Orifice Manifold Orifice Manifold Orifice Manifold Orifice Manifold
BTU/CU. FT. No. Pressure No. Pressure No. Pressure No. Pressure No. Pressure No. Pressure No. Pressure
700 41 3.7
725 1 ■ 3.7 41 3.4
750 1 ■ 3.5 42 3.6
775 -1 3.6 42 3.6 42 3.3
800 41 3.6 42 3.7 42 3.4 42 3.1
825 ■: 1 J. / 41 3.4 42 3.5 42 3.2 42 2.9
850 4| 3,5 42 3.6 42 3.3 42 3.0 42 2.8
875
:■
41 3.6 42 3.6 42 3.4 42 3.1 42 2.8 42 2.6
900 42 3.7 42 3,4 42 3.2 42 2.9 42 2.7 42 2.5
925 41 3.7 42 3.5 42 3.3 42 3.0 42 2.8 42 2.5 44 3.3
950 41 3.5 42 3.3 42 3.1 42 2.9 42 2.6 42 2.4 44 3.1
975 42 3.7 42 3.2 42 2.9 42 2.7 42 2.5 44 3.2 45 3.6
1000 42 3.5 42 3.0 42 2.8 42 2.6 42 2.4 45 3.7 45 3.4
1050 42 3.2 42 2.7 42 2.5 44 3.3 45 3.6 -- -- --
1100 43 3.6 42 2.5 44 3.2 45 3.6
NOTE; Natural gas data is based on 0.60 specific gravity.
Z223.1-2002/NFPA 54-2002 or National Standard of Canada,
For fuels with different specific gravity consult the National Fuel Gas Code ANSI
Natural Gas And Propane Installation Code CSA B149.1 -05.
Tcible 7 LPG or PROPANE GAS MANIFOLD PRESSURE (" w.c.)
HEATING VALUE
at ALTITUDE
BTU/CU. FT.
MEAN ELEVATION FEET ABOVE SEA LEVEL
0 to
2000
2001 to
3000
3001 to
4000
4001 to
5000
5001 to
6000
6001 to
7000
7001 to
8000
2500 10.0 10.0 9.0 10.0 9.4 8.5 10.0
Orifice Size #54 #54 #54 #55 #55 #55 #56
NOTE; Propane data is based on 1.53 specific gravity. For fuels with different specific gravity consult the National Fuel Gas Code ANSI Z223.1 -2002/NFPA
54-2002 or National Standard Of Canada, Natural Gas And Propane Installation Code CSA B149.1 -05.
NOTE: The derating of these furnaces at 2% (Natural Gas) and 4% (Propane Gas) has been tested and design-certified by CSA.
In Canada, the input rating must be derated 5% (Natural Gas) and 10% (Propane Gas) for altitudes of 2,000 to 4,500 above sea level. Use
the 2001 to 3000 column in Table 6 and Table 7.
The burner orifice part nos. are as follows:
Orifice #41
1096942 Orifice #42 1011351
Orifice #43 1011377 Orifice #44 1011352
Orifice #45 1011353 Orifice #54 1011376
Orifice #55 1011354 Orifice #56 1011355
High Altitude Air Pressure Switch
The factory-installed pressure switch need NOT be changed for
any furnace installations from sea level up to and including
8,000'
altitude
Changing Orifices
1. After disconnecting power and gas supply to the furnace, re­
move the burner compartment door, exposing the burner
compartment.
2. Disconnect gas line from gas valve so manifold can be re­
moved.
3. Disconnect wiring at gas valve. Be sure to note the proper
location of all electrical wiring before being disconnected.
4. Remove the four (4) screws holding the manifold and gas
valve to the manifold supports. Do not discard any screws.
See Figure 35._______________________________________
6. Remove the orifices from the manifold and replace them with
proper sized orifices. See Figure 36.
7. Tighten orifices so they are seated and gas-tight. See
Figure 36.
8. Reassemble all parts in reverse order as removed. Be sure to
engage the main burner orifices in the proper openings in the
burners.
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