High altitude air pressure switch, Changing orifices, Tablp 6 natural gas manifold pressure (" w.c.) – Sears N8MPL050B12B1 User Manual
Page 29
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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.
441 01 2613 02
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