Sears N8MPN075F16B1 I! i! i I! i! i! i! i, Changing Orifices, High Altitude Air Pressure Switch

MANIFOLDPRESSUREAND ORIFICE SIZE FOR HIGHALTITUDEAPPLICATIONS

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												41	3.7	41	3.4
750												41	3.5	42	3.6
775										41	3.6	42	3,6	42	3.3
800							41		3.6	42	3.7	42	3.4	42	3.1
825					41	3.7	41		3.4	42	3,5	42	3,2	42	2.9
850					41	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	_i_i_i_i_iiiiiiiiiiiiiiiiiiiiiiiiiii i ; ;%;iiiiiiiiiiiiiiiiiil;i;! iiiiiiiiiiiiiiiiiiiiiii¸¸;i ;i;i;i;i;i;i;i;iiiiiiiiiiiiiiiiiii!; iiiiiiiiiiiiiiiiiiiiiiiiiiii!¸i¸;¸;¸;¸;¸;¸;¸;¸;¸;i!ii!iiiililililiiii!ii! i!ii!ii

NOTE: Natural gas data is based on 0.60 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.

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LPG or

PROPANE

GAS MANIFOLD

PRESSURE

HEATING

VALUE

MEAN

ELEVATION

FEET ABOVE

SEA LEVEL

at ALTITUDE

0 to

2001 to

3001 to

4001 to

5001 to

6001 to

7001 to

BTU/CU.

FT.

2000

3000

4000

5000

6000

7000

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/N FPA

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:

_

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Orifice

#41

1096942

Orifice

#42

1011351

Manifold

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.

Some Models may vary

25-25-00

5.Carefully remove the manifold assembly.

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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