Lennox International Inc. GWB9-075IH-2 Manuel D’Utilisation

Altitude in Ft.

0-5,000

5,000-10,000

Normal Input (MBH)

50

–

–

–

–

–

Manifold Pressure In W.C.

2.5

4

4

3.5

2.5

2.5

Orifi ce

43331094

43331094

Altitude in Ft.

0-5,000

5,000-10,000

Normal Input (MBH)

75

–

–

–

–

–

Manifold Pressure In W.C.

2.5

3.5

3.5

2.5

2.5

2.5

Orifi ce

43331092

43331092

Altitude in Ft.

0-5,000

5,000-10,000

Normal Input (MBH)

100

–

–

–

–

–

Manifold Pressure In W.C.

2.5

3.5

3.5

2.5

2.5

2.5

Orifi ce

43331090

43331090

• Boilers (with exception of 90-75 propane (LP) product) 

are factory equipped for operation at altitudes ranging 

from 0-10,000 feet above sea level. 

• No changes to factory settings are required for installa-

tions from 0-5,000 feet above sea level. 

• For altitudes from 5,000-10,000 feet above sea level 

gas manifold pressure needs to be adjusted based upon 

calorifi c (Btu) value of supply gas (contact local gas 

utility or distributor for this value). 

• For specifi c settings refer to  Table 2  for natural gas 

applications and  Table 3, Page 7  for propane (LP) gas 

applications. 

• Instructions on how to adjust gas manifold pressure 

settings see  Figure 27  and  Figure 28, Page 44 .

Note 90-75 propane (LP) applications for 5,000 - 10,000 

feet above sea level require orifi ce change as well as gas 

manifold pressure adjustment based upon calorifi c (Btu) 

value of supply gas. 
Refer to  Table 2   and  Table 3  for high altitude orifi ce part 

number. For replacing orifi ce refer to specifi c instructions 

included with conversion kit.