High Altitude

The manifold pressure, gas orifice and pressure switch may require adjustment or replacement to ensure proper operation at higher altitudes. Tables 22 through 25 shows

manifold pressure, pressures switch and gas conversion kits at all altitudes.

IMPORTANT

For safety, shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to replace pressure tap plug.

TABLE 22

Manifold Pressure Settings

 

 

 

 

Manifold

Manifold

Manifold

Supply Line

Unit

 

Orifice Size

Orifice Size

Pressure in.wg.

Pressure in.wg.

Pressure in.wg.

Pressure

Gas

7501 −

0−4500 ft.

4501−7500 ft.

7501 − 10,000 ft.2

in. w.g.

Input

0 − 7500 ft.

10,000 ft.1

 

 

 

 

 

 

 

 

 

Low

High

Low

High

Low

High

Min

Max

 

 

 

 

 

 

 

 

Fire

Fire

Fire

Fire

Fire

Fire

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Natural

.063

.055

1.7

3.5

1.6

3.4

1.7

3.5

4.5

13.0

070

 

 

 

 

 

 

 

 

 

 

 

LP/propane3

.039

.037

4.9

10.0

4.9

10.0

4.9

10.0

11.0

13.0

 

 

Natural

.063

.055

1.7

3.5

1.5

3.2

1.7

3.5

4.5

13.0

090

 

 

 

 

 

 

 

 

 

 

 

LP/propane3

.039

.037

4.9

10.0

4.9

10.0

4.9

10.0

11.0

13.0

 

 

Natural

.063

.055

1.7

3.5

1.5

3.2

1.7

3.5

4.5

13.0

110

 

 

 

 

 

 

 

 

 

 

 

LP/propane3

.039

.037

4.9

10.0

4.9

10.0

4.9

10.0

11.0

13.0

 

 

Natural

.063

.055

1.7

3.5

1.6

2.8

1.7

3.5

4.5

13.0

135

 

 

 

 

 

 

 

 

 

 

 

LP/propane3

.039

.037

4.9

10.0

4.9

10.0

4.9

10.0

11.0

13.0

 

1This is the only permissible derate for these units.

2Natural gas high altitude orifice kit required.

3A 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.

NOTE − Units may be installed at altitudes up to 4500 ft. above sea level without modifications.

TABLE 23

High Altitude Pressure Switch Kits

 

 

High Altitude

 

Unit

 

Pressure Switch Kit

Input

 

 

 

0 − 4500 ft.

4501 − 7500 ft.

7501 − 10,000 ft.

 

 

 

 

 

070

No Change

No Change

73W35

 

 

 

 

090

No Change

69W56

73W35

 

 

 

 

110

No Change

69W56

73W35

 

 

 

 

135

No Change

73W33

73W34

 

 

 

 

TABLE 24

Honeywell Gas Valve Conversion Kits

 

High Altitude

 

 

LP/Propane

 

Natural Gas to

to

 

Natural Gas

 

LP/ Propane Kit

Natural Gas

Unit

Orifice Kit

 

 

Kit

Input

 

 

 

 

 

 

 

 

7501 −

0 − 7500 ft.

7501 −

0 − 7500 ft.

 

10,000 ft.

10,000 ft.

 

 

 

 

 

 

 

 

070

73W37

51W02

73W38

69W79

 

 

 

 

 

090

73W37

51W02

73W38

69W79

 

 

 

 

 

110

73W37

51W02

73W38

69W79

 

 

 

 

 

135

73W37

51W02

73W38

69W79

 

 

 

 

 

TABLE 25

White Rodgers Gas Valve Conversion Kits

 

High Altitude

 

 

LP/Propane

 

Natural Gas to

to

 

Natural Gas

 

LP/ Propane Kit

Natural Gas

Unit

Orifice Kit

 

 

Kit

Input

 

 

 

 

 

 

 

 

7501 −

0 − 7500 ft.

7501 −

0 − 7500 ft.

 

10,000 ft.

10,000 ft.

 

 

 

 

 

 

 

 

070

77W05

77W07

77W11

77W09

 

 

 

 

 

090

77W05

77W07

77W11

77W09

 

 

 

 

 

110

77W05

77W07

77W11

77W09

 

 

 

 

 

135

77W05

77W07

77W11

77W09

 

 

 

 

 

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Lennox International Inc SL280UH070V36A, SL280UH090V48B, SL280UH090V36B installation instructions High Altitude