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Page 53
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
Unit
Input
Gas
Orifice Size
0 − 7500 ft.
Orifice Size
7501 −
10,000 ft.
1
Manifold
Pressure in.wg.
0−4500 ft.
Manifold
Pressure in.wg.
4501−7500 ft.
Manifold
Pressure in.wg.
7501 − 10,000 ft.
2
Supply Line
Pressure
in. w.g.
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Min Max
070
Natural .063 .055 1.7 3.5 1.6 3.4 1.7 3.5 4.5 13.0
LP/propane
3
.039 .037 4.9 10.0 4.9 10.0 4.9 10.0 11.0 13.0
090
Natural .063 .055 1.7 3.5 1.5 3.2 1.7 3.5 4.5 13.0
LP/propane
3
.039 .037 4.9 10.0 4.9 10.0 4.9 10.0 11.0 13.0
110
Natural .063 .055 1.7 3.5 1.5 3.2 1.7 3.5 4.5 13.0
LP/propane
3
.039 .037 4.9 10.0 4.9 10.0 4.9 10.0 11.0 13.0
135
Natural .063 .055 1.7 3.5 1.6 2.8 1.7 3.5 4.5 13.0
LP/propane
3
.039 .037 4.9 10.0 4.9 10.0 4.9 10.0 11.0 13.0
1
This is the only permissible derate for these units.
2
Natural gas high altitude orifice kit required.
3
A 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
Unit
Input
High Altitude
Pressure Switch Kit
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
Unit
Input
High Altitude
Natural Gas
Orifice Kit
Natural Gas to
LP/ Propane Kit
LP/Propane
to
Natural Gas
Kit
7501 −
10,000 ft.
0 − 7500 ft.
7501 −
10,000 ft.
0 − 7500 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
Unit
Input
High Altitude
Natural Gas
Orifice Kit
Natural Gas to
LP/ Propane Kit
LP/Propane
to
Natural Gas
Kit
7501 −
10,000 ft.
0 − 7500 ft.
7501 −
10,000 ft.
0 − 7500 ft.
070 77W05 77W07 77W11 77W09
090 77W05 77W07 77W11 77W09
110 77W05 77W07 77W11 77W09
135 77W05 77W07 77W11 77W09