Proper Combustion
Furnace should operate minimum 15 minutes with correct manifold pressure and gas flow rate before checking com- bustion. Table 12 shows acceptable combustion for ALL EL280DF models. The maximum carbon monoxide reading should not exceed 50 ppm
TABLE 12
Firing Rate | CO2% For Nat | CO2% For L.P. |
High Fire | 6.8 − 7.4 | 7.5 − 9.0 |
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Low Fire | 4.2 − 5.7 | 5.0 − 6.0 |
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High Altitude
The manifold pressure may require adjustment and com- bustion air pressure switch may need replacing to ensure proper combustion at higher altitudes. Refer to table 13 for
manifold pressure and table 14 for pressure switch change and gas conversion kits.
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 13
Manifold Pressure Settings at all Altitudes
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| Manifold | Manifold | Manifold | Supply Line | |||||
Unit | Gas | Pressure in.wg. | Pressure in.wg. | Pressure in.wg. | Pressure | |||||
0−4500 ft. | 4501−7500 ft.1 | 7501 − 10,000 ft.2 | in. w.g. | |||||||
Input | ||||||||||
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| Low Fire | High Fire | Low Fire | High Fire | Low Fire | High Fire | Min | Max | |
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| Natural | 1.7 | 3.5 | 1.5 | 3.2 | 1.7 | 3.5 | 4.5 | 13.0 | |
070 |
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LP/propane3 | 4.9 | 10.0 | 4.9 | 10.0 | 4.9 | 10.0 | 11.0 | 13.0 | ||
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| Natural | 1.7 | 3.5 | 1.5 | 3.0 | 1.7 | 3.5 | 4.5 | 13.0 | |
090 |
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LP/propane3 | 4.9 | 10.0 | 4.9 | 10.0 | 4.9 | 10.0 | 11.0 | 13.0 | ||
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| Natural | 1.7 | 3.5 | 1.5 | 3.2 | 1.7 | 3.5 | 4.5 | 13.0 | |
110 |
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LP/propane3 | 4.9 | 10.0 | 4.9 | 10.0 | 4.9 | 10.0 | 11.0 | 13.0 | ||
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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 14
Pressure Switch and Gas Conversion Kits at all Altitudes
| High Altitude Pressure Switch Kit | High Altitude | LP/Propane Gas Kit | LP/Propane to | ||||
Unit | Natural Gas Kit | Natural Kit | ||||||
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Input |
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0 − 4500 ft. | 4501 − 7500 ft. | 7501 − 10,000 ft. | 7501 − 10,000 ft. | 0 − 7500 ft | 7501 − 10,000 ft. | 0 − 7500 ft.Min | ||
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070 |
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| 73W36 |
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090 | No Change | No Change | 73W36 | 73W37 | 77W07 | 77W11 | 77W09 | |
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110 |
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| 73W35 |
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NOTE − 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.
Page 26