Lennox International Inc EL280DF installation instructions Proper Combustion, High Altitude

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
Low Fire	4.2 − 5.7	5.0 − 6.0

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

		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
		Low Fire	High Fire	Low Fire	High Fire	Low Fire	High Fire	Min	Max
	Natural	1.7	3.5	1.5	3.2	1.7	3.5	4.5	13.0
070
	LP/propane3	4.9	10.0	4.9	10.0	4.9	10.0	11.0	13.0
	Natural	1.7	3.5	1.5	3.0	1.7	3.5	4.5	13.0
090
	LP/propane3	4.9	10.0	4.9	10.0	4.9	10.0	11.0	13.0
	Natural	1.7	3.5	1.5	3.2	1.7	3.5	4.5	13.0
110
	LP/propane3	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 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
Input
	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
070			73W36
090	No Change	No Change	73W36	73W37	77W07	77W11	77W09
110			73W35

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.

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