| MANIFOLD | HIGH FIRE ADJUSTMENT |
INLET PRESSURE POST | SCREW | |
| PRESSURE TAP | (under cap) |
GAS VALVE SHOWN IN ON POSITION | ||
FIGURE 22
8 − Move switch on gas valve to ON. Do not force. See fig- ure 22.
9 − Replace the upper access panel.
10− Turn on all electrical power to to the unit. 11− Set the thermostat to desired setting.
NOTE − When unit is initially started, steps 1 through 11 may need to be repeated to purge air from gas line.
12− If the appliance will not operate, follow the instructions urning Off Gas to Unit" and call your service techni- cian or gas supplier.
Turning Off Gas to Unit
1 − Set the thermostat to the lowest setting.
2 − Turn off all electrical power to the unit if service is to be performed.
3 − Remove the upper access panel.
4 − Move switch on gas valve to OFF. Do not force.
5 − Replace the upper access panel. Failure To Operate
If the unit fails to operate, check the following:
1 − Is the thermostat calling for heat?
2 − Are access panels securely in place?
3 − Is the main disconnect switch closed?
4 − Is there a blown fuse or tripped circuit breaker?
5 − Is the filter dirty or plugged? Dirty or plugged filters will cause the limit control to shut the unit off.
6 − Is gas turned on at the meter?
7 − Is the manual main
8 − Is the internal manual
9 − Is the unit ignition system in lock out? If the unit locks out again, call the service technician to inspect the unit for blockages.
10 − Is pressure switch closed? Obstructed flue will cause unit to shut off at pressure switch. Check flue and outlet for blockages.
11 − Are flame rollout switches tripped? If flame rollout switches are tripped, call the service technician for in- spection.
Gas Pressure Adjustment
Gas Flow (Approximate)
TABLE 11
GAS METER CLOCKING CHART
| Seconds for One Revolution | |||||
|
|
|
|
|
|
|
EL280DF | Natural |
| LP |
| ||
Unit | 1 cu ft | 2 cu ft |
| 1 cu ft |
| 2 cu ft |
| Dial | Dial |
| Dial |
| DIAL |
|
|
|
|
|
|
|
−045 | 80 | 160 |
| 200 |
| 400 |
|
|
|
|
|
|
|
−070 | 55 | 110 |
| 136 |
| 272 |
|
|
|
|
|
|
|
−090 | 41 | 82 |
| 102 |
| 204 |
|
|
|
|
|
|
|
−110 | 33 | 66 |
| 82 |
| 164 |
|
|
|
|
|
|
|
−135 | 27 | 54 |
| 68 |
| 136 |
|
|
|
|
|
|
|
Natural−1000 btu/cu ft | LP−2500 btu/cu ft |
| ||||
Furnace should operate at least 5 minutes before check- ing gas flow. Determine time in seconds for two revolu- tions of gas through the meter. (Two revolutions assures a more accurate time.) Divide by two and compare to time in table 11. If manifold pressure matches table 13 and rate is incorrect, check gas orifices for proper size and restric- tion. Remove temporary gas meter if installed.
NOTE − To obtain accurate reading, shut off all other gas appliances connected to meter.
Supply Pressure Measurement
An inlet post located on the gas valve provides access to the supply pressure. See figure 22. Back out the 3/32 hex screw one turn, connect a piece of 5/16 tubing and connect to a manometer to measure supply pressure. See table 13 for supply line pressure.
Manifold Pressure
NOTE − Pressure test adapter kit (10L34) is available from Lennox to facilitate manifold pressure measurement.
1 − Connect test gauge to manifold pressure tap (figure 22) gas valve.
2 − Ignite unit on high fire and let run for 5 minutes to allow for steady state conditions.
3 − After allowing unit to stabilize for 5 minutes, record manifold pressure and compare to value given in table 13.
4 − If necessary, make adjustments. Figure 22 shows location of high fire adjustment screw.
5 − If an adjustment is made on high fire, re−check man- ifold pressure on low fire. Do not adjust low fire man- ifold pressure. If low fire manifold pressure is more than 1/2" above or below value specified in table 13, replace valve.
NOTE − Shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to remove barbed fitting and replace threaded plug.
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