Model No.
0 to 4500 ft. (0 to 1372 m) above sea level
3.8
3.5 (0.87)
7.5
7.5(1.90)
7.511.90)
TABLE 6 |
|
|
| |
Manifold Pressure (outlet) in. w.g (kPa) |
| |||
4501 to 5500 ft. | 5501 to 6500 ft. | 6501 to 7500ft, | ||
(1373 to 1676 m) | (1677 to 1981 m) | (1982to2286 m) | ||
above sea level | above sea level | above sea level | ||
| 3,5 |
| 35 | 3.5 |
34(0.85) | 3.3 (0.82) | 3.2 (0.80) | ||
| 7.5 |
| 7.5 | 7.5 |
7.3 | (1.81) | 7.1 | (1.80) | 7.0 (1.74) |
7.3 (1.81 } | 7.1 (1.8o) | 7.0 (1.74) | ||
Manifold Pressure Measurement & Adjustment
NOTE - Pressure test adaptor kit (10L34) is available
from Lennox to facilitate manifold pressure measure- ment.
1 - Connect test gauge to outlet tap on gas valve.
2 - Disconnect pressure sensing hose from gas valve and plug hose by covering opening with tape or equivalent. Leave barbed fitting on valve open to at- mosphere. See figure 35 for differential pressure switch circuitry on 75 kBtuh models. Only 75 kBtuh models are equipped with a secondpressure switch. Other models have single pressure switch.
75 kBtuhDIFFERENTIALPRESSURESWITCHCIRCUITRY
| BURNER | |
| BOX | |
LOW HEAT |
| |
DIFFERENTIAL |
| |
PRESSURE | BARS | |
SWITCH |
| |
TEE | SOX | |
| SENSING | |
HIGH HEAT | HOSE | |
DIFFERENTIAL |
| |
PRESSURE | GAS | |
SWITCH | ||
VALVE | ||
| ||
COMBUSllON | SENSING | |
HOSE | ||
AIR PRESSURE | ||
| ||
SENSING HOSE |
| |
| GAS | |
| VALVE | |
COMBUSTION |
| |
AIR INOUCER | PRESSURE | |
HONEYWELL PPS | SWITCH | |
PRESSURE | SENSING | |
SWITCH | HOSE | |
SHOWN |
|
LEFT SIO_ OF PRESSURE SWITCH = MORE NEGATIVE
RIGH'rSIDE OF PRESSURE SWITCH = LESS NEGATIVE (Closer to Zero)
FIGURE 35
3 - Start uniton high heat and allow 5 minutes for unitto reach steady state.
4- While waiting for the unit to stabilize, notice the flame. Flame should be stable and should not lift
from burner. Natural gas shouldbum blue.
5 - After allowing unit to stabilize for 5 minutes, record manifold pressure and compare to value given in table 6.
NOTE - Shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to re- place pressure tap plug.
NOTE - During this test procedure, the unit will be overt/r- ing:
•Operate unit only long enough to obtain accurate read- ing to prevent overheating heat exchanger.
•Attempts to clock gas valve during this procedure will be inaccurate. Measure gas flow rate only during nor- mal unit operation.
6 - When test is complete remove obstruction from hose and return hose to gas valve barbed fitting.
Refer to table 6 for manifold pressuresettings for installa- tions at altitudes from 0 to 7500 feet (0 to 2286 m). NOTE - In Canada, certification for installations at eleva- tions over 4500 feet (1372 m) is thejurisdiction of local au- thorities.
The two pressure switches (high and low heat) are factory set and are not to be adjusted.
NOTE - Disconnect power to unit before making any adjustments.
Heat Anticipation Settings
Thermostat anticipator setting (if adjustable) should be set accordingto amps listed on widng diagram on unit. Flame Rollout Switch
Factory set: No adjustment necessary.
Limit Control
Factory set: No adjustment necessary.
Pressure Switches
Factory set: No adjustment is necessary. Fan Control
The
individual applications. See figure 36.
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