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Hersteller: Lennox International Inc. Dateigröße: 1.42 mb Dateiname: Unterrichtssprache:

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 atmosphere. 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 SENSING COMBUSllON 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'r SIDE 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. 35 3.5 3.3 (0.82) 7.5 7.1 (1.80) 7.1 (1.8o) 3.2 (0.80) 7.5 7.0 (1.74) 7.0 (1.74) NOTE -Shut unit off and remove manometer as soon as an accurate reading has been obtained. Takecare to replace pressure tap plug. NOTE -During this test procedure, the unit will be overt/ring: • Operate unit only long enough to obtain accurate reading to prevent overheating heat exchanger. • Attempts to clock gas valve during this procedure will be inaccurate. Measure gas flow rate only during normal 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 installations at altitudes from 0 to 7500 feet (0 to 2286 m). NOTE -In Canada, certification for installations at elevations over 4500 feet (1372 m) is thejurisdiction of local authorities. 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 anticipatorsetting (if adjustable) should be setaccordingto amps listedonwidngdiagramonunit. Flame Rollout Switch Factory set: No adjustment necessary. Limit Control Factoryset: No adjustmentnecessary. Pressure Switches Factoryset: Noadjustmentisnecessary. Fan Control The fan-ondelayof45 secondsisnotadjustable.The fan- off delay (time that the blower operates after the heating demand has been satisfied) can be adjustedby moving the jumper on the integrated control board. The unit is shipped witha factory fan-offdelay of180 seconds.The fan-off delay will affectcomfort and is adjustableto satisfy individual applications. See figure 36. Page 23 FAN*OFFDELAYADJUSTMENT 60sec, 90sec. 120sec, 180sec. To adjust fan-off delay, flip dip switch to desired setting. FIGURE 36 Temperature Rise Check temperature rise and, if necessary, adjust blower speed to maintain temperature rise withinrange shown on unit rating plate. Two-Stage Control The two-stagecontrolallowsthe field selection of one of three modes of operation: a-"TWO STAGE" operationcontrolledby a two-stage room thermostat; b-"ONE STAGE" operation controlled by a single- stage room thermostat(high heat only); and c-"W2 TIMED" operationwithsecondstagetimedON controlledby a single-stageroomthermostat.Three second-stage timed ON settings are available for field selection. They are 8, 12 and 15 minutes.(The factory setting is 8 minutes.) Refer to figure 31 for controlboard layout and jumper locations. Electrical 1 -Check all wiringfor loose connections. 2-Check circuitbreaker located on unit controlbox. 3 -Check for the correct voltage at the furnace (furnace operating). 4 -Check amp-draw on the blower motor. Motor Nameplate Actual NOTE -Do not secure electrical conduit directly to ducting or structure. Blower Speeds Refer to blower speed selection chart on unit wiring diagram. NOTE -CFM readings are takenextema/ to unitwitha dry evaporator coil fi/ter insta//ed and without any other accessories, Electronic Ignition The SureLight TM integratedcontrol has an added feature of an internal watchguard control The feature serves as an automatic reset devicefor ignitioncontrotslockedout because the burner has failed to light.After one hourof continuousthermostat demand for heat, the watchguard will break and remake thermostatdemand to the furnace and automaticallyreset the controlto relightthe furnace. Bumer Flame Start burnerand allow to operate for a few minutesto establishnormalburningconditions. Check burner flame by observation. Flame should be predominantly blue and strongin appearance. Check burnerflame periodicallytoensure properoperation. CAUTION Annual Service At the beginning of each heating season, systemshould be checked as follows by a qualified service technician: Electrical 1 -Check all wiringfor loos...

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