Lennox MERIT ML180UH045E36A Manual Download Page 6 | Manualshive

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Page 6

Control Box

(includes integrated control,

interlock switch and transformer)

Gas Valve

Burner Box

(includes sensor, ignitor

and rollout switches)

Combustion Air Inducer

Combustion Air Inducer

Pressure Switch

Heat Exchanger

Upper Access Panel

Blower Access Panel

Primary Limit

(under

combustion

air inducer)

Make-Up Box

Blower Assembly

Power Choke

(4 and 5 Ton Only)

PARTS ARRANGEMENT

FIGURE 1

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Summary of Contents for MERIT ML180UH045E36A

Page 1: ...Propane operation ML180UHE X model units are equipped with a hot sur face ignition system The ML180UHE X unit meets the California Nitrogen Oxides NOx Standards and Califor nia Seasonal Efficiency re...

Page 2: ...15 15 Shipping Data lbs 1 package 111 111 127 142 SPECIFICATIONS Gas Heating Performance Model No ML180UH090E60C ML180UH110E60C ML180UH135E60D Model No Low Nox ML180UH110XE60C 1 AFUE 80 80 80 Input B...

Page 3: ...h Altitude Pressure Switch Kit Natural Gas to LPG Propane Kit LPG Propane to Natural Gas Kit Natural Gas High Altitude Orifice Kit 0 4500 ft 4501 7500 ft 7501 10 000 ft 0 7500 ft 7501 10 000 ft 0 7500...

Page 4: ...35 0 70 1190 350 1000 235 855 205 790 190 540 140 0 80 1160 365 925 245 790 205 735 200 445 145 ML180UH070E36A PERFORMANCE Less Filter External Static Pressure in w g Air Volume Watts at Various Blowe...

Page 5: ...0 2255 640 1940 420 1750 310 1580 230 1485 185 2290 655 1980 425 1775 310 1605 235 1495 195 0 10 2200 655 1910 440 1705 315 1535 240 1385 190 2250 675 1945 445 1730 320 1555 245 1400 190 0 20 2150 675...

Page 6: ...er Box includes sensor ignitor and rollout switches Combustion Air Inducer Combustion Air Inducer Pressure Switch Heat Exchanger Upper Access Panel Blower Access Panel Primary Limit under combustion a...

Page 7: ...e hot surface ignition control system consisting of an in tegrated control figure 3 with control terminal designations in tables 1 2 and 3 sensor and ignitor figure 6 The in tegrated control and ignit...

Page 8: ...e Switch In 11 Rollout Switch In 12 Gas Valve Out TABLE 3 1 4 Quick Connect Terminals 120HUM Humidifier 120VAC LINE 120VAC XFMR Transformer 120VAC CIRC Indoor blower 120VAC EAC Indoor air quality acce...

Page 9: ...Switch failed to close or opened during heat demand 10 Watchguard Pressure Switch opened 5 times during one heat demand 11 Pressure Switch stuck closed prior to activation of combustion air inducer 12...

Page 10: ...out Switch Open 9 Pressure Switch failed to close or opened during heat demand 10 Watchguard Pressure Switch opened 5 times during one heat demand 11 Pressure Switch stuck closed prior to activation o...

Page 11: ...air temperature once the heat demand is satisfied Note the supply air temperature at the instant the blower is de energized Adjust the fan off delay to achieve a supply air tempera ture between 90 11...

Page 12: ...c er See figure 7 When excess heat is sensed in the heat exchanger the limit will open If the limit is open the in tegrated control energizes the supply air blower and clos es the gas valve The limit...

Page 13: ...ire 5 Connect lead to Terminal FS on integrated control 6 Turn supply voltage on and close thermostat contacts to cycle system 7 When main burners are in operation for two minutes take reading TABLE 6...

Page 14: ...s after the gas valve closes post purge A pressure switch mounted on the combustion air inducer orifice plate is used to prove inducer operation The com bustion air inducer orifice will be different f...

Page 15: ...diameter probes in order not to damage plug Check voltage during 20 second ignitor warm up period Voltage should read 120 volts 10 If voltage reads below these values check for correct supply voltage...

Page 16: ...ive to atmospheric pressure If the flue becomes obstructed during operation the switch senses a loss of negative pressure pressure becomes more equal with atmospheric pressure and opens the cir cuit t...

Page 17: ...then reinstall the mounting screws See unit Installation Instructions for more detail IMPORTANT The combustion air pressure switch must be moved for horizontal discharge air left position vent pipe v...

Page 18: ...roubleshooting Troubleshooting the motor is an easy process Follow steps below 1 Shut off power to unit 2 Remove input plugs P48 and P49 from motor See figure 14 for troubleshooting procedure If corre...

Page 19: ...peed tap used for continuous fan 1 2 3 4 or 5 on input plug P49 If 24 volts is not present problem may be up stream of plug P49 Proceed to test 4 Multi Meter set to VAC 12 0 12 0 24 Multi Meter set to...

Page 20: ...ximately the same resistance within an ohm 3 Check to see if the blower wheel spins freely Motor Test FIGURE 17 TABLE 9 Scale Measurement range in words ohms 2 M two megohm two million ohms 0 2 000 00...

Page 21: ...ervice is to be performed 3 Remove the upper access panel 4 Move gas valve switch to OFF position Do not force See figure 19 5 Replace the upper access panel B Safety or Emergency Shutdown Disconnect...

Page 22: ...fitting Connect to a test gauge to measure supply pressure 2 Start unit and allow 5 minutes for unit to reach steady state 3 After allowing unit to stabilize for 5 minutes record supply pressure and...

Page 23: ...0 135 Nat 3 5 3 5 2 9 3 5 4 5 13 0 LP Propane 10 0 10 0 9 6 10 0 11 0 13 0 TABLE 13 Pressure Switch and Gas Conversion Kits at all Altitudes Model Input Size High Altitude Pressure Switch Kit High Al...

Page 24: ...es a poor or partial ground Compare the readings to the table below If the readings exceed the maximum shown in table 14 make repairs before operating the furnace 2 In addition measure the AC voltage...

Page 25: ...ate TEMPERATURE RISE Supply Duct Temperature ________ Return Duct Temperature _ _____ Temperature Rise ________ SUPPLY AIR Temperatures RETURN AIR FIGURE 23 C External Static Pressure 1 Tap locations...

Page 26: ...t exchanger and clean if necessary 6 Check the cleanliness of blower assembly and clean the housing blower wheel and blower motor if necessary The blower motors are prelubricated for extended bearing...

Page 27: ...alve rollout switches primary limit switch and make up box then disconnect them 4 Remove the screws that secure the combustion air inducer pressure switch assembly to the collector box Carefully remov...

Page 28: ...NOx units only Replace NOx inserts 15 Reinstall collector box and combustion air assembly Reinstall all screws to the collector box and combustion air inducer Failure to replace all screws may cause l...

Page 29: ...rol energizes B6 combustion air inducer S18 combustion air pressure switch closes Once S18 closes a 15 second pre purge follows 6 A92 integrated control energizes R33 ignitor A 20 second warm up perio...

Page 30: ...OFF COMBUSTION AIR INDUCER ON INDOOR BLOWER ON HEATING SPEED LED FLASHES CODE 11 PRESSURE SWITCH CLOSED GAS VALVE OFF COMBUSTION AIR INDUCER OFF INDOOR BLOWER OFF WITH DELAY Sequence holds until press...

Page 31: ...NCE FOUR TIMES FLAME SIGNAL 1 5 MICROAMPS OR GREATER YES YES YES ROLLOUT SWITCH CLOSED LED FLASHES CODE 8 ROLLOT SWITCH OPEN GAS VALVE POWER OFF COMBUSTION AIR INDUCER POWER ON INDOOR BLOWER ON SEQUEN...

Page 32: ...SLOW FLASH RATE REMAINS UNCHANGED THROUGHOUT COOLING CYCLE THERMOSTAT CALLS FOR COOLING COMPRESSOR CONTACTOR AND SYSTEM FAN ENERGIZED WITH 2 SECOND DELAY COOLING SPEED EAC TERM ENERGIZED COMPRESSOR O...

Page 33: ...D EAC TERM REMAINS ON THERMOSTAT OPENS MANUAL FAN SELECTION MADE AT THERMOSTAT CONTROL G ENERGIZES SYSTEM FAN AT FAN SPEED EAC TERM ENERGIZED NO YES YES NO SYSTEM FAN SWITCHES TO HEAT SPEAD AFTER 30 S...

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