INSTALLATION INSTRUCTIONS ML180UHE 2011 Lennox Industries Inc. Dallas, Texas, USA MERIT® SERIES GAS FURNACE UPFLOW / HORIZONTAL AIR DISCHARGE 506810−01 06/2011 Supersedes 506732−01 Litho U.S.A. THIS MANUAL MUST BE LEFT WITH THE HOMEOWNER FOR FUTURE REFERENCE This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in manuals, be alert to the potential for personal injury or death.
Unit Dimensions − inches (mm) 1NOTE − 60C and 60D units that require air volumes over 1800 cfm (850 L/s) must have one of the following: 1. Single side return air with transition to accommodate 20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air filter. (Required to maintain proper air velocity.) 2. Single side return with optional return air base. 3. Bottom return air. 4. Return air from both sides. 5. Bottom and one side return air. See Blower Performance Tables for additional information.
Parts Arrangement Make−Up Box Heat Exchanger Combustion Air Inducer Combustion Air Inducer Pressure Switch Burner Box (includes sensor, ignitor and rollout switches) Gas Valve Primary Limit (under combustion air inducer) Control Box (includes integrated control, interlock switch and transformer) Upper Access Panel Secondary Limits Blower Assembly Blower Access Panel Power Choke (4 and 5 Ton Only) FIGURE 1 Page 3
ML180UHE Gas Furnace The ML180UHE unit is shipped ready for installation in the upflow or horizontal right position (for horizontal left position the combustion air pressure switch must be moved) fueled by natural gas. A conversion kit (ordered separately) is required for use in LP/Propane gas applications. The furnace is shipped with the bottom panel in place. The bottom panel must be removed if the unit is to be installed in a horizontal application. The panel may also be removed in upflow applications.
Installed in Combination with a Cooling Coil When this furnace is used with cooling units, it shall be installed in parallel with, or on the upstream side of, cooling units to avoid condensation in the heating compartment. See figure 2. With a parallel flow arrangement, a damper (or other means to control the flow of air) must adequately prevent chilled air from entering the furnace.
Do not install the furnace where drafts might blow directly into it. This could cause improper combustion and unsafe operation. Do not block the furnace combustion air openings with clothing, boxes, doors, etc. Air is needed for proper combustion and safe unit operation. When the furnace is installed in an attic or other insulated space, keep insulation away from the furnace.
Unconfined Space An unconfined space is an area such as a basement or large equipment room with a volume greater than 50 cubic feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the combined input rating of all appliances installed in that space. This space also includes adjacent rooms which are not separated by a door. Though an area may appear to be unconfined, it might be necessary to bring in outdoor air for combustion if the structure does not provide enough air by infiltration.
EQUIPMENT IN CONFINED SPACE ALL AIR FROM OUTSIDE (Inlet Air from Crawlspace and Outlet Air to Ventilated Attic) CHIMNEY OR GAS VENT VENTILATION LOUVERS (Each end of attic) OUTLET AIR FURNACE WATER HEATER INLET AIR VENTILATION LOUVERS (For unheated crawl space) NOTE−The inlet and outlet air openings shall each have a free area of at least one square inch (645 mm2) per 4,000 Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.
Upflow Applications Allow for clearances to combustible materials as indicated on the unit nameplate. Minimum clearances for closet or alcove installations are shown in figure 8. Setting Equipment WARNING Do not install the furnace on its front or its back. Do not connect the return air ducts to the back of the furnace. Doing so will adversely affect the operation of the safety control devices, which could result in personal injury or death.
Return Air −− Upflow Applications Single Side Return Air (with transition and filter) Return air can be brought in through the bottom or either side of the furnace installed in an upflow application. If the furnace is installed on a platform with bottom return, make an airtight seal between the bottom of the furnace and the platform to ensure that the furnace operates properly and safely. The furnace is equipped with a removable bottom panel to facilitate installation.
Removing the Bottom Panel Remove the two screws that secure the bottom cap to the furnace. Pivot the bottom cap down to release the bottom panel. Once the bottom panel has been removed, reinstall the bottom cap. See figure 11. Removing the Bottom Panel Horizontal Applications The ML180UHE furnace can be installed in horizontal applications. Order horizontal suspension kit (51W10) from Lennox, or use equivalent suspension method.
TABLE 1 Horizontal Application Unit Installed on Platform Furnace Cabinet Width Line contact is permissible but not preferred See the unit nameplate for clearances.
Venting A 4−inch diameter flue transition is factory-installed on the combustion air inducer outlet of all models. Figure 16 shows the combustion air inducer as shipped from the factory. Mounting Screws Location Flue Transition Mounting Screws 1 − Remove the four mounting screws (figure 15) which secure the combustion air inducer / pressure switch assembly to the orifice plate.
HORIZONTAL RIGHT POSITION HORIZONTAL LEFT POSITION Top Vent Discharge Top Vent Discharge Vent Pipe Vent Pipe Pressure Switch Pressure Switch Flue Transition Flue Transition AIR AIR FLOW FLOW Cover Plate Collector Box Make−Up Box Cover Plate Collector Box Make−Up Box Disconnect pressure switch hose from barbed fitting on the pressure switch assembly. Remove pressure switch assembly (1 screw) and cut wire tie to free pressure switch wires.
The ML180UHE series units are classified as fan−assisted Category I furnaces when vertically vented according to the latest edition of National Fuel Gas Code (NFPA 54 / ANSI Z223.1) in the USA. A fan−assisted Category I furnace is an appliance equipped with an integral mechanical means to either draw or force combustion products through the combustion chamber and/or heat exchanger. The ML180UHE is not approved for use with horizontal venting. NOTE − Use these instructions as a guide.
Common Venting Using Metal−Lined Masonry Chimney SEALED 5 ft. (1.5 m) minimum MAX. LENGTH −− SEE NOTE 1 BELOW. MIN. LENGTH −− AS SHORT AS PRACTICAL EXTERIOR CHIMNEY WITH METAL LINER VENT CONNECTOR 4 in. (102 mm) minimum FURNACE OTHER APPLIANCE PERMANENTLY SEALED FIREPLACE OPENING NOTE 1 − Refer to the provided venting tables for installations. Refer to the capacity requirements shown in the provided venting tables.
Common Venting Using Tile−Lined Interior Masonry Chimney and Combined Vent Connector MINIMUM LENGTH = AS SHORT AS PRACTICAL. FOR MAXIMUM LENGTH SEE NOTE TO LEFT INTERIOR TILE−LINED MASONRY CHIMNEY NOTE− Refer to provided venting tables for installations. NOTE − the chimney must be properly sized per provided venting tables or lined with listed metal lining system. VENT CONNECTOR OTHER APPLIANCE PERMANENTLY SEALED FIREPLACE OPENING FURNACE FIGURE 25 1-1/2 feet (.
two consecutive table size diameters over the size of the draft hood outlet or flue collar outlet. 20 − Do not install a manual damper, barometric draft regulator or flue restrictor between the furnace and the chimney.
TABLE 4 Capacity of Type B Double−Wall Vents with Single−Wall Metal Connectors Serving a Single Category I Appliance Vent and Connector Diameter − D (inches) Height H (feet) 6 8 10 15 20 30 Lateral L (feet) 3 Inch 4 Inch 5 Inch 6 Inch Appliance Input Rating in Thousands of Btu Per Hour MIN MAX MIN MAX MIN MAX MIN MAX 0 38 77 59 151 85 249 126 373 2 39 51 60 96 85 156 123 231 4 NA NA 74 92 102 152 146 225 6 NA NA 83 89 114 147 163 220 0 37 83 58 164
TABLE 5 Vent Connector Capacity Type B Double−Wall Vents with Type B Double−Wall Connectors Serving Two or More Category I Appliances Vent Height H (feet) 6 8 10 15 20 30 Vent and Connector Diameter − D (inches) Connector Rise R (feet) 3 Inch 4 Inch 5 Inch 6 Inch Appliance Input Rating in Thousands of Btu Per Hour MIN MAX MIN MAX MIN MAX MIN MAX 1 22 37 35 66 46 106 58 164 2 23 41 37 75 48 121 60 183 3 24 44 38 81 49 132 62 199 1 22 40 35 72 49 114 64
TABLE 7 Vent Connector Capacity Type B Double−Wall Vents with Single−Wall Metal Connectors Serving Two or More Category I Appliances Vent and Connector Diameter − D (inches) Height H (feet) 6 8 10 15 20 30 Lateral L (feet) 3 Inch 4 Inch 5 Inch 6 Inch Appliance Input Rating in Thousands of Btu Per Hour MIN MAX MIN MAX MIN MAX MIN 1 NA NA NA NA NA NA NA MAX NA 2 NA NA NA NA NA NA 168 182 3 NA NA NA NA 121 131 175 198 1 NA NA NA NA NA NA NA NA 2 NA NA N
Removal of the Furnace from Common Vent In the event that an existing furnace is removed from a venting system commonly run with separate gas appliances, the venting system is likely to be too large to properly vent the remaining attached appliances. Conduct the following test while each appliance is operating and the other appliances (which are not operating) remain connected to the common venting system.
Gas Piping Gas supply piping should not allow more than 0.5"W.C. drop in pressure between gas meter and unit. Supply gas pipe must not be smaller than unit gas connection. CAUTION If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall be installed at the gas valve and extend outside the furnace cabinet. The flexible connector can then be added between the black iron pipe and the gas supply line.
Left Side Piping (Standard) MANUAL MAIN SHUT−OFF VALVE (With 1/8 in. NPT Plugged Tap Shown) AUTOMATIC GAS VALVE AUTOMATIC GAS VALVE GROUND JOINT UNION MANUAL MAIN SHUT−OFF VALVE (With 1/8 in.
Leak Check After gas piping is completed, carefully check all piping connections (factory− and field−installed) for gas leaks. Use a leak detecting solution or other preferred means. NOTE − If emergency shutoff is necessary, shut off the main manual gas valve and disconnect the main power to the furnace. The installer should properly label these devices. The unit is equipped with a field make−up box on the left hand side of the cabinet.
Before connecting the thermostat, check to make sure the wires will be long enough for servicing at a later date. Make sure that thermostat wire is long enough to facilitate future removal of blower for service. Complete the wiring connections to the equipment. Use the provided unit wiring diagram and the field wiring diagram shown in figure 33. Use 18−gauge wire or larger that is suitable for Class II rating for thermostat connections.
ML180UHE Schematic Wiring Diagram and Sequence of Operation 3 10 1 5 2 5 9 7 4 8 6 1 1− Line voltage is applied to L1 and N. the T1 low voltage transformer is energized, and line voltage is applied to B3 indoor blower. 2− S47 rollout switch(es) must be closed in order for 24V from transformer to be output on integrated control "R" to power thermostat. 3− When there is a call for heat, W1 of the thermostat energizes W of the furnace control with 24VAC.
TYPICAL ML180UHE FIELD WIRING DIAGRAM FIGURE 33 TABLE 10 INTEGRATED CONTROL (Automatic Hot Surface Ignition System) 1/4" QUICK CONNECT TERMINALS 120HUM Humidifier 120VAC LINE 120VAC XFMR Transformer 120VAC CIRC Indoor blower 120VAC EAC Indoor air quality accessory 120VAC NEUTRALS Common 120VAC HUM24 Humidifier 24VAC 3/16" QUICK CONNECT TERMINALS RED LED COOL Cooling tap 24VAC HEAT Heating tap 24VAC FAN Continuous blower 24 VAC PARK (no power) Park terminal for speed taps FLAME/FS F
Unit Start−Up FOR YOUR SAFETY READ BEFORE LIGHTING WARNING Do not use this furnace if any part has been underwater. A flood−damaged furnace is extremely dangerous. Attempts to use the furnace can result in fire or explosion. Immediately call a qualified service technician to inspect the furnace and to replace all gas controls, control system parts, and electrical parts that have been wet or to replace the furnace, if deemed necessary.
11 − Are flame rollout switches tripped? If flame rollout switches are tripped, call the service technician for inspection. Heating Sequence Of Operation (follow steps below or see Figure 32 for more detail) 1 − When thermostat calls for heat, combustion air blower starts. 2 − Combustion air pressure switch proves blower operation. Switch is factory−set and requires no adjustment. 3 − After a 15−second prepurge, the hot surface ignitor energizes.
TABLE 13 Manifold Pressure Settings at all Altitudes Model Input Size 045 070 090 110 135 Line Pressure in.wg. Gas 0−2000 ft 2001−4500 ft. 4501−7500 ft 7501 − 10,000 ft Min Max Nat 3.5 3.2 3.0 3.5 4.5 13.0 LP/propane 10.0 10.0 10.0 10.0 11.0 13.0 Nat 3.5 3.2 2.8 3.5 4.5 13.0 LP/propane 10.0 10.0 10.0 10.0 11.0 13.0 Nat 3.5 3.2 2.7 3.5 4.5 13.0 LP/propane 10.0 10 9.6 10.0 11.0 13.0 Nat 3.5 3.5 3.0 3.5 4.5 13.0 LP/propane 10.0 10.0 9.6 10.0 11.
Input Voltage Requirements The circuit is designed to be operated with AC voltage. A voltage of 12 to 33VAC is required to energize the motor. Expected current draw will be less than 20mA. Blower Speeds Follow the steps below to change the blower speeds. HEAT FAN-OFF TIME IN SECONDS NO JUMPER 1 − Turn off electrical power to furnace. To adjust fan−off timing, reposition jumper across pins to achieve desired setting.
BLOWER DATA ML180UH045E36A PERFORMANCE (Less Filter) External Static Pressure in. w.g. Air Volume / Watts at Various Blower Speeds cfm Watts cfm Watts cfm Watts cfm Watts cfm Watts 0.00 1380 265 1155 165 995 120 975 115 945 105 High Medium-High Medium Medium-Low Low 0.10 1345 270 1120 175 950 120 880 105 865 100 0.20 1320 285 1080 190 900 125 805 105 700 85 0.30 1290 295 1055 200 875 135 750 110 640 90 0.
BLOWER DATA ML180UH090E60C PERFORMANCE (Less Filter) Air Volume / Watts at Different Blower Speeds External Bottom Return Air, Side Return Air with Optional Return Single Side Return Air − Air volumes in bold require field Static Air Base, Return Air from Both Sides or Return Air from fabricated transition to accommodate 20 x 25 x 1 in. air filter in order to maintain proper air velocity. Pressure Bottom and One Side. in. w.g.
Service WARNING ELECTRICAL SHOCK, FIRE, OR EXPLOSION HAZARD. Failure to follow safety warnings exactly could result in dangerous operation, serious injury, death or property damage. Improper servicing could result in dangerous operation, serious injury, death, or property damage. Before servicing, disconnect all electrical power to furnace. When servicing controls, label all wires prior to disconnecting. Take care to reconnect wires correctly. Verify proper operation after servicing.
ML180UHE BURNER, COMBUSTION AIR INDUCER ASSEMBLY & HEAT EXCHANGER REMOVAL Gasket Flue Transition Pressure Switch Rollout Switches (−090, −110 −135 units) Rollout Switches (−045 and −070 units) Heat Exchanger Ignitor Orifice Plate Collector Box Combustion Air Inducer Sensor Retention Rings Cross Over Manifold And Gas Valve FIGURE 37 Remove 5 screws if necessary (either side of cabinet) ML180UHE NOx INSERTS 1 2 3 4 5 NOx Insert FIGURE 38 CAUTION Some soaps used for leak detection are corrosive to cer
Planned Service The following items should be checked during an annual inspection. Power to the unit must be shut off for the service technician’s safety. Fresh air grilles and louvers (on the unit and in the room where the furnace is installed) − Must be open and unobstructed to provide combustion air. Operating performance − Unit must be observed during operation to monitor proper performance of the unit and the vent system. Burners − Must be inspected for rust, dirt, or signs of water.
Integrated Control Diagnostic Codes RED LED Flash Code Diagnostic Codes / Status of Furnace Off No power to control or board fault detected On Board fault detected, Heartbeat1 Control powered − displayed during all modes of operation if no errors are detected 1 Reverse Line Voltage Polarity 2 Improper Earth Ground 3 Burner failed to light, or lost flame during heat demand 4 Low Flame Signal − check flame sensor 5 Watchguard − burner failed to light, exceeded maximum number of retries or rec
Troubleshooting: Heating Sequence of Operation HEATING SEQUENCE OF OPERATION ABNORMAL HEATING MODE NORMAL HEATING MODE POWER ON GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER DELAY OFF. LED SLOW FLASH (RESET CONTROL BY TURNING MAIN POWER OFF.) NO CONTROL SELF−CHECK OKAY? YES NO LED FLASHES CODE 1 − POLARITY REVERSED. IS POLARITY CORRECT? YES NO LED FLASHES CODE 2 − IMPROPER GROUND. IS THERE A PROPER GROUND? YES NO LED FLASHES CODE 13 − LOW LINE VOLTAGE.
Troubleshooting: Heating Sequence of Operation (Continued) HEATING SEQUENCE CONTINUED NORMAL HEATING MODE ABNORMAL HEATING MODE 15-SECOND COMBUSTION AIR INDUCER PREPURGE INITIATED BY CLOSED PRESSURE SWITCH. YES NO NO IS VOLTAGE ABOVE 70 VOLTS? IGNITOR WARM-UP −− 20 SECONDS. YES 4-SECOND TRIAL FOR IGNITION. GAS VALVE OPENS. IGNITOR ENERGIZED FOR FIRST 3 SECONDS OF THE TRIAL. YES FLAME STABILIZATION PERIOD. YES LED FLASHES CODE 13 − LOW LINE VOLTAGE.
Troubleshooting: Cooling Sequence of Operation COOLING SEQUENCE OF OPERATION NORMAL COOLING MODE ABNORMAL COOLING MODE POWER ON IGNITION CONTROL MAIN POWER ON. NO CONTROL SELF DIAGNOSTIC CHECK. IS CONTROL OPERATING NORMALLY? GAS VALVE OFF. COMBUSTION AIR INDUCER OFF. INDOOR BLOWER OFF WITH NORMAL DELAY. SIGNAL CIRCUIT BOARD FAILURE AT LED. INTERRUPT MAIN POWER TO RESET CONTROL.
Troubleshooting: Continuous Fan Sequence of Operation CONTINUOUS FAN SEQUENCE OF OPERATION LED: SLOW FLASH RATE REMAINS UNCHANGED THROUGHOUT SEQUENCE. MANUAL FAN SELECTION MADE AT THERMOSTAT. CONTROL (G) ENERGIZES SYSTEM FAN AT FAN SPEED. EAC TERMINAL IS ENERGIZED. THERMOSTAT CALLS FOR HEAT (W). YES NO THERMOSTAT CALLS FOR COOLING. YES SYSTEM FAN SWITCHED TO COOL SPEED. EAC TERM. REMAINS ON. NO SYSTEM FAN CONTINUES FAN SPEED WITHOUT INTERRUPTION. EAC TERMINAL REMAIN ON.
Start−Up & Performance Check List UNIT SET UP (typical) Unit Model Number_______________ Serial Number___________________ 2 SUPPLY AIR Line Voltage 5 2 upflow furnace shown 1 3 Gas Supply Pressure Filter 1 RETURN AIR 4 1 3 GAS SUPPLY Natural Gas DUCT SYSTEM SUPPLY AIR DUCT LP/Propane Gas Sealed Piping Connections Tight Leak Tested Insulated (if necessary) Supply Line Pressure W.C.
UNIT OPERATION (typical) Combustion CO2 2 SUPPLY AIR Gas Manifold Pressure 7 Thermostat Temperatures 6 upflow furnace shown 1 4 Filter Blower Motor Amps Duct Static 3 RETURN AIR COOLING MODE HEATING MODE 1 GAS MANIFOLD PRESSURE W.C.
