Lenox Lennox Merit Series Gas Furnace Upflow/Horizontal air discharge Venting, Upflow Position

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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

 

FIGURE 15

UPFLOW POSITION

Top Vent Discharge

Flue

Vent Pipe

 

Transition

Collector Box

Pressure

 

Switch

 

Make−Up

 

Box

 

AIR

FLOW

FIGURE 16

IMPORTANT

The unit will not vent properly with the flue transition pointed down in the 6 o’clock position.

The combustion air inducer may be rotated clock- wise or counterclockwise by 90° to allow for top or side vent discharge in all applications. When the unit is installed, the flue transition must be in the 9 o’clock, 12 o’clock or 3 o’clock position.

If necessary, reposition the combustion air inducer, pres- sure switch and/or make−up box as needed per the follow- ing steps. See figures 17 through 21.

1 − Remove the four mounting screws (figure 15) which secure the combustion air inducer / pressure switch assembly to the orifice plate. Lift the assembly and ro- tate it 90 degrees clockwise or counterclockwise to ei- ther the 3 o’clock position or to 9 o’clock position. Re− secure with four screws. Gasket should be left in place.

2 − Use tin snips to cut preferred opening on the cabinet for repositioning the flue outlet. Use the cut−out piece as a cover plate to patch unused opening on cabinet.

UPFLOW POSITION

Left Side Vent Discharge

Cover Plate

Collector Box

Pressure

 

Switch

Make−Up

 

Box

Vent Pipe

 

Flue

Transition

AIR FLOW

DGas supply piping must be brought into the unit from the right side in order to accommodate the flue pipe.

DCut Combustion air inducer tubing from 9" to 8" to avoid inter- ference with inducer motor

DRemove make−up box assembly (2 screws) and cut wire tie to free make−up box wires. Re−install make−up box on other side of cabinet.

DRe−secure make−up box wires: Either pull excess wires through the blower compartment and secure using supplied wire tie, or coil excess wire and secure to the gas manifold.

FIGURE 17

UPFLOW POSITION

Right Side Vent Discharge

Collector Box

Cover Plate

Flue Transition

 

Vent Pipe

 

 

Pressure

 

 

Switch

 

 

Make−Up

Box

AIR FLOW

DCut combustion air inducer tubing from 9" to 5" to avoid interference with inducer motor

FIGURE 18

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Contents Table of Contents Installation Instructions ML180UHETOP View Unit Dimensions − inches mmMake−Up Box Heat Exchanger Combustion Air Inducer Parts ArrangementBurner Box Gas ValveML180UHE Gas Furnace Safety InformationShipping and Packing List General Use of Furnace as Construction HeaterCombustion, Dilution & Ventilation Air Equipment in Confined Space ALL AIR from Inside Equipment in Confined Space Setting Equipment Return Air Right Horizontal Application Installation Clearances Top LeftEnd Bottom Typical Horizontal ApplicationDuct System FiltersUpflow Position VentingTop Vent Discharge Left Side Vent DischargeHorizontal Left Position Horizontal Left Position Horizontal Right PositionSide Vent Discharge Side Vent Discharge − no modifications necessaryVent Connection Upflow and Horizontal Position Common Venting Using Metal−Lined Masonry Chimney −1/2 18 − The common vent diameter must always be at least as Cated or common venting system, you must inspectFeet FAN + FAN FAN + NAT 130 Carbon Monoxide Poisoning Hazard − In some localities, codes may require the installation Ers or straps. Install a drip leg in vertical pipe runs toGas Piping Gas supply piping should not allow more than 0.5W.C. dropLeft−Side Air Discharge Horizontal ApplicationRight−Side Air Discharge Electrical Interior MAKE−UP BOX InstallationElectrostatic Discharge ESD Thermostat Designations ML180UHE Schematic Wiring Diagram and Sequence of Operation Integrated Control Typical ML180UHE Field Wiring DiagramUnit Start−Up For Your Safety Read Before LightingGAS Meter Clocking Chart Gas Pressure AdjustmentProper Combustion High AltitudeManifold Pressure Settings at all Altitudes Other Unit AdjustmentsNo Jumper Heat FAN-OFF Time in Seconds995 1380975 115 945 1345Order to maintain proper air velocity Single Side Return Air − Air volumes in bold require field640 1940 420 1750 310 230Electrical SHOCK, Fire Or Explosion Hazard ServiceHeat Exchanger Removal ML180UHE BURNER, Combustion AIR Inducer Assembly−090, −110 −135 units −045 and −070 unitsRepair Parts List Planned ServiceRED LED Integrated Control Diagnostic CodesHeating Sequence of Operation Normal Heating Mode Abnormal Heating ModeHeating Sequence Cooling Sequence of Operation Normal Cooling Mode Abnormal Cooling ModeContinuous FAN Sequence of Operation Start−Up & Performance Check List Temperature Rise Cooling ModeUnit Operation Drain Line