Lennox International Inc Merit Series Gas Furnace Unit Dimensions − inches mm, TOP View

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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.

2Flue outlet may be horizontal but furnace must be vented vertically

3Optional external side return air filter kit cannot be used with the optional RAB Return Air Base.

3−1/8 (79)

D

SUPPLY AIR

OPENING

FLUE OUTLET

(Top)

3 OPTIONAL

 

 

 

 

23−3/4

 

 

 

 

 

 

EXTERNAL

 

 

 

 

 

(603)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SIDE RETURN

 

25

 

 

 

AIR FILTER KIT

 

 

 

(635)

 

 

 

 

 

 

 

(Either Side)

 

 

 

TOP VIEW

 

A

 

 

 

B

9/16 (14)

 

 

3OPTIONAL

 

 

EXTERNAL

 

 

SIDE RETURN

 

 

AIR FILTER KIT

 

 

(Either Side)

 

 

 

33

 

 

 

(838)

 

 

14−3/4

 

 

(375)

 

 

 

16

 

 

 

(406)

 

 

 

5/8

3/4

C

3/4

(16)

(19)

(19)

 

1Bottom Return

 

 

Air Opening

 

 

FRONT VIEW

3/4(19)

27−3/4

 

Front Panel

(705)

 

 

 

3−1/4 (83)

 

 

3 (76) Right

19−7/16

9/16

(14)

6−3/4 (171) Left

(494)

 

 

2 FLUE OUTLET

 

 

9−1/8 (232) Right

(Either Side)

 

 

ELECTRICAL INLET

 

8−5/8 (219) Left

 

(Either Side)

 

 

 

 

 

5−3/8 (137) Right

GAS PIPING INLET

 

1−9/16 (40) Left

(Either Side)

 

 

ELECTRICAL

23

 

1−1/2

INLET (Either Side)

 

(584)

 

(38)

 

1 Side Return

14

 

(Either Side)

Air Opening

(356)

 

 

(Either Side)

 

 

 

1−15/16 (49)

 

3−1/4

23−1/2

 

 

(83)

(597)

 

 

 

1Bottom Return

 

 

 

Air Opening

 

 

SIDE VIEW

ML180UH Model No.

 

A

 

B

 

C

 

D

in.

 

mm

in.

 

mm

in.

 

mm

in.

 

mm

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

045P24A

 

 

 

 

 

 

 

 

 

 

 

 

045P36A

14−1/2

 

368

13−3/8

 

340

13

 

330

4−3/4

 

121

070P24A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

070P36A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

090P36B

17−1/2

 

446

16−3/8

 

416

16

 

406

6−1/4

 

159

090P48B

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

110P48C

21

 

533

19−7/8

 

504

19−1/2

 

495

8

 

203

110P60C

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

135P60D

24−1/2

 

622

23−3/8

 

546

23

 

584

9−3/4

 

248

 

 

 

 

 

 

 

 

 

 

 

 

 

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Contents Installation Instructions ML180UH Table of ContentsUnit Dimensions − inches mm TOP ViewParts Arrangement Shipping and Packing List Safety InformationML180UH Gas Furnace Use of Furnace as Construction Heater GeneralCombustion, Dilution & Ventilation Air Equipment in Confined Space ALL AIR from Inside Equipment in Confined Space Setting Equipment Return Air Plenum End Bottom Horizontal Application Installation Clearances Top LeftRight Filters Duct SystemTop Vent Discharge VentingUpflow Position Left Side Vent DischargeSide Vent Discharge Horizontal Left PositionHorizontal Right Position Vent Connection Upflow and Horizontal Position Common Venting Using Metal−Lined Masonry Chimney −1/2 Cated or common venting system, you must inspect 18 − The common vent diameter must always be at least asFeet FAN + FAN FAN + NAT 112 175 169 278 Carbon Monoxide Poisoning Hazard Gas Piping Ers or straps. Install a drip leg in vertical pipe runs to− In some localities, codes may require the installation Every 8 to 10 feet 2.44 to 3.01 m with suitable hangRight−Side Air Discharge Horizontal ApplicationLeft−Side Air Discharge Electrostatic Discharge ESD Interior MAKE−UP BOX InstallationElectrical Thermostat Designations ML180UH Schematic Wiring Diagram and Sequence of Operation Typical ML180UH Field Wiring Diagram Integrated ControlFor Your Safety Read Before Lighting Unit Start−UpHigh Altitude Gas Pressure AdjustmentProper Combustion Other Unit Adjustments Manifold Pressure Settings at all AltitudesHeat FAN-OFF Time in Seconds No Jumper680 453 900750 885860 Single Side Return Air − Air volumes in bold require field1391 653Service Electrical SHOCK, Fire Or Explosion Hazard−090, −110 −135 units ML180UH BURNER, Combustion AIR Inducer AssemblyHeat Exchanger Removal −045 and −070 unitsPage Planned Service Repair Parts ListIntegrated Control Diagnostic Codes DescriptionTroubleshooting Heating Sequence of Operation Normal Heating Mode Abnormal Heating ModeHeating Sequence Troubleshooting Cooling Sequence of Operation Normal Cooling Mode Abnormal Cooling ModeTroubleshooting Continuous Fan Sequence of Operation Continuous Heat Speed FAN Sequence of Operation

Merit Series Gas Furnace specifications

Lennox International Inc. is a leading name in the heating and cooling industry, and their Merit Series Gas Furnace embodies the commitment to quality and efficiency that the company is known for. The Merit Series is designed to provide reliable heating in a sustainable manner, making it an excellent choice for homeowners seeking comfort without excessive energy bills.

One of the standout features of the Merit Series Gas Furnace is its efficiency ratings. The units in this series typically boast Annual Fuel Utilization Efficiency (AFUE) ratings of up to 95%. This level of efficiency means that the furnace converts a significant portion of the fuel it uses into heat, ultimately lowering operating costs. Such energy-efficient performance is not only beneficial for the wallet but also promotes environmental sustainability.

The Merit Series also incorporates advanced technologies that enhance its operation. The inclusion of a multi-speed blower motor is a notable feature that provides thoughtful airflow management throughout the home. By adjusting the speed according to the heating needs, the furnace optimizes comfort levels while minimizing noise and energy consumption. Homeowners can enjoy a warm environment without the disruptive sounds often associated with traditional furnaces.

Moreover, the Merit Series comes equipped with durable construction materials designed to withstand the test of time. From the robust heat exchanger to the heavy-gauge cabinet, Lennox focuses on longevity and reliability. This ensures that homeowners can trust their furnace to operate effectively even in the harshest winter conditions.

Safety features are also integral to the design of the Merit Series Gas Furnace. With an integrated Flame Sensor and a built-in safety shut-off system, the furnace ensures that any irregularities in operation are promptly detected and addressed. Such measures provide peace of mind for families using the heating system throughout the cold months.

Installation and maintenance are further simplified with the Merit Series. Its design facilitates easier access for HVAC professionals, allowing for quicker installations and routine service, ensuring that homeowners spend less time and money on upkeep.

In conclusion, Lennox International Inc.'s Merit Series Gas Furnace combines efficiency, advanced technology, and robust construction, making it a top choice for families looking to enhance their home's heating system. With its energy-saving innovations and commitment to reliability, the Merit Series stands as an exemplary option in today’s market.
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