Lennox ML180UHE(K) Merit Series Gas Furnace

Model Number Identification

The model number provides key information about the furnace configuration:

• Unit Type: ML = Merit® Series
• Stages: 1 = Single-Stage
• AFUE: 80 = 80%
• Configuration: UH = Upflow/Horizontal
• Nominal Gas Heat Input: Options range from 045 (44,000 Btuh) to 135 (132,000 Btuh).
• Blower: E = High Efficiency Constant Torque Blower Motor
• Low NOx: X = Units meet California Nitrogen Oxides Standard (40 ng/J).
• Refrigerant Detection: K = Refrigerant Detection-Ready
• Cabinet Width: Options include A (14-1/2 in.), B (17-1/2 in.), C (21 in.), D (24-1/2 in.).
• Nominal Add-On Cooling Capacity: Options include 36 (1.5-3 tons), 48 (2.5-4 tons), 60 (3-5 tons).

Note: Indoor coils with the same letter designation physically match the furnace.

Feature Highlights

The ML180UHE(K) furnace incorporates several advanced features:

1. Lennox Duralok™ Heat Exchanger Assembly: Heavy gauge aluminized steel with a crimped seam clamshell design for durability and efficient heat transfer.
2. Inshot Burners: Aluminized steel burners ensure efficient, trouble-free operation with proper air-gas mixture for combustion.
3. SureLight® Hot Surface Ignitor: A reliable silicon nitride ignitor provides long-lasting, trouble-free performance.
4. Gas Control Valve: A 24-volt redundant combination gas control valve integrates manual shut-off, automatic electric valve, and gas pressure regulation.
5. Combustion Air Inducer: A shaded pole blower efficiently purges the heat exchanger and vents flue products. A pressure switch ensures proper operation before gas valve opening.
6. Flame Rollout Switches (2): Factory-installed switches provide protection against abnormal operating conditions, featuring manual reset.
7. Limit Control: Accurately located primary limit with automatic reset.
8. Power Saver™ Constant Torque Blower Motor: A programmable, high-efficiency ECM motor provides consistent airflow across various static pressures.
9. SureLight® Integrated Furnace Control: Manages all furnace operations, including pre- and post-purge cycles, flame sensing, and lockout procedures. Features a diagnostic LED display.
10. Insulated Cabinet: Foil-faced insulation on sides and back of the heating compartment reduces heat loss and noise.
11. Safety Interlock Switch: Automatically shuts off power when the blower compartment access panel is removed.
12. Gas Piping and Electrical Inlets: Conveniently located on both sides of the cabinet.

Applications and Warranty

Approvals

• AHRI Certified
• Tested and rated according to US DOE test procedures and FTC labeling regulations
• ISO 9001 Registered Manufacturing Quality System
• Blower data from unit tests conducted in Lennox Laboratory air test chamber
• All models meet UL 60335-2-40 Refrigerant Detector Requirements

Note: This furnace is not CSA International design certified for installation in mobile homes, recreational vehicles, or outdoors.

California Specifics

These furnaces do not meet the South Coast Air Quality Management District (SCAQMD) Rule 1111 and San Joaquin Valley Air Pollution Control District (SJVAPCD) Rule 4905 NOx emission limit (14 ng/J) and cannot be installed within these districts.

All “X” model furnaces are approved by the California Energy Commission and meet California Nitrogen Oxides Standard (NOx) limits of 40 ng/J.

Warranty

• Heat Exchanger: Limited twenty years (residential), limited ten years (non-residential).
• All other covered components: Limited five years (residential), limited one year (non-residential).

Note: Refer to Lennox® Basic Limited Warranty at www.Lennox.com for additional details.

Features in Detail

Heating System

• Lennox Duralok™ Heat Exchanger Assembly: Features heavy gauge aluminized steel, crimped seam clamshell design for normal expansion and contraction, and minimum resistance to airflow. Laboratory life cycle tested.
• Inshot Burners: Aluminized steel burners provide efficient, trouble-free operation. Burner venturi mixes air and gas for proper combustion. Removable as a single component for service.
• SureLight® Hot Surface Ignitor: Tough, reliable, long-life performance with a silicon nitride ignitor cemented to a steatite block. Ignition leads use nickel-plated copper with high-temperature Teflon® insulation.
• Gas Control Valve: 24 volt redundant combination gas control valve combines manual shut off, automatic electric valve, and gas pressure regulation.
• Combustion Air Inducer: Shaded pole heavy duty blower prepurges heat exchanger and safely vents flue products. Pressure switch proves blower operation. Operates only during heating cycle. Direct access allows 90° rotation for easy vent attachment.
• Flame Rollout Switches (2): Factory installed on the front of the burner box, providing protection from abnormal operating conditions. Manual reset.
• Limit Control: Primary limit accurately located on vestibule panel with automatic reset.

Blower and Controls

Blower

• Power Saver™ Constant Torque Blower Motor: Programmable high efficiency multi-speed motor. Achieved via ECM motor. Leadless blower motor with simple plug-in connections. Controlled by the Integrated Furnace Control. Blower speeds are easily changed on the integrated furnace control.
• Blower Assembly: Lennox designed and built, direct drive blower, statically and dynamically balanced. Resiliently mounted motor. Easily removed for servicing.

Controls

• SureLight® Integrated Furnace Control: Contains all necessary controls and relays. Operates combustion air inducer with a 15-second pre-purge cycle. Post-purge cycle for 5 seconds. Flame sensor ensures safe operation. If flame is lost, control attempts ignition 4 times before lockout for 60 minutes. Watchguard circuit resets ignition controls after one hour of continuous thermostat demand. Features a seven-segment LED display for diagnostics and system status. Diagnostic codes stored in non-volatile memory. Port on blower door for easy viewing. Fan control includes adjustable blower timed-off delay (60, 90, 120, 180 seconds) and fixed blower timed-on delay (30 seconds heating, 2 seconds cooling). For air-conditioning, blower automatically energizes on thermostat demand for cooling. Two accessory terminals for 24V accessories (less than 0.5 amp).

Optional Accessories

• High Altitude Pressure Switch Kit: Required for proper operation at altitudes from 4,501 to 7500 ft.
• Natural Gas to LPG/Propane Conversion Kit: Required for field changeover.
• LPG/Propane to Natural Gas Conversion Kit: Required for field changeover.
• Vent Adaptor (Upflow Applications Only): Allows venting through a masonry chimney without a flue liner. Manual reset temperature sensor protects against abnormal conditions. Sensor wiring can be routed from either side. Minimum winter design temperatures: -10°F (interior masonry), +5°F (exterior masonry).
• M30 Smart Wi-Fi Thermostat: Wi-Fi-enabled, electronic 7-day, universal, multi-stage, programmable touchscreen thermostat with 4 Heat/2 Cool, auto-changeover, and dual-fuel control. Offers enhanced capabilities including humidification/dehumidification, Humiditrol® control, and maintenance reminders. Features a 4.3-inch color touchscreen, LCD display, Smooth Setback Recovery, compressor short-cycle protection, up to four schedules, One-Touch Away Mode, Smart Away™ geo-fencing, and Wi-Fi remote monitoring. Compatible with Amazon Alexa® and Google Assistant.
• Remote Outdoor Temperature Sensor: Used with the M30 Smart Wi-Fi Thermostat to display outdoor temperature. Required for Enhanced Dehumidification Accessory (EDA).
• Thermostat: Not furnished with unit.
• Blower Relay Kit (For Use With Two-Stage Outdoor Units): Allows furnace blower speed changes when matched with two-stage air conditioners or heat pumps.
• Transformer (75VA): Recommended for zoning or dual-fuel systems and other 24V accessories requiring higher VA rating. Replaces the standard 40VA transformer.

Cabinet Features

• Cabinet: Low-profile, narrow width for easy installation. Heavy-gauge, cold rolled steel construction with pre-painted finish. Flue outlet on top for upflow, relocatable to sides for horizontal. Supply air opening flanges for easy plenum connection.
• Insulated Cabinet: Foil-faced insulation on sides and back of heating compartment.
• Sealed Blower Compartment: Inner blower compartment access panel seals blower compartment from air leakage.
• Complete Service Access: Allows for easy maintenance.
• Safety Interlock Switch: Automatically shuts off power to the unit when the blower compartment access panel is removed.
• Gas Piping and Electrical Inlets: Provided on both sides of the cabinet.
• Low Leakage Cabinet: Meets ANSI/ASHRAE Standard 193-2010 for air tightness (less than 2% air leakage).

Bottom/Side Return Air Entry

• Upflow/horizontal with bottom return air entry: Remove furnished bottom seal panel.
• Upflow only with side return-air entry: Corners marked for return air cut-out.

Note: 60C and 60D size units requiring over 1800 cfm must use one of the following for proper velocity: Single side return air with Optional Return Air Base and transition, bottom return air, return air from both sides, or bottom and one side return air. Refer to Blower Performance Tables.

Coil Match-Up

Furnaces exactly match Lennox cased upflow indoor coils and horizontal indoor coils with the same letter designation (A, B, C, D) in the model number. No adaptor required. Engaging holes on the cabinet ensure alignment. Lennox uncased coils match furnaces without overhang but require an optional adaptor base or field fabricated transition.

Indoor Air Quality Products

• Healthy Climate® PureAir® Air Purification System: Filtration with Carbon Clean 16® media filter (MERV 16) captures over 95% of particles 0.3 microns and larger. Highest airflow performance and lowest pressure drop. Long life filters up to 1 year.
• Healthy Climate® Media Air Cleaner: High performance in a narrow 7 in. cabinet. Available with MERV 11, 13, or 16 rated filters. Multi-position heavy gauge steel cabinet. Tool-less entry and assembly.
• Healthy Climate® Whole Home In Duct Air Purifiers: Compact duct-mounted design, effective against odors and VOCs, certified ozone-free, UVC lamp and carbon cells. Safety interlocks. Low power consumption.
• Healthy Climate® Ultraviolet Germicidal Lights: Compact duct-mounted design, single or dual applications, certified ozone-free. Effective against odors. Safety interlocks.

Specifications Tables

Detailed specifications for various models are provided in the following tables, covering Gas Heating Performance, Blower Data, and Shipping Data.

Gas Heating Performance

Specifications for Additional Models

Installation Clearances

Clearances vary based on installation position (Upflow or Horizontal) and vent type (B1 or C).

Upflow Position

Notes: Air for combustion must conform to NFPA 54/ANSI-Z223.1. U.S. flue sizing must conform to current National Fuel Gas Code or applicable local building codes.

Horizontal Position

Notes: Air for combustion must conform to NFPA 54/ANSI-Z223.1. U.S. flue sizing must conform to current National Fuel Gas Code or applicable local building codes. Line contact installation permissible between jacket top or sides and building joists.

Optional Accessories - Order Separately

Cabinet Accessories

Controls

Filters

Venting

1 Cleanable polyurethane, frame-type filter.

Gas Heat Accessories

High Altitude Pressure Switch Kit

High Altitude Derate

Units may be installed at altitudes up to 2000 ft. without modifications. At altitudes above 2000 ft., units must be derated according to the table below. This is the only permissible derate.

1 Natural Gas High Altitude Orifice Kit required.

Dimensions - Unit - Upflow Position

Diagrams and tables illustrate unit dimensions for upflow installation.

Note: 60C and 60D size units requiring air volumes over 1800 cfm must have one of the following: Single side return air with Optional Return Air Base and transition, bottom return air, return air from both sides, or bottom and one side return air. Refer to Blower Performance Tables for additional information.

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

Optional External Side Return Air Filter Kit is not for use with the Optional Return Air Base.

Dimensions - Unit - Horizontal Position

Diagrams illustrate unit dimensions for horizontal installations, with options for left-hand and right-hand air discharge.

Dimensions - Optional Accessories

Horizontal (End) Filter Kit

Optional Return Air Base

(Upflow Applications Only - For use with A, B, C and D cabinets)

Note: Optional Side Return Air Filter Kits are not for use with Optional Return Air Base.

Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.

Minimum unit side return air opening dimensions for units requiring 1800 cfm or more of air (W x H): 23 x 11 in. (584 x 279 mm).

The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown.

Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return air opening. The size of the opening must not extend beyond the markings on the furnace cabinet.

To minimize pressure drop, the largest opening height possible, up to 14 in. (356 mm), is preferred.

Blower Data

Detailed blower performance data, including air volume and watts at various blower speeds and static pressures, is provided for different models.

ML180UH045E36AK PERFORMANCE (Less Filter)

ML180UH070E36AK PERFORMANCE (Less Filter)

ML180UH070E36BK PERFORMANCE (Less Filter)

ML180UH090E48BK PERFORMANCE (Less Filter)

ML180UH090E60CK PERFORMANCE (Less Filter)

ML180UH135E60DK PERFORMANCE (Less Filter)

Revisions