Lennox ML180UHV Series - User Manual

©
2019 Lennox Industries Inc.
Dallas, Texas, USA
507946-01
08/2019
ML180UHV
SERIES
GAS FURNACE
WARNING
Improper installation, adjustment, alteration,
service or maintenance can cause property damage,
personal injury or loss of life. Installation and service
must be performed by a licensed professional
HVAC installer or equivalent, service agency, or the
gas supplier.
WARNING
FIRE OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly
could result in serious injury, death, or
property damage.
Do not store or use gasoline or other ammable
vapors and liquids in the vicinity of this or any
other appliance.
Installation and service must be performed
by a qualied installer, service agency or the
gas supplier.
WHAT TO DO IF YOU SMELL GAS:
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any
phone in your building.
• Leave the building immediately
• Immediately call your gas supplier from a neighbor’s
phone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the re
department.
USER’S INFORMATION
MANUAL

Summary

ML180 UHV Parts Identification

Safety Instructions

General Safety Precautions

Handling mechanical equipment, keeping area clear, airflow, chemical storage, and return air usage.

Asphyxiation and CO Hazard

Ensuring leak-free exhaust vent, annual inspection, and carbon monoxide detector recommendations.

Explosion Hazard - LP Gas

Warning about LP/propane gas leaks, odorant loss, and the use of leak detectors.

Start-Up & Operation Information

Operating the Gas Valve

Step-by-step instructions for safely operating the gas valve on the furnace.

Turning Off Gas to the Unit

Procedure for safely shutting off the gas supply to the furnace for service.

Filters and Maintenance

Filter Information and Replacement

Details on furnace filters, recommended sizes, and replacement guidelines.

Furnace Maintenance Procedures

Annual inspection and cleaning of furnace components by a qualified technician.

Blower Maintenance

Instructions for checking and cleaning the blower wheel for optimal performance.

Service Troubleshooting Checklist

Common checks to perform before calling a service technician for issues.

Safety Precautions and Planned Service

Unit Safety Checks and Indicators

Identifying potential problems through sounds, odors, and visible signs of malfunction.

Flood Damage Warning

Critical warning against using flood-damaged furnaces due to extreme safety risks.

Annual Furnace Maintenance Schedule

Detailed checklist for seasonal professional inspection and service requirements.

System Test and Operation Check

Performing general system tests and verifying operating parameters for functionality.

Repair Parts List

Overview

1. Function Description
2. Usage Features
3. Maintenance Features

This document provides user information for the Lennox ML180UHV Series Gas Furnace, a heating appliance designed for residential use. It emphasizes safety, proper operation, and maintenance to ensure efficient and reliable performance.

Function Description

The Lennox ML180UHV Series Gas Furnace is a forced-air heating system that uses natural gas or propane to generate heat. It is equipped with a SureLight® ignition system, which automatically lights the burners when the thermostat calls for heat, eliminating the need for manual ignition. The furnace draws in combustion air, mixes it with gas, and ignites the mixture in the burners. The hot gases then pass through a heat exchanger, transferring heat to the circulating indoor air without mixing with it. A blower motor then distributes the heated air throughout the building's ductwork. The furnace is designed with safety devices to protect against malfunctions, such as an integrated control system, pressure switch, and flame rollout switches, which monitor operation and shut down the unit if unsafe conditions are detected.

Usage Features

Operating the ML180UHV furnace involves simple steps, primarily controlled by a thermostat. To initiate heating, the thermostat is set to the desired temperature. The furnace's automatic ignition system then takes over, lighting the burners and beginning the heating cycle. The gas valve, equipped with a control switch, allows for easy on/off operation, though users are cautioned to only use their hand to move the switch and never force it. The unit is designed to be user-friendly, with most operational aspects handled automatically once the thermostat is set.

The manual provides clear instructions for starting up the furnace, including setting the thermostat to its lowest setting, turning off electrical power, accessing the gas valve, and moving the gas valve switch to the "OFF" position for a five-minute purge before moving it to "ON." This sequence ensures any accumulated gas is cleared before ignition. Similarly, instructions for turning off the gas to the unit are provided, emphasizing safety by first setting the thermostat to the lowest setting, turning off electrical power, and then moving the gas valve switch to "OFF."

A critical usage feature highlighted is the importance of not setting the thermostat below 60°F (16°C) in heating mode. Doing so can reduce the number of heating cycles and potentially damage the unit, which may not be covered by the warranty. This guidance helps users maintain the furnace's longevity and efficiency.

The furnace is designed to operate with various filter sizes, and the manual provides a table detailing the appropriate side return and bottom return filter dimensions for different cabinet widths (14-1/2", 17-1/2", 21", 24-1/2"). This allows users to select the correct filters for their specific unit, which is crucial for maintaining good indoor air quality and furnace efficiency.

Maintenance Features

The Lennox ML180UHV Series Gas Furnace requires regular maintenance to ensure safe and efficient operation. The manual strongly recommends that installation and service be performed by a licensed professional HVAC installer or equivalent, service agency, or the gas supplier. This is a recurring theme throughout the document, underscoring the complexity and potential hazards associated with gas appliances.

Annual Furnace Maintenance: The manual outlines a comprehensive annual maintenance checklist to be performed at the beginning of each heating season, and to comply with the Lennox Limited Warranty. This includes:

• Electrical Checks: Inspecting wiring for loose connections, checking voltage at the indoor unit, and measuring indoor motor amperage.
• Mechanical Checks: Checking the condition of the belt and shaft bearings (if applicable).
• Gas System Checks: Inspecting all gas pipe and connections for leaks.
• Filter Maintenance: Checking the cleanliness of filters and changing them monthly as needed.
• Burner and Heat Exchanger: Checking the condition and cleanliness of burners and the heat exchanger, and cleaning them if necessary. The heat exchanger integrity should be evaluated per the AHRI heat exchanger inspection procedure.
• Blower Assembly: Checking the cleanliness of the blower assembly, housing, blower wheel, and blower motor, and cleaning them if necessary.
• Combustion Air Inducer: Inspecting and cleaning the combustion air inducer.
• Combustion Air Supply: Ensuring sufficient combustion air is available to the furnace, and that fresh air grilles and louvers are properly sized, open, and unobstructed.
• Venting System: Inspecting the furnace venting system to ensure it is in place, structurally sound, without holes, corrosion, or blockage, and that it slopes upward away from the furnace as per the National Fuel Gas Code.
• Ductwork: Inspecting the furnace return air duct connection for sealing, and checking for air leaks on supply and return ducts, sealing where necessary.
• Cabinet Insulation: Checking the condition of the furnace cabinet insulation and repairing it if necessary.
• Combustion Analysis: Performing a complete combustion analysis during the furnace inspection to ensure proper combustion and operation.
• CO Detectors: Verifying the operation of CO detectors and replacing batteries as required.

System Test: After maintenance, a general system test is recommended to check operating functions such as start-up and shut-off. This includes:

• Ignition System: Checking the operation of the ignition system, inspecting and cleaning the flame sensor, and checking microamps before and after.
• Controls and Safety Devices: Checking the gas valve, flame sensor, and temperature limits.
• Airflow Settings: Verifying that system total static pressure and airflow settings are within specific operating parameters.
• Gas Meter Clocking: Clocking the gas meter to ensure the unit is operating at the specified firing rate, and checking supply and manifold pressures.

Safety Precautions: The manual also details several safety precautions that double as maintenance indicators. Users are advised to shut down the unit and contact a Lennox dealer if they notice:

• Unfamiliar Sounds: Repeated new or unfamiliar sounds during operation, which may indicate poorly performing burners.
• Unusual Odors: Indicating improper operation or components operating in abnormal conditions.
• Visible Malfunctions: Such as unusual amounts of condensate on windows, visibly burnt components, or unusual dirt/rust accumulations on the vent pipe or in the unit.
• Flu-like Symptoms: Headache, nausea, fatigue, or dizziness, which could be symptoms of carbon monoxide exposure, especially if symptoms are exaggerated at home but subside away from the house.

The document also includes a critical warning about flood-damaged furnaces, stating that if any part has been underwater, the furnace is extremely dangerous and attempts to use it can result in fire or explosion. In such cases, a licensed professional service technician must inspect the furnace and replace all gas controls, control system parts, electrical parts, or the entire furnace if deemed necessary.

The repair parts list provided in the manual is also a maintenance feature, guiding users or technicians on where to obtain replacement parts. It specifies that all service must be done by a licensed professional installer or service agency, or the gas supplier, reinforcing the need for expert intervention for repairs.

Lennox ML180UHV Series Specifications

General

Model	ML180UHV Series
Type	Gas Furnace
AFUE Rating	80%
Stages	Single-stage
Ignition Type	Hot Surface Ignition
Cabinet Type	Upflow/Horizontal
Heat Exchanger Material	Aluminized Steel
Fuel Type	Natural Gas
Warranty	5-Year Limited Parts, 10-Year Heat Exchanger
Dimensions	17.5 inches