Lenox Lennox Merit Series Gas Furnace Upflow/Horizontal air discharge, ML180UHE Service

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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 opera- tion, serious injury, death, or property damage. Before servicing, disconnect all electrical power to furnace.

When servicing controls, label all wires prior to dis- connecting. Take care to reconnect wires correctly. Verify proper operation after servicing.

At the beginning of each heating season, a qualified techni- cian should check the system as follows:

Blower

Check the blower wheel for debris and clean if necessary. The blower motors are prelubricated for extended bearing life. No further lubrication is needed.

WARNING

The blower access panel must be securely in place when the blower and burners are operating. Gas fumes, which could contain carbon monoxide, can be drawn into living space resulting in personal inju- ry or death.

Filters

All ML180UHE filters are installed external to the unit. Fil- ters should be inspected monthly. Clean or replace the fil- ters when necessary to ensure that the furnace operates properly. Replacement filters must be rated for high veloc- ity airflow. Table 1 lists recommended filter sizes.

Flue And Chimney

1 − Check flue pipe, chimney and all connections for tight- ness and to make sure there is no blockage.

2 − Check unit for proper draft. Electrical

1 − Check all wiring for loose connections.

2 − Check for the correct voltage at the furnace (furnace operating). Correct voltage is 120VAC + 10%.

3 − Check amp−draw on the blower motor with blower ac- cess panel in place.

Unit Nameplate__________Actual__________

Cleaning the Heat Exchanger and Burners

NOTE − Use papers or protective covering in front of the fur- nace during cleaning.

1 − Turn off both electrical and gas power supplies to fur- nace.

2 − Remove flue pipe and top cap (some applications top cap can remain) from the unit.

3 − Label the wires from gas valve, rollout switches, prima- ry limit switch and make−up box then disconnect them.

4 − Remove the screws that secure the combustion air in- ducer/pressure switch assembly to the collector box. Carefully remove the combustion air inducer to avoid damaging blower gasket. If gasket is damaged, it must be replaced to prevent leakage.

5 − Remove the collector box located behind the combus- tion air inducer. Be careful with the collector box gas- ket. If the gasket is damaged, it must be replaced to prevent leakage.

6 − Disconnect gas supply piping. Remove the four screws securing the burner manifold assembly to the vestibule panel and remove the assembly from the unit.

7 − NOX units only − Remove screw securing NOX insert. Remove NOX insert. See figure 38.

8 − Remove screws from both sides, top and bottom of vestibule panel.

9 − Remove heat exchanger. It may be necessary to spread cabinet side to allow more room. If so, remove five screws from the left side or right side of cabinet. See figure 39.

10 −Backwash using steam. Begin from the burner opening on each clam. Steam must not exceed 275°F.

11− To clean burners, run a vacuum cleaner with a soft brush attachment over the face of burners. Visually inspect in- side the burners and crossovers for any blockage caused by foreign matter. Remove any blockage. Figure 37 shows burner detail.

12−To clean the combustion air inducer visually inspect and using a wire brush clean where necessary. Use com- pressed air to clean off debris and any rust.

13−Reinstall heat exchanger in vestibule. (Replace the five screws in the cabinet from step 10 if removed).

14−NOx units only − Replace NOx inserts.

15−Reinstall collector box and combustion air assembly. Reinstall all screws to the collector box and combustion air inducer. Failure to replace all screws may cause leaks. Inspect gaskets for any damage and replace if necessary.

16−Reinstall burner box and manifold assembly.

17−Reconnect all wires.

18−Reconnect top cap and vent pipe to combustion air in- ducer outlet.

19−Reconnect gas supply piping.

20−Turn on power and gas supply to unit.

21−Set thermostat and check for proper operation.

22−Check all piping connections, factory and field, for gas leaks. Use a leak detecting solution or other preferred means.

23−If a leak is detected, shut gas and electricity off and repair leak.

24−Repeat steps 24 and 26 until no leaks are detected.

25−Replace access panel.

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Contents Table of Contents Installation Instructions ML180UHETOP View Unit Dimensions − inches mmGas Valve Parts ArrangementMake−Up Box Heat Exchanger Combustion Air Inducer Burner BoxShipping and Packing List Safety InformationML180UHE Gas Furnace 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 Typical Horizontal Application Horizontal Application Installation Clearances Top LeftRight End BottomDuct System FiltersLeft Side Vent Discharge VentingUpflow Position Top Vent DischargeSide Vent Discharge − no modifications necessary Horizontal Left Position Horizontal Right PositionHorizontal Left Position Side Vent DischargeVent 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 Gas supply piping should not allow more than 0.5W.C. drop Ers or straps. Install a drip leg in vertical pipe runs to− In some localities, codes may require the installation Gas PipingRight−Side Air Discharge Horizontal ApplicationLeft−Side Air Discharge Electrostatic Discharge ESD Interior MAKE−UP BOX InstallationElectrical Thermostat Designations ML180UHE Schematic Wiring Diagram and Sequence of Operation Integrated Control Typical ML180UHE Field Wiring DiagramUnit Start−Up For Your Safety Read Before LightingHigh Altitude Gas Pressure AdjustmentGAS Meter Clocking Chart Proper CombustionManifold Pressure Settings at all Altitudes Other Unit AdjustmentsNo Jumper Heat FAN-OFF Time in Seconds1345 1380995 975 115 945230 Single Side Return Air − Air volumes in bold require fieldOrder to maintain proper air velocity 640 1940 420 1750 310Electrical SHOCK, Fire Or Explosion Hazard Service−045 and −070 units ML180UHE BURNER, Combustion AIR Inducer AssemblyHeat Exchanger Removal −090, −110 −135 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 Drain Line Cooling ModeTemperature Rise Unit Operation

Lennox Merit Series Gas Furnace Upflow/Horizontal air discharge, ML180UHE specifications

The Lenox ML180UHE is a reliable and efficient gas furnace that falls within the Lennox Merit Series. This model is designed for upflow or horizontal air discharge, making it versatile for various installation requirements. With its robust construction and advanced technology, the ML180UHE is ideal for homeowners seeking a dependable heating solution that combines comfort and efficiency.

One of the main features of the ML180UHE is its impressive 80% Annual Fuel Utilization Efficiency (AFUE) rating. This efficiency means that 80 cents of every dollar spent on fuel is used to heat your home while minimizing waste. This furnace is equipped with a multi-speed blower motor that enhances the overall air circulation in your home, providing consistent temperatures and improved comfort.

The ML180UHE features a durable heat exchanger made of high-quality materials, which ensures longevity and reliable performance. The design of the heat exchanger maximizes heat transfer efficiency, allowing the furnace to quickly warm your home while also maintaining optimal efficiency levels throughout its lifespan.

Lennox has integrated advanced technologies into the ML180UHE to enhance its operation and user experience. The unit is compatible with a variety of thermostats, including Lennox's innovative iComfort S30 Smart Thermostat, allowing for easy temperature control and programming capabilities. This smart technology can learn your preferences, optimize energy usage, and enable remote access through a smartphone app.

In addition to its energy efficiency, the ML180UHE offers quiet operation, making it an excellent choice for residential environments. The well-insulated cabinet helps to reduce noise levels, providing a peaceful indoor atmosphere.

Installation and maintenance are simplified with the ML180UHE due to its compact design and accessible components. The furnace is designed to fit into tight spaces, allowing for flexible installation options. Regular maintenance is uncomplicated, ensuring that homeowners can keep the unit running at peak performance with minimal effort.

Overall, the Lennox ML180UHE gas furnace provides users with a reliable, efficient, and quiet heating solution. With its combination of advanced technology, durable design, and ease of use, it is an excellent choice for anyone looking to enhance the comfort of their home while optimizing energy consumption.