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

Page 40

Troubleshooting: Heating Sequence of Operation (Continued)

HEATING SEQUENCE CONTINUED

 

 

NORMAL HEATING MODE

 

 

 

 

 

 

 

ABNORMAL HEATING MODE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15-SECOND COMBUSTION AIR INDUCER PREPURGE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INITIATED BY CLOSED PRESSURE SWITCH.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LED FLASHES CODE 13 −

 

 

 

YES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

 

 

 

 

 

 

 

 

LOW LINE VOLTAGE.

 

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

 

 

 

IGNITOR WARM-UP −− 20 SECONDS.

 

 

 

 

 

IS VOLTAGE ABOVE 70 VOLTS?

 

 

ONCE VOLTAGE IS ABOVE

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

75 VOLTS, HEATING

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

 

SEQUENCE RESTARTS.

 

 

 

4-SECOND TRIAL FOR IGNITION.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GAS VALVE OPENS. IGNITOR ENERGIZED FOR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FIRST 3 SECONDS OF THE TRIAL.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INDOOR BLOWER OFF.

 

 

 

 

 

 

 

NO

 

 

YES

 

 

 

NO

 

HAS CONTROL FAILED TO SENSE FLAME FOR

 

 

 

 

 

 

 

 

 

FIVE CONSECUTIVE TRIES DURING A SINGLE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FLAME STABILIZATION PERIOD.

 

 

 

 

 

 

 

 

HEAT DEMAND?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4 SECONDS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FLAME RECTIFICATION CURRENT

 

 

 

 

 

LED SIGNAL WATCHGUARD FAILURE CODE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHECK. CAN FLAME BE PROVEN WITHIN

 

 

 

 

 

 

 

WATCHGUARD MODE. GAS VALVE OFF.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4 SECONDS AFTER GAS VALVE OPENS?

 

 

 

 

 

 

 

COMBUSTION AIR INDUCER OFF.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(0.5 microamps)

 

 

 

 

 

 

 

INDOOR BLOWER OFF WITH DELAY

 

 

 

 

 

 

 

 

 

 

YES

 

 

NO

 

 

IS 60-MINUTE RESET PERIOD COMPLETE?

 

 

YES

NO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FLAME PRESENT?

 

 

 

 

HAS CONTROL RESET IGNITION

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SEQUENCE FOUR TIMES?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

YES

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LED FLASHES CODE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

LED FLASHES CODE 4 − LOW FLAME

 

 

 

 

7 − PRIMARY LIMIT

 

 

 

 

 

 

 

 

 

 

 

OPEN. GAS VALVE,

 

 

FLAME SIGNAL 1.5 MICROAMPS OR GREATER?

 

 

 

 

 

 

 

SIGNAL.

 

 

 

 

COMB. AIR INDUCER

 

 

 

 

 

 

 

(Does not affect operation of control)

 

 

 

 

 

 

YES

 

 

 

 

 

 

 

 

 

 

AND INDOOR BLOW-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ER OFF. LEDs SIG-

 

 

INDOOR BLOWER ON

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NAL LIMIT SWITCH

 

 

AFTER 30−SECOND DELAY

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LED FLASHES CODE 7 − PRIMARY LIMIT OPEN

 

 

OPEN UNTIL MAIN

 

 

YES

 

 

 

 

 

 

 

 

 

POWER IS

 

 

 

 

 

 

 

 

 

 

GAS VALVE DE−ENERGIZED.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

INTERRUPTED OR

 

 

 

 

 

NO

 

 

COMBUSTION AIR INDUCER DE−ENERGIZED.

 

 

 

 

 

 

 

 

 

 

 

T’STAT IS CYCLED

 

 

PRIMARY LIMIT SWITCH CLOSED?

 

INDOOR BLOWER ON UNTIL SWITCH CLOSES.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OFF/ON FOR 1 SEC.

 

 

 

 

 

 

 

 

 

 

 

 

LIMIT SWITCH CLOSED?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

 

 

 

 

 

 

MINIMUM. 60−MINUTE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WATCHGUARD PE-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

RIOD STARTS AT

 

 

 

 

 

 

 

 

 

 

 

 

HAS PRIMARY LIMIT RESET

 

 

 

 

 

 

 

 

 

 

 

 

 

TIME LIMIT CLOSES.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

 

 

 

 

 

TIME EXCEEDED 3 MINUTES?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IS 60−MIN. PERIOD

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

 

 

 

 

COMPLETE?

 

 

 

 

 

 

NO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LED FLASHES CODE 8 − ROLLOT SWITCH OPEN.

 

 

 

 

ROLLOUT SWITCH CLOSED?

 

 

 

 

 

 

 

GAS VALVE POWER OFF. COMBUSTION AIR INDUCER POWER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YES

 

 

 

 

 

 

 

 

ON. INDOOR BLOWER ON SEQUENCE HOLDS UNTIL ROLLOUT

 

 

 

 

 

 

 

 

 

 

 

 

SWITCH IS RESET AND MAIN POWER IS INTERRUPTED OR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NO

 

 

 

THERMOSTAT IS CYCLED OFF/ON FOR 1 SEC. MINIMUM.

 

 

 

 

 

 

 

 

 

 

COMBUSTION AIR PRESSURE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SWITCH CLOSED?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

YES

THERMOSTAT DEMAND SATISFIED.

YES

LED SLOW FLASH.

YES

COMB. AIR INDUCER CONTINUES 5-SECOND

POST PURGE AFTER T’STAT DEMAND IS SATISFIED. INDOOR AIR BLOWER COMPLETES SELECTED

DELAY BEFORE SHUTTING OFF.

HAS PRESSURE SWITCH OPENED 5 TIMES

 

 

 

LED FLASHES

 

IN THE SAME HEAT DEMAND?

 

 

 

 

 

 

 

CODE 10

 

 

 

 

 

 

 

NO

 

YES

1 HR PRESSURE

 

GAS VALVE DE−ENERGIZED. COMBUSTION AIR

 

SWITCH

 

 

WATCHGUARD

 

INDUCER ON. INDOOR BLOWER OFF WITH

 

 

 

MODE

 

DELAY. HAS CAB PRESSURE SWITCH CLOSED

 

 

 

 

 

WITHIN 2.5 MINUTES?

 

 

 

 

 

 

 

YES

 

NO

 

 

 

 

 

 

 

 

 

 

5-MINUTE PRESSURE SWITCH

 

 

 

 

 

WATCHGUARD MODE.

 

 

 

 

 

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Contents Installation Instructions ML180UHE Table of ContentsUnit Dimensions − inches mm TOP ViewParts Arrangement Make−Up Box Heat Exchanger Combustion Air InducerBurner Box Gas ValveML180UHE Gas Furnace Safety InformationShipping and Packing List 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 Horizontal Application Installation Clearances Top Left RightEnd Bottom Typical Horizontal ApplicationFilters Duct SystemVenting Upflow PositionTop Vent Discharge Left Side Vent DischargeHorizontal Left Position Horizontal Right Position Horizontal Left PositionSide Vent Discharge Side Vent Discharge − no modifications necessaryVent 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 130 Carbon Monoxide Poisoning Hazard Ers or straps. Install a drip leg in vertical pipe runs to − In some localities, codes may require the installationGas 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 Typical ML180UHE Field Wiring Diagram Integrated ControlFor Your Safety Read Before Lighting Unit Start−UpGas Pressure Adjustment GAS Meter Clocking ChartProper Combustion High AltitudeOther Unit Adjustments Manifold Pressure Settings at all AltitudesHeat FAN-OFF Time in Seconds No Jumper1380 995975 115 945 1345Single Side Return Air − Air volumes in bold require field Order to maintain proper air velocity640 1940 420 1750 310 230Service Electrical SHOCK, Fire Or Explosion HazardML180UHE BURNER, Combustion AIR Inducer Assembly Heat Exchanger Removal−090, −110 −135 units −045 and −070 unitsPlanned Service Repair Parts ListIntegrated Control Diagnostic Codes RED LEDNormal Heating Mode Abnormal Heating Mode Heating Sequence of OperationHeating Sequence Normal Cooling Mode Abnormal Cooling Mode Cooling Sequence of OperationContinuous FAN Sequence of Operation Start−Up & Performance Check List Cooling Mode Temperature RiseUnit Operation Drain Line

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.
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