LENNOX CORE CONTROL SYSTEM - Unit Controller Application Guide - Installation and Service Safety

Oct 17, 2026

Installation and service safety requirements for the Lennox CORE Control System unit controller are presented, emphasizing that improper installation, adjustment, alteration, service, or maintenance may cause property damage, personal injury, or loss of life. Guidance covers CORE and wireless controller functionality, including connections, inputs/outputs, app operations, room sensor modes, alarms, data, service, and settings, as well as operational topics such as protection delays, sensor options, outdoor fan control, dehumidification, economizer, DCV, and related control behaviors.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages120

Reading Time5 h 2 min

AccessFree to download

M4 Unit Controller Description

Unit Sizes

Add-on Controllers

Lennox CORE Unit Controller Connections, Inputs / Outputs, Jumpers, and LEDs Locations

W4 Wireless Controller

Wireless Gateway

CORE Service App

Wireless Sensor

Wireless Repeater

Cloud Firmware Updates

CORE Service App - Unit Operations

CORE Service App Menu Selection Overview

System Overview - Room Sensor Mode

Active Alarms

CORE Service App General Menu + User Preference

CORE Service App RTU Menu

Data

Service

Settings

Main Controller Operations

Control Type - Thermostat

System Mode - Room Sensor

Room Sensor Primary Modes

Unit Component Operation - Protection, Delays and Switches

Compressor Protection and Delays

Gas Units Burner Protection and Delays

Miscellaneous Components

Gas Heat Operation - Gas Units

Electric Heat Operation

Sensors

Temperature Sensors Provided With Unit

Room Sensor Optional

Relative Humidity Sensor Optional

Carbon Dioxide Sensor Optional

Supply Static Pressure Sensor Optional

Enthalpy Sensor Optional

Outdoor Fan Operations during Various Ambient Conditions

High Ambient Conditions

Normal Ambient Conditions

Low Ambient Conditions

Compressor / Fan Configurations

Low Ambient Outdoor Fan Control and Cycling

Dehumidification Operations

Humiditrol+ Dehumidification Operation (Humiditrol Reheat)

Third Party Digital Input to Control Dehumidification

Selecting Minimum Low and Minimum High Damper Positions

Enhanced Dehumidification Operations

Dehumidification in Wired Thermostat Mode

Enhanced Dehumidification in Room Sensor Mode

Enhanced Dehumidification with Relative Humidity Sensor

Enable or Disable Enhanced Dehumidification Mode

Power Exhaust Operations

Enabling Feature

Control

Operation Based on Various Options

Economizer Operations

General

Enabling Economizer and Settings

Damper Feedback Calibration

Damper Operation During Free Cooling

Free Cooling Compressor Lockout Mode and Low Ambient Set Point

Outdoor Air Suitable for Free Cooling

Enthalpy Set Point

Free Cooling Damper Maximum Position

Minimum Damper Position

Closing Damper and Calibration

Motorized Outdoor Air Damper

Economizer Checkout

Demand Control Ventilation (DCV) Operations

General

Default Operation

Maximum and Minimum DCV Damper Settings

LENNOX® CORE CONTROL SYSTEM (UNIT CONTROLLER) APPLICATION GUIDE 485115 4/2022 | 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) or service agency | Table of Contents 1. M4 Unit Controller Description ............................. 4 1.1. Unit Sizes .............................................................. 4 1.2. Add-on Controllers ................................................ 4 1.4. Lennox CORE Unit Controller-Connections, Inputs / Outputs, Jumpers, and LEDs Locations ............. 6 2. W4 Wireless Controller-Connections, Buttons and LEDs .................................................. 8 2.1. Wireless Gateway ................................................ 8 2.2. CORE Service App ............................................... 8 2.3. Wireless Sensor (21L07) ...................................... 8 2.4. Wireless Repeater (21L09) ................................... 9 2.5. Cloud Firmware Updates ...................................... 9 3. CORE Service App-Unit Operations ................. 10 3.1. CORE Service App Menu Selection Overview.... 10 3.2. System Overview-Room Sensor Mode ............. 10 3.3. Active Alarms .......................................................11 3.4. CORE Service App General Menu + User Preference ...........................................................11 3.5. CORE Service App RTU Menu ............................11 3.6. Data .................................................................... 21 3.7. Service ................................................................ 22 3.8. Settings ............................................................... 26 4. Main Controller Operations ................................. 28 4.1. Control Type-Thermostat .................................. 28 4.2. System Mode-Room Sensor ............................ 30 4.3. Room Sensor Primary Modes: ............................ 30 5. Unit Component Operation-Protection, Delays and Switches ............................................ 33 5.1. Compressor Protection and Delays .................... 33 5.2. Gas Units Burner Protection and Delays ........... 34 5.3. Miscellaneous Components ............................... 35 5.4. Gas Heat Operation—Gas Units ........................ 37 5.5. Electric Heat Operation ...................................... 37 6. Sensors ................................................................. 38 6.1. Temperature Sensors-Provided With Unit ........ 38 6.2. Room Sensor-Optional ..................................... 38 6.3. Relative Humidity Sensor-Optional ................... 38 6.4. Carbon Dioxide (Indoor Air Quality) SensorOptional............................................................... 39 6.5. Supply Static Pressure Sensor-Optional........... 39 6.6. Enthalpy Sensor-Optional ................................. 39 7. Outdoor Fan Operations during Various Ambient Conditions ............................................. 40 7.1. High Ambient Conditions..................................... 40 7.2. Normal Ambient Conditions ................................ 40 7.3. Low Ambient Conditions .................................... 40 7.4. Compressor / Fan Configurations ...................... 40 7.5. Low Ambient Outdoor Fan Control and Cycling.. 42 8. Dehumidification Operations .............................. 45 8.1. Humiditrol+ Dehumidification Operation—(Humiditrol Reheat) ............................................. 45 8.2. Third Party Digital Input to Control Dehumidification ................................................. 45 8.3. Selecting Minimum Low and Minimum High Damper Positions................................................ 46 9. Enhanced Dehumidification Operations ..

FAQs

What are the safety risks if the Lennox CORE control system is improperly installed or maintained?

Improper installation, adjustment, alteration, service, or maintenance can cause property damage, personal injury, or loss of life.

Who must perform installation and service for the system?

Installation and service must be performed by a licensed professional HVAC installer (or equivalent) or a service agency.

What functionality does the guide cover for the CORE and wireless controllers?

The guide covers unit controller descriptions and wiring details, wireless controller connections and components, and CORE Service App operations including menus, room sensor modes, alarms, data, service, and settings.

Oct 17, 2026

Upload by AditGamingID