Lennox S40 Installation And Setup Manual
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Lennox S40 Installation And Setup Manual

Smart thermostat
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Dallas Home
Temp
Status
My Home
TM
72
Feels Like
TM
60%
Heat to
Cool to
68
75
Away
Weather
Lennox
S40 Smart Thermostat
®
508222-01 10/2022
Copyright 2022
Lennox Industries Inc.
Installation and Setup Guide
©
Dallas, Texas, USA

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Questions and answers

Bill
February 11, 2025

Is the s 40 a direct replacement for the 10F81 old Lennox thermostat? Just 4 wires.

0
1 comments:
Mr. Anderson
February 12, 2025

Yes, the Lennox S40 thermostat is a direct replacement for the Lennox 10F81 thermostat with 4-wire standard thermostat wiring. The wires and voltages are the same, making installation simple. However, it is only compatible with Lennox communicating HVAC equipment.

This answer is automatically generated

0
Robert Berg
March 8, 2025

Although my winter schedule is set up for heat setting at 10:30 pm for 18 degrees C, and 22 degree at 7:30 **** , during the night the furnace comes on about 6 **** . The temp in the house is 20 degrees. The Heat setting reads 21 degrees. I then have to manually set the heat to below 20 degrees to turn off the furnace. I have tried all schedules, same thing happens.

0
1 comments:
Mr. Anderson
March 8, 2025

The Lennox S40 thermostat may be turning on the furnace at 6 AM despite a scheduled heat setting of 18°C at 10:30 PM due to the "Start Time Options" feature. This feature allows the system to start heating earlier than the scheduled time to reach the desired temperature by the set time. The default setting is "standard," but it can also be set to "less aggressive" or "more aggressive," which may start the heating process earlier. Adjusting this setting in the thermostat menu may help control when the furnace turns on.

This answer is automatically generated

0
Peter Born
April 23, 2025

When using the cooling mode and the schedule is set for summer the fan cannot be to run continuously. Am I doing something wrong?

0

Related Manuals for Lennox S40

Summary of Contents for Lennox S40

  • Page 1 Dallas Home Temp Status My Home Feels Like Heat to Cool to Away Weather Lennox S40 Smart Thermostat ® 508222-01 10/2022 Copyright 2022 Lennox Industries Inc. Installation and Setup Guide © Dallas, Texas, USA...

  • Page 2: Table Of Contents

    Information ..............38 Multiple Thermostats - Group ID ......17 Installation Checklist..........92 Tests ...............38 Commissioning Using the Thermostat ....17 Index ................95 Diagnostics .............39 Dealer Information ..........17 Installation Report ...........39 General Settings .............17 Connect to Lennox Smart Technician App ....39 Equipment Found Screen ........18...

  • Page 3: Shipping And Packing List

    Module (EIM). Lennox Smart Technician App (Installer) ® Humidity Micro USB with • The free Lennox Smart Technician App allows the installer to commission Sensor Cap Cover BOTTOM VIEW and service the system on most iOS and Android™ devices. Reboot...

  • Page 4: Downloading Lennox Smart Applications

    From the thermostat home screen, go to Menu > Support Services and under desire. Local Lennox Dealer Info verify that all of the fields have been completed. Then select Service Access and enable Remove View and under Remote Lennox Smart Technician App Control select On / Always.

  • Page 5: Wiring Diagrams

    OPTION 1 Figure 3. Lennox Communicating System Wiring Connections using Unshielded (Option 1) or Shielded Wiring (Option 2) Cabling There may be situations where alternate wirings methods may need to be employed. Two options are available to address an inductive voltage issue. If Alert Code 105 (see “Table 20.

  • Page 6: Minimizing Electrical Noise

    C terminal or to second bundle. Figure 5. Minimizing Electrical Noise Lennox Lennox Communicating Communicating Outdoor Unit Thermostat 18/2 Brown Solid CU CL2 Thermostat Wire OPTION 3 Figure 4. Lennox Communicating System Wiring Connections using Separate Unshielded Cable (Option 3)

  • Page 7: Application Specific Wiring Diagrams

    Lennox Communicating Indoor Unit Air Conditioner Air Handler Unit Figure 7. Lennox S40, Communicating Indoor Control (Conventional Figure 6. Lennox S40, Lennox Communicating Air Handler with 24VAC Connections), Relay and HCWHD4 Series Dehumidifiers (1- or 2-Stage) Heat Pump or Air Conditioner...
  • Page 8 Wiring Diagram) In-Zone Thermostats Lennox Communicating Outdoor Unit Lennox See Smart Zoning Installation instruction for damper connection information. Communicating Indoor Unit Figure 8. Lennox S40, Lennox Communicating Indoor and Outdoor Units, Smart Zoning System (Damper Control Module) and Zone Sensors...
  • Page 9 Furnace or Air Handler OPTIONAL DISCHARGE AIR SENSOR 24VAC UV Light Applications: In any Lennox communicating system, the indoor unit will (SEE DAS NOTES) NOT have adequate power to to run the 24VAC UV light application. An additional transformer OPTIONAL OUTDOOR will be required.
  • Page 10 NOTE: Set the communicating thermostat fan mode operation to Circulate and adjust duration to match control ventilation time duration. Figure 10. Lennox S40, Lennox Ventilation Control System (LVCS), Current Sensing Relay, 120VAC Coil Relay, Damper Transformer, Ventilation Dampers and Communicating Indoor Unit (using Non-Communicating Terminals)
  • Page 11 SEE HEPA INTERLOCK KIT FOR INSTALLATION DETAILS (See Lennox Communication LENNOX COMMUNICATING Wiring Diagram) THERMOSTAT OR DAMPER CONTROL MODULE (See Lennox LENNOX Communication COMMUNICATING Wiring Diagram) OUTDOOR UNIT Figure 11. Lennox S40 and HEPA Bypass Filter Interlock Kit and Humidifier...
  • Page 12 OPERATION, CUT R-DS. FLOAT RELAY SWITCH R-DS W914 THERMOSTAT (See Lennox Communication Wiring Diagram) LENNOX COMMUNICATING CONVENTIONAL INDOOR UNIT OUTDOOR UNIT (1 OR 2 STAGE) FLOAT RELAY SWITCH FLOAT SWITCH Figure 12. Lennox S40, Lennox Communicating Indoor Controls and Float Switch...

  • Page 13: Dual Fuel And Ventilation Diagrams

    For additional wiring, please refer to the accessory installation instruction. Use the following procedure for installation of the thermostat wall plate where When using a Lennox Communicating Furnace and conventional heat pump an equipment interface module (EIM) will be require. In addition, ventilation existing thermostat wiring does not exist: (ERV/HRV and Fresh Air Damper will also required an EIM.

  • Page 14: Installing Thermostat To Sub-Base

    2. Detach sub-base from thermostat body. Install subbase with arrow pointing up. 3. Determine the best location to install wall plate. Ideal location should be located away from outside wall, direct sunlight or discharge air vents. The thermostat should typically be installed at least 5 feet up from the floor. 4.

  • Page 15: Commissioning Using The Lennox® Smart Technician

    Return to the thermostat and select the right arrow to continue. The Lennox Smart Technician App is available for both IOS 11.0 or higher (App Store) and Android 9.0 or higher (Google Play). 6. The next screen is the Connect Thermostat with Lennox Smart Technician App.

  • Page 16: Commissioning Screens

    Servicing using the Lennox Smart Technician App Not Connected English Franҫais Welcome - Select To use Lennox Smart Technician App as a service tool, the commissioning Language Español of the system must have already been completed. S40-XXXXXXXXX will appear. It should match the thermostat ID...

  • Page 17: Multiple Thermostats - Group Id

    Multiple Thermostats - Group ID IMPORTANT Multiple S40 thermostats in a home can be assigned to a group (up to nine If after applying power to the thermostat a “System Under Test” screen appears, groups with up to five (5) thermostats in each group). All thermostats in a group it could indicate either the system is under reconfiguration or is unable to can communicate with other thermostats in the same group over a single 2.4...

  • Page 18: Equipment Found Screen

    Humidifiers would appear as either EIM-Furnace or EIM-Air Handler. When using an EIM the outdoor unit may be either a Lennox communicating or any Options are: standard 24VAC non-communicating unit.

  • Page 19: Reminders

    • Cooling Circulation Airflow (blue) which includes total, assigned, minimum and maximum airflow. If the home will have multiple S40 thermostats then they all MUST be on the Reminders same 2.4GHz Home Wi-Fi network in order to connect to each other. Do not use 5 GHz.

  • Page 20: Wi-Fi Terminology

    NOTE: The thermostat can connect to a home wireless router that uses up to with wireless communications. Some examples of other devices that could 32 characters in the access point name (visible or hidden). DO NOT interfere are: connect to a guest access point. •...

  • Page 21: Service Center

    The following is a complete list of all possible parameters listed under System. Temp Deadband Range is 3 to 9°F (1.67 to 5.0°C). Default is 3°F (1.67°C). Parameters actually available are dependent on the Lennox communicating Adjustments are in increments of 1°F (0.56°C). equipment type detected and non-communicating equipment added.
  • Page 22 Table 5. Thermostat Parameters Table 5. Thermostat Parameters Parameter Parameter (In alphabetical Description (In alphabetical Description order) order) Adjustments are in increments of 1%. This value can automatically be Setting used to prevent the heat pump from heating the structure. Auto affected by adjusting other parameters.
  • Page 23 (ramping up and down) adjusting to lower setting will correct. Range is 0 to 5 electric heat stages. Default is 2. Adjustments are in Stages During Lennox advises not to make changes to this setting without first increments of 1. (Lennox Variable...
  • Page 24 When staged heating is chosen, the • Normal is when the heat pump will heat the home will providing S40 thermostat allows you to choose between 1, 2, 3 and 4 stages of (Lennox Variable the highest efficiency.
  • Page 25 Heating Cycles to maintain the settings of the S40 thermostat. (This governs how Per Hour many cycles per hour the system will try to run when it needs to run Options are unlocked, partially locked and locked. Default is Screen Locked at less than minimum capacity.
  • Page 26 Adjustments are in increments of 0.125°F (0.07°C). Decrement Slope This setting determines the temperature differential limit between the smart room sensor and the S40 thermostat. Setting range is 2 to SSP Cooling Cancel Range is -0.75 to 0.0°F (-0.42 to 0.0°C). Default is -0.25°F (-0.14°C).
  • Page 27 Stage HSP = Heat Set Point NOTE: Lennox variable capacity systems will stage electric heat N = number of 30 second intervals to the target program set Differentials point but not on differentials. It will use the thermostat PI logic to...
  • Page 28 Table 5. Thermostat Parameters Table 5. Thermostat Parameters Parameter Parameter (In alphabetical Description (In alphabetical Description order) order) Ventilation Control Mode - timed (default) Parameter range is -20 to 55ºF. Default is 0ºF. Can be adjusted in increments of 5ºF. Parameter range is 0.0 - 60.0 minutes.
  • Page 29 Ventilation Outdoor Condition Override - Enabled component configurations. These parameter values are automatically adjusted to the specific hardware configuration. See Lennox Smart Zoning system installation instruction for minimum CFMs for specific Parameter range is 60 to 115ºF. Default is 100ºF. Can be adjusted in indoor units.
  • Page 30 (See table 9 in Range is 40 to 60°F (4.44 - 15.56°C). Default is 45°F (7.22°C). for Cooling Lennox Smart Zoning installation instruction for minimum CFMs for Adjustments are in increments of 1°F (0.56°C). Zone 1 through 4 specific indoor units).
  • Page 31 Table 6. Thermostat Parameters - Heat Cool Stages Locked In Table 6. Thermostat Parameters - Heat Cool Stages Locked In Heating - Heat Pump with Electric - 3 Stage Heating - Dual Fuel - 3 Stages (2 compressor / 1 backup) (2 compressor / 1 backup OR 1 compressor / 2 backup) 1st stage Stages...

  • Page 32: Air Handler

    Air Handler Table 7. Air Handler Parameters Parameter Description Table 7. Air Handler Parameters Heating Indoor The range is 0 - 5 seconds. Default is 0 seconds with an Parameter Description Blower On Delay incremental adjustment of 1 second. Range of operation of the indoor blower during high cooling Provides information concerning unit code, language support, High Cooling operation.

  • Page 33: Furnace

    Furnace Table 8. Furnace Parameters Parameter Description Table 8. Furnace Parameters Options for this setting are fixed CFM or fixed DAT (discharge air Parameter Description temperature). Default is dependent on equipment type match-up. Fixed CFM is selected as the Heating Airflow Control Type This screen provides information on unit code, language supported, (parameter default selection), the circulator will operate at a CFM equipment type name, unit model number, unit serial number, unit...

  • Page 34: Heat Pump

    (Single and Two-Stage Heat Pump will count down the delay in minutes 1 to 5 minutes. The sequence Lennox Communicating is time remaining and a dash, and will repeat that cycle (5, 4, 3, 2 Outdoor Units) and 1) until the count down is complete. If the delay timer is change Table 9.
  • Page 35 • After the first two cycles, the furnace will run for 60 seconds ON (Lennox Variable then cycle OFF for 90 seconds. The range is 450 - 2150 CFM. Default is dependent on unit capacity Capacity Heat with an incremental adjustment of 25 CFM.

  • Page 36: Air Conditioner

    25 CFM. the remaining filter life through continuous sampling, but will not (Lennox Variable Thermostat values shown are defaults. This value can be adjusted use filter tests to determine filter life. The control will: Capacity Air up or down to meet each application requirements.

  • Page 37: Add/Remove Equipment

    Status types that can be displayed are High, Medium and Basic Smart Devices Network Cleanliness (Most Economical) The Lennox Smart Devices Network can only be created by using the Lennox ® Monitor Status Smart Technician Application . This indicates the Bluetooth signal strength between the monitor RSSI Signal Strength and the S40 thermostat or wireless extender if used.

  • Page 38: Lennox Wireless Extender

    This indicates the Bluetooth signal strength between the monitor touch the left arrow at the top left side of screen to return to the Dealer Control RSSI Signal Strength and the S40 thermostat or wireless extender if used. Center. Extender Information IMPORTANT Model Number Model number of device.

  • Page 39: Diagnostics

    Dehumidification Setting Options the service app to the thermostat. The provided Quick Start Guide has a QR code that can be scanned to download the Lennox Smart Technician App to • Basic — Recommend when the air outside is not too humid.

  • Page 40: Overcooling

    Overcooling Table 17. Dehumidification Control Modes of Operations Mode of Slide bar adjust with a range of 0°F to 4°F (-17.8 to -15.5°C). Only available Option Description Operation when Max or Climate IQ is selected. Staged Outdoor Unit: At the end of a cooling call, if the humidity is above the set Dehumidification Set Point point by a certain amount (Basic to Precision Threshold Available...

  • Page 41: Lennox Smart Zoning

    • Lennox communicating variable speed indoor unit and communicating or The S40 ventilation function is only a turn on - turn off feature. All CFMs must be non-communicating (conventional) two-stage outdoor unit (four zones adjusted from the HRV/ERV unit. The ventilation function can be controlled by maximum supported).

  • Page 42: Fresh Air Damper

    Fresh Air Damper Ventilation Control Modes This option is used to control a damper connecting outside air to the return Thermostat ventilation CFM parameters are to be adjusted only after the HRV/ plenum of the system. When a fresh air damper style of ventilation is added ERV set up is completed and the CFMs are known.
  • Page 43 Table 18. Ventilation Control Modes Fresh Air Ventilation Control Mode Speed Speed Speed Speed Damper ASHRAE Number of Bedrooms Ventilation Outdoor Condition Override - Enabled Ventilation High Outdoor Temperature Limit (60 to 115°F, default is 100°F) Ventilation Low Outdoor Temperature Limit (–20 to 55°F, default is 0°F) Ventilation High Outdoor Dew Point Limit (45 to 80°F, default is 55°F)

  • Page 44: Notifications (Service And Alert Codes)

    To expand a specification notification to access a more detail description of the alert code, press the down arrow to expand the description. Table 19. Alert Code Priority Condition Visibility Notifications Displayed or Email Notifications Sent Lennox ® Displayed for...

  • Page 45: Soft Disable

    3000 Filter 1 is display by double horizontal lines on seven segment display. 3001 Filter 2 • On Lennox damper control module and EIM the green LED will blink 3 3002 Humidifier pad seconds on and 1 second off. 3003...

  • Page 46: Alert Codes

    Equipment Listing > Reset and select Reset All Equipment. This will allow the system to auto-detect any Lennox communicating components attached. Thermostat did not find an indoor unit. Make sure there is an Lennox communicating indoor unit on the system.
  • Page 47 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 48 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 49 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 50 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 51 (device) is unable to communicate. • S40 - Open Dealer Service Center - Select the notification icon, select All, review alert code details to determine which device’s low voltage wiring is experiencing a communication issue. Review both active and cleared alerts.
  • Page 52 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 53 • Damper control module will operate in central mode only until proper voltage is restored or frequency distortion is resolved • If connected to Lennox Smart Zoning system, set damper control module transformer jumper to system transformer. Check for proper wiring. Replace 40VAC furnace transformer with 70VAC transformer. Re-commission system.
  • Page 54 There is a hardware problem on a system component control. There is a control hardware problem. • In system using Lennox Smart Zoning, the system will remain in non-zone mode (all dampers open) for five minutes after priority condition no longer exist.
  • Page 55 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 56 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 57 Lennox has not received any complaints of no heat situations associated with this operating condition. It has been determined that occasionally the fault clears itself and the alert code is not stored in the IFC or Lennox communicating thermostat.
  • Page 58 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 59 • Check for non-functioning zone dampers. the field will need to manually activate the NOTE: Limit trips will place the Lennox Smart Zoning system into non-zone mode. zoning. NOTE: See ACC-14-01 for further details. A discharge air-temperature is high. Perform the following: •...
  • Page 60 The furnace limit switch has been open for more than three minutes. The system will go into Watchguard mode. In Lennox Smart Zoning systems, the limit trips will place the system into central mode. • Check for high gas pressure.
  • Page 61 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 62 • Check for high duct static. There is a discharge air temperature sensor issue. • Confirm there is no short or open circuits in the Lennox communicating thermostat connections to any of the other components in the communicating system. Automatically clears •...
  • Page 63 • Replace system component (device) control. reset. If error is applicable to the Lennox variable capacity outdoor units, the outdoor control will need to be replaced. The heat pump configuration link is not cut on the air handler control.
  • Page 64 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 65 • The system will not operate. • Dealer has cut the W914 jumper (Dehum, Harmony III) on the Lennox furnace control. • The thermostat monitors the DS terminal in the furnace for power and if the link has been cut then power will be lost to DS.
  • Page 66 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 67 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 68 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 69 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 70 OU Compressor Top Service Soon clears when error is • Lennox Variable Capacity Outdoor Units: Check to ensure that one of the wires from the top cap switch Cap Switch Open corrected. has not been disconnected from one of the TP terminals on the outdoor control. Reconnect wire if disconnected.
  • Page 71 • Inverter LEDs will flash code 21. • If the unit is a Lennox variable capacity heat pump, this error may occur entering or exiting a defrost cycle as the compressor restarts after the 30 second compressor shift delay. If the unit was manufactured prior to serial number 5817F and has frequent alert code 427, then compare the inverter part number to the latest part number listed in the unit repair parts.
  • Page 72 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 73 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 74 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 75 433, which typically occurs during start-up. > If the system is connected to the Internet, the Lennox outdoor control can be updated over the Internet. Make sure the software “auto update” is enabled. The software “auto update” can be toggled to prompt the Lennox server to update the thermostat which will update the Lennox outdoor control.
  • Page 76 • If the unit is locked out with a service urgent alert code 434, reset the system by cycling the outdoor unit Service OU Inverter alert code 434, reset power off and back on. Then cycle the indoor power off (24VAC to the Lennox outdoor control) and then Soon/Service Communication Error the system by first back on.
  • Page 77 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 78 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 79 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 80 Urgent Lockout and restart. • Outdoor unit will stop. The Lennox variable capacity unitary control (outdoor control) has incorrect appliance unit size code selected. Automatically clears OU MUC Unit Code • Check for proper configuring under unit size code used for outdoor unit (see unit configuration guide or in...
  • Page 81 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 82 At the Lennox communicating thermostat, only zone 1 screen will be available. NOTE: The Lennox communicating thermostat will display the alert code as “Problem (Zoning Control)”. ZS Zone 4 Temp Email notifications will describe the issue as “ Zone “X” Temp Sensor Problem.
  • Page 83 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 84 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 85 • Typically the thermostat will send a command to the unknown device and place it in a soft disable state. Thermostat Lost Automatically clears The Lennox communicating control with the soft disable state will indicate so as follows: Service 65539...
  • Page 86 • Blinking blue LED will appear if not communicating with thermostat. Only on versions with mag-mount. • Typically the thermostat will send a command to the unknown device and place it in a soft disable state. Not applicable. The Lennox communicating control with the soft disable state will indicate so as follows: Information Automatically clears...
  • Page 87 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 88 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 89 Table 21. Lennox S40 Smart Thermostat Alert Codes and Troubleshooting E2A=Errors to Action, GF= Gas Furnace, AH=Air Handler, IU=Indoor unit (GF or AH), HP=Heat Pump, AC=Air Conditioner, OU=Outdoor Unit (AC or HP), PA=Pure Air S, ZA=Zone system, SRS=Smart Room Sensor, TS=Thermostat , IAQ- IAQ Monitor and WE=Wi-Fi Extender...
  • Page 90 XX: Unknown Wireless when the system 80005 Service Soon • Move the wireless BLE device closer to the thermostat or add a Lennox Wireless Extender to increase the Device Found. detects that the issue wireless coverage area. no longer exists.
  • Page 91 Possible loose or mis-wired connections or two zone sensors are assigned the same zone number. Two cause the double dashes will be displayed on the S40 thermostat for indoor temperature and/or zone sensor. The system will dashes to appear. Service Soon go into central mode.

  • Page 92: Installation Checklist

    Is the Wi-Fi connected? Has the homeowner downloaded the Lennox Thermostat application from either Google Play or IOS App Store to their mobile devices? Is the Lennox Dealer account number or your main shop phone number been added to the dealer information screen? If applicable, has the air handler’s electric heat strips been commissioned? If not, commissioning of heat strips must be performed.

  • Page 95: Index

    Discharge Air Sensor (DATS) Gas Heat Control Mode (SLP98 Auto Dehumidification only) 24 Integral Gain 23 Lennox Smart Zoning 41 Overcooling Threshold 22 Gas Heating Activation Temp Offset 23 Lock In 2nd Stage HP by Outdoor Automatic Max Defrost 34...
  • Page 96 Smart Alert Enable 26 (SLP98V only) 25 Signal Strength Indicator 20 Gas Heating Step Change PI Gain (SLP98V only) 25 Smart Devices HP Heating Cycles Per Hour 25 Smart Air Quality Monitor 37 HP Heating Steady State PI Gain 25 Zone 1 through 4 Smart Devices Network 37 HP Heating Step Change PI Gain 25...

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