Lennox ComfortSense™ 3000 Series Non-Programmable Thermostat

Introduction

The Lennox ComfortSense™ 3000 Series model L3011C is an easy-to-use, non-programmable electronic thermostat offering excellent temperature control with a large, readable display. It features a programmable filter change reminder and a system check indicator to alert users to potential equipment service needs. This thermostat is designed for non-heat pump, single-stage heat/single cool applications compatible with gas or electric furnaces.

These instructions are intended as a general guide and do not supersede local codes. Consult local authorities before installation. Check equipment for shipping damage and contact the carrier immediately if damage is found.

This document describes the operation of the Lennox model L3011C thermostat. For installation and wiring instructions, refer to the separate installation manual.

Initial Thermostat Power-up

Upon initial power application, the thermostat display activates all segments momentarily as part of its initialization process. Within seconds, it transitions to the Home screen, typically displaying an indoor room temperature of 70°F. The display includes indicators for ROOM temperature, SETPOINT, FILTER status, SERVICE alerts, FAN mode (AUTO/ON), and SYSTEM mode (HEAT/COOL/OFF/EMG. HEAT). A pale blue backlight activates with key presses and turns off after 8 seconds of inactivity.

Home Screen Display

The Home screen shows the current indoor room temperature and the setpoint temperature. The SYSTEM box indicates the current operating mode, with HEAT mode being the default. The display backlight activates with any key press and remains on for 8 seconds.

Heating Control

The HEAT button, located behind the thermostat's access door, is used to enable or disable heat mode. When the thermostat is in OFF mode, pressing HEAT enables it, indicated by 'HEAT' in the SYSTEM box. If the thermostat is already in heat mode, pressing HEAT disables it, showing 'OFF' in the SYSTEM box.

Heating Demand: When the thermostat is in heat mode and the room temperature falls below the setpoint, a heating demand is initiated. The thermostat activates the heating equipment, indicated by a flame icon [?] in the SYSTEM box. Heating operation continues until the room temperature reaches the setpoint, at which point the flame icon disappears. The heating equipment runs for a minimum of 3 minutes per demand cycle.

Cooling Control

The COOL button, also behind the access door, enables or disables cool mode. Pressing COOL when in OFF mode enables cooling, shown as 'COOL' in the SYSTEM box. Pressing COOL when in cool mode disables it, displaying 'OFF' in the SYSTEM box.

Cooling Demand: In cool mode, if the room temperature exceeds the setpoint, a cooling demand occurs. The thermostat activates the cooling equipment, indicated by a snowflake icon [❄️] in the SYSTEM box. Cooling operation stops when the room temperature drops below the setpoint, and the snowflake icon disappears. Cooling equipment is activated for a minimum of 4 minutes per demand cycle, with a 5-minute lockout period after a demand is satisfied to prevent short cycling.

Adjusting Temperature Setpoint

The temperature setpoint can be adjusted using the UP [↑] and DOWN [↓] arrow keys located to the right of the display. Each press changes the setpoint by 1°F. The current setpoint is displayed below the room temperature. The HOME screen reappears approximately 8 seconds after the last key press.

Fan Control

The FAN button, behind the access door, controls fan operation. It can be set to continuous fan mode (ON) or auto fan mode (AUTO). In continuous mode, the fan runs constantly, indicated by 'ON' in the FAN box. In auto mode, the fan operates only when heating or cooling equipment is running, indicated by 'AUTO' in the FAN box. A fan icon [?] appears in the FAN box when the fan is running.

Filter Reminder

The thermostat includes a filter reminder feature, configurable for 1, 3, 6, or 12-month intervals. The SETTINGS button, behind the access door, is used to set this interval. After the set period elapses, the 'FILTER' reminder is displayed. To reset the reminder after changing the filter, press and hold the SETTINGS button for 4 seconds.

Service Indicator

When abnormal equipment operation is detected, the 'SERVICE' indicator will flash in the upper-right corner of the screen, signaling the need for service by a qualified technician. This indicator appears under specific conditions, such as prolonged Y1 terminal activation combined with specific R or C terminal connections.

Thermostat RESET

In cases of abnormal thermostat behavior, such as after an electrical storm or power outage, the thermostat can be reset to its default settings. The RESET button is a recessed, unlabeled button located behind the access door, below the SETTINGS button. Use a paper clip or pencil tip to press it. After pressing RESET, the thermostat reverts to the default settings listed in Table 1.

Default Thermostat Settings

Technical Specifications

• Thermostat Type: Electronic non-programmable thermostat for 1H/1C, gas or electric heat, non-heat pump, non-power robbing applications.
• Power Supply Range: 18VAC - 30VAC (24VAC nominal), 60Hz.
• Temperature Display:
  • Scale: Fahrenheit or Celsius (user selectable via DIP switches).
  • Range: 35°F (2°C) to 99°F (37°C).
  • Resolution: 1°F (1°C).
  • Accuracy: ±1°F.
• Temperature Measurement Range:
  • Scale: Fahrenheit.
  • Range: 35°F to 99°F.
  • Resolution: 0.5°F.
  • Accuracy: ±1°F.
  • Field Offset: ±3°F (via DIP switches).
  • Sampling Method: Temperature measurements sampled every 15 seconds; displayed temperature is the average of the last four measurements.
• Temperature Setpoint Range:
  • Setting range: 50°F (10°C) to 90°F (32°C).
  • Setting resolution: 1°F (1°C).
• Fan Control: AUTO or ON modes, compatible with gas or electric heat via DIP switches.
• I/O Relays: Latching type for minimal power consumption (HEAT/COOL output, FAN output, SERVICE input).
• Equipment Protection Timers: Minimum Compressor OFF time (5 min), Compressor ON time (4 min), Furnace ON time (3 min), minimum furnace cycle time (6 min), minimum compressor cycle time (6 min). These timers can be overridden by pressing HEAT or COOL buttons for 4 seconds.
• Over-Temperature Protection: Thermal mechanical switch opens W1 at 93°F ±6°F.

Power Loss/Recovery

Thermostat memory retains settings (setpoint, modes, filter reminder, timers) for a minimum of 24 hours during a power loss. After 24 hours, settings revert to defaults. For memory retention, power must be applied for at least six consecutive hours prior to a power loss.

LCD Backlight

The LCD backlight activates for 8 seconds when any key is pressed. It may briefly activate during electrical disturbances but will return to normal operation afterward.

Thermostat Operating and Storage Conditions

• Operating Conditions: 35°F to 105°F, 5% to 90% RH.
• Storage Conditions: -40°F to 185°F, 5% to 95% RH.

Thermostat Output Table

NOTE - X = output is activated with 24VAC.