Lennox SignatureS
tat 81M26 User Manual

Page 1
E2007 Lennox Industries Inc.
Dallas, Texas, USA
Table of Contents
SignatureStatt Thermostat 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Date Code & Serial Number 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Features 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Home Screen & Main Menu 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Programming the Thermostat 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heating and Cooling Cycles 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Humidification 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dew Point Control 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dehumidification 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Humiditrol
®
Accessory 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing Time of Day / Day of Week 11. . . . . . . . . . . . . . . . . . . . . . . .
Cycling the Fan 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
User Settings and Options 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Change Temperature Settings 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Vacation Mode 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installer Settings 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remote Outdoor Sensor 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display Lights 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Memory Protection 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EPA ENERGYSTAR
®
Recommended Setpoints 21. . . . . . . . . . . . . . .
Resetting Program to Factory Conditions 21. . . . . . . . . . . . . . . . . . . . .
Thermostat−specific Information 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flow Diagrams 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wiring Diagrams 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PROGRAMMING AND
APPLICATION GUIDE
SignatureStatt Thermostat
CONTROLS
505,232M
06/07
Supersedes 2/07
81M26 shown
NOTE − This thermostat is equipped with automatic compressor protection
to prevent potential damage due to short cycling or extended power out-
ages. The short cycle protection provides a 5−minute delay between heat-
ing or cooling cycles to prevent the compressor from being damaged.
Shipping and Packing List
1 − SignatureStatt thermostat
1 − Outdoor temperature sensor
Litho U.S.A.

Lennox SignatureS
tat 81M26 Specifications

General

Brand	Lennox
Model	SignatureS tat 81M26
Category	Thermostat
Language	English

Summary

CONTROLS

Shipping and Packing List

Features

Outdoor Temperature Sensor

Measures and displays outdoor temperature for dew point control and system optimization.

L Input

Notifies user of equipment failure via a resistor, LED, and voltage regulator.

Compressor Short Cycle Protection

5-minute timer prevents compressor damage from short cycling or power outages.

Date Code & Serial Number

Home Screen and Main Menu

Main menu options

Lists the eight options available in the main menu, accessed via the menu button.

Programming the Thermostat

Programming for Full Week or Work Week

Programming Day-by-Day

Detailed steps for programming individual days or copying settings between days.

Heating and Cooling Cycles

Determining if Heating or Cooling is ON

How the thermostat display indicates active heating or cooling modes and system status.

Humidification

Humidification Modes

Explains BASIC and PRECISION modes for humidification based on system conditions.

Adjust Humidification Level

Humidifier Maintenance Interval

Notifies users about required humidifier maintenance after 6 months of H terminal activity.

Humidification Sensor Fault

Describes fault conditions for the humidification sensor and their indication.

Dew Point Control

Turn on and Adjust Dew Point Control

Steps to enable and adjust dew point control using outdoor temperature and user settings.

Dehumidification

Dehumidification Modes

DEHUMIDIFY MODE Screen

Steps to select and adjust dehumidification modes (BASIC, PRECISION).

Humiditrol® Accessory

SignatureStat™ thermostat operation with Humiditrol® enabled

Configuration for Humiditrol operation, requiring an outdoor sensor.

Calculating maximum allowable overcooling in cooling-only mode

Other Humiditrol® Accessory Notes

Changing Time of Day / Day of Week

Cycling the Fan

Fan Settings

Options for controlling the fan: ON, AUTO, and INTERMITTENT modes.

Fan Program

User Settings and Options

SHOW SET TEMP setting

Option to display setpoint temperature on the HOME screen.

°F or °C setting

Allows selection of temperature display format (Fahrenheit or Celsius).

12 or 24 hour setting

Allows selection of time display format (12-hour or 24-hour).

EVENTS/DAY setting

Allows selection of number of daily events (2 or 4) for programming.

Differential and delay settings

Settings to determine stage demand timing and delays for multistage systems.

Heating and cooling limits

Security settings

Change Temperature Settings

Brief Temperature Change

Temporarily adjusts temperature setting for 3 hours or until next programmed event.

Hold Settings Menu

Change Temperature Permanently

Sets an indefinite temperature hold, requiring RESUME PROGRAM to return to schedule.

Change Temperature Temporarily

Holds temperature for up to 24 hours, cancelling automatically.

Setting Vacation Mode

Installer Settings

SYSTEM SETUP

Selects the system type (furnace, heat pump) the thermostat controls.

1ST STAGE HEATING

AUXILIARY HEAT

BALANCE POINTS

RESIDUAL COOL

AUTO CHANGEOVER / AUTOCHANGE DEAD BAND

ENERGY EFFICIENT RECOVERY

HUMIDITROL

SECURITY CODE

CONTACT INFORMATION

SERVICE INT

SERVICE MONITOR MENU

Sets criteria for service messages based on system run time or calendar days.

REMINDER

Sets reminder period in hours or days for system/filter service.

TEMP OFFSET

Remote Outdoor Sensor

Display Lights

Memory Protection

EPA ENERGYSTAR® Recommended Setpoints

Resetting Program to Factory Conditions

Thermostat-Specific Information

81M26-1 Stage Heat / 1 Stage Cool, Heat Pump without Auxiliary Heat, or Non-Heat Pump

Details LED indicators, fan operation, and terminal designations for 81M26 models.

Thermostat "Off" Mode

Describes thermostat operation when in the OFF mode, including inactive terminals.

81M27-2 Stage Heat & Cool, Non-Heat Pump

81M28-2 Stage Heat & Cool Heat Pump

Wiring Diagrams