Honeywell T8112 User Manual

PRODUCT DATA
® U.S. Registered Trademark
Copyright © 1996 Honeywell Inc. • All Rights Reserved
T8112
Programmable Thermostat
GENERAL
The T8112 Programmable Thermostat provides energy
savings for single-stage heating and cooling applications
while providing reliable, precise temperature control.
FEATURES
• HEAT-OFF-COOL system switch.
• AUTO-ON fan switch.
• Separate programs for weekdays and weekends
(5 day/2 day).
• Digital LCD display.
• Easy to program and install.
• Precise temperature control.
• Four daily energy saving programs.
• Compatible with most 24 Vac standing pilot, gas
electronic ignition, oil or central electric systems.
• Requires two AA alkaline batteries.
• LCD flashes
bAt Lo indicating low battery power.
• Isolated heating/cooling circuits.
Contents
General ............................................................................... 1
Features .............................................................................. 1
Specifications ...................................................................... 2
Ordering Information ........................................................... 2
Installation ........................................................................... 3
Programming the Thermostat ............................................. 6
Checkout and Settings ........................................................ 7
Troubleshooting .................................................................. 8
68-0170

Honeywell T8112 Specifications

General

Display	Digital
Stages	1 Heat / 1 Cool
Mounting	Wall Mount
Type	Programmable
Temperature Range	40°F to 90°F
Power Source	Battery
Load Type	Resistive
Maximum Current	1.0A
Switch Action	SPST

Summary

Key Features

System Switch

Controls the heating, cooling, or off state of the system.

Programmable Schedules

Allows different temperature programs for weekdays and weekends.

System Compatibility

Works with various heating and cooling system types.

Product Specifications

Model and Description

Identifies the T8112 model and its function for heating/cooling.

Setpoint Range

Defines the adjustable temperature range for heating and cooling.

Mounting Method

Describes how the thermostat is mounted onto a wall plate.

Installation Guide

Electrical Safety Warning

Crucial warning about disconnecting power to prevent electrocution.

Mounting Plate Installation

Step-by-step instructions for installing the mounting plate.

Wiring Guidelines

General rules and references for wiring the thermostat.

System Compatibility Chart

Lists compatible system types for the T8112 thermostat.

Wiring Installation Caution

Wiring Safety Precaution

Emphasizes disconnecting power before any wiring is done.

2-Wire Heat-Only Wiring

Wiring diagram for a 2-wire heat-only system.

3-Wire Cool-Only Wiring

Wiring diagram for a 3-wire cool-only system.

Thermostat Back Adjustments

Adjusting System On-Time

Guidance on adjusting system on-time for optimal performance.

High Efficiency Furnace Adjustment

Specific adjustment for high efficiency furnaces.

Programming the Thermostat

Setting Current Time and Day

Steps to set the current time and day on the thermostat.

Setting Heating Program

Instructions for programming the heating schedule.

Setting Cooling Program

Instructions for programming the cooling schedule.

Operating and Making Changes

Temporary and Hold Temperature Adjustments

How to temporarily adjust or indefinitely hold temperature settings.

Checkout and Settings

System Checkout Procedures

Procedures for testing heating and cooling system operations.

Troubleshooting Common Issues

Power and Display Issues

Resolving problems with the display not powering on or battery indicators.

Heating and Cooling Activation Failures

Diagnosing and fixing issues with heating or cooling system startup.

System Cycling and On-Time Problems

Addressing frequent cycling and incorrect system on-time durations.