Total comfort temperature management with Smart Response™ Technology.
Congratulations! You made a smart choice by purchasing your new Honeywell thermostat; the smart thermostat that

  • Keeps you comfortable by automatically calculating exactly when the furnace or air conditioning should go on to have the house at the desired comfort temperature by the time you wake up or return home.
  • Saves the maximum amount of energy and money by automatically remembering to adjust the temperature when you leave home or go to sleep.
  • Provides the ultimate in comfort and convenience. It comes preprogrammed. You can use the preprogrammed schedule, or set your own.

This manual answers many of the questions that can arise as you become familiar and comfortable with your Honeywell thermostat — the state of the art in home comfort controls.

Read these instructions carefully. Failure to follow these instructions can damage the product or cause a hazardous condition.

Honeywell CT8602 Table of Contents

Step 1. Prepare for Installation ................... 5
Step 2. Remove Old Thermostat ................ 6
Step 3. Mount thermostat Wallplate ........... 7
Step 4. Wire Wallplate Terminals ............... 8
Step 5. Install the Batteries ....................... 9
Step 6. Set Fan Operation Switch ............. 10
Step 7. Mount the Thermostat ................... 11
Step 8. Customize Your Thermostat ........... 11
Step 9. Set the Clock ............................... 13
Step 10. Programming .............................. 14
Step 11. Operating Your Thermostat ........... 17
Step 12. Set the Fan and System Switches  19
If You Have a Problem ............................... 19
Smart Response™ Technology ...................... 21
Wiring Diagrams ....................................... 22



  • Check Table 1, the compatibility chart, to make sure the thermostat is compatible with your system. If your system
    is not compatible, call Honeywell Customer Relations Center, toll-free, 1-800-468-1502.

System Type

Compatibility with CT8602

Gas — Standing Pilot


Gas — Electronic Ignition


Gas-fired Boilers


Gas —750 Millivolt Heat onlyb


Oil-Fired Boilers


Oil-Fired Furnace


Electric Furnace


Electric Air Conditioning


Baseboard Electric (120/240 line volt)c


Single Stage Heat Pump


Multistage Heat Pumps/Multistage Equipment


a Compatible with 2-wire Honeywell and Taco zone valves. Not compatible with 3-wire zone valves or 2-wire White Rodgers no. 1361 zone valves.
b Millivolt system must be heat only.
c Not compatible with any 120/240 volt system.

Package Contents

  • Thermostat •
  • Wallplate •
  • Screws and anchors
  • Wiring labels •
  • 3 Energizer® AA batteries •
  • Owners manual

Tools Required

  • • Screwdriver
  • Drill


  • Test your heating and cooling systems to make sure they work properly. If either system does not work, contact your local heating/air-conditioning dealer. To avoid compressor damage, do not operate the cooling system when outdoor temperature is below 50°F (10°C).
  • Turn off power to the system at the furnace or the fuse/circuit breaker panel.
  • Carefully unpack your new thermostat and wallplate. Save package of screws, instructions, and receipt.
  • Remove the cover from the old thermostat. If the cover does not snap off when pulled firmly from the bottom, check for a screw or screws used to lock on the cover.
  • Loosen the screw or screws holding the thermostat to the wallplate and lift the thermostat away.
  • Disconnect the wires from the old thermostat. As you disconnect each wire, attach the enclosed labels with the old terminal designation. If there are only two wires, they do not need to be labeled. Wrap the wires around a pencil as shown to keep them from falling back into the wall.

Honeywell CT8602 Special Installations

Read this section if you are replacing:

  • Clock thermostat with separate wires for the clock.
  • Thermostat with six or more wires connected to it.
  • Thermostat in a heating only system with three wires.

Replacing a Clock Thermostat that has C or C1 Clock Terminals

If you are replacing a Honeywell Chronotherm® Thermostat, you may find one or two wires going to the C or C1 clock terminals on the Chronotherm wiring wallplate. Do not allow them to touch, or you can damage the transformer. Disconnect the wires and wrap them separately using electrical tape. Do not wrap them together. Place the wires where they will not interfere with the operation of the new thermostat. Record the colors and terminal designation
labels of the remaining wires.

Replacing a Thermostat that has Six or More Wires

If there are six or more wires (excluding clock wires attached to terminals), you probably have a variation of a multistage heat pump or other multistage system. This thermostat is not compatible with multistage systems, so return the product to the place of purchase. If you have questions regarding this thermostat please visit our web site at, or call the 24-hour automated information line at 1-800-468-1502.

Replacing a Thermostat that has Three Wires

If you have three wires for a heating only system and can operate the fan using the fan ON switch this thermostat works with your system. However, some hot water (zoned) heating systems also have three wires. Your thermostat will work only if you install an isolating relay on these systems. For details, call your local heating and/or cooling contractor.


  • Separate the wallplate from the thermostat by placing your thumb or fingers between the bottom of the wallplate and the thermostat, and pulling the wallplate up and away from the thermostat. See illustration at right.
  • Position the wallplate on the wall. Level the wallplate for appearance if desired. Use a pencil to mark the two mounting holes that best fit the application.
  • Remove the wallplate from the wall. Drill two 3/16 in. holes in wall (if drywall) as shown. For materials such as plaster or wood, drill 7/32 in. holes where marked. Gently, tap the (provided) anchors into the drilled holes until they are flush with the wall.
  • Reposition the wallplate over the holes. Pull the wires through the wiring opening. Loosely insert mounting screws into each of the holes.
  • Level the wallplate if desired. Thermostat functions properly when not level.
  • Tighten mounting screws.

Readmore and Download Honeywell CT8602 PROGRAMMABLE THERMOSTAT Manual

Title : Honeywell CT8602 PROGRAMMABLE THERMOSTAT Manual
Format : PDF
Pages : 24 Pages
Language : English
File Size : 3 MB


Honeywell CT8602 Manual

Download PDF