Honeywell T6 Pro Programmable Thermostat

Honeywell-T6-Manual-Thermostat-imageHoneywell T6 Manual – Pro Series Thermostat

Installation Instructions

Package Includes:

  • T6 Pro Thermostat
  • UWP Mounting System
  • Honeywell Standard Installation Adapter (J-box adapter)
  • Honeywell Decorative Cover Plate – Small; size 4-49/64 in x 4-49/64 in x 11/32 in (121 mm x 121 mm x 9 mm)
  • Screws and anchors
  • 2 AA Batteries
  • Installation Instructions and User Guide

Optional Cover Plate installation

NOTE: If Optional Cover Plate is not required, see “UWP Mounting System installation” on next page.
Use the Optional Cover Plate when:

  • Mounting the thermostat to an electrical junction box
  • Or when you need to cover paint gap from old thermostat.
  1. Separate the Junction Box Adapter from the Cover Plate. See Figure 1.
  2. Mount the Junction Box Adapter to the wall or an electrical box using any of the eight screw holes. Insert and tighten mounting screws supplied with Cover Plate Kit. Do not overtighten. See Figure 2. Make sure the Adapter Plate is level.
  3. Attach the UWP by hanging it on the top hook of the Junction Box Adapter and then snapping the bottom of the UWP in place. See Figure 3.
  4. Snap the Cover Plate onto the Junction Box Adapter. See Figure 4.
  5. Before starting, turn the power off at the breaker box or switch. Open package to find the UWP. See Figure 5.
  6. Position the UWP on wall. Level and mark hole positions. See Figure 6. Drill holes at marked positions, and then lightly tap supplied wall anchors into the wall using a hammer. ‒ Drill 7/32” holes for drywall.
  7. Pull the door open and insert the wires through wiring hole of the UWP. See Figure 7.
  8. Place the UWP over the wall anchors. Insert and tighten mounting screws supplied with the UWP. Do not over tighten. Tighten until the UWP no longer moves. Close the door. See Figure 8.

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Power options

Insert R and C wires into designated terminals for primary AC power (C terminal is optional if batteries are installed, but it is recommended). Remove wires by depressing the terminal tabs.

Insert AA batteries for primary or backup power.

Setting Slider Tabs

Set R Slider Tab:

  • Use built-in jumper (R Slider Tab) to differentiate between one or two transformer systems.
  • If there is only one R wire, and it is connected to the R, Rc, or RH terminal, set the slider to the up position (1 wire).
  • If there is one wire connected to the R terminal and one wire connected to the Rc terminal, set the slider to the down position (2 wires).UWP Mounting System

NOTE: Slider Tabs for U terminals should be left in place for T6 Pro models.

Wiring terminal designations


Wiring conventional systems: forced air and hydronics

1H/1C System (1 transformer):

  • R Power [1]
  • Rc [R+Rc joined by Slider Tab] [2]
  • Y Compressor contactor
  • C 24VAC common [3]
  • W Heat relay
  • G Fan relay

1H/1C System (2 transformers):

  • Power (heating transformer) [1]
  • Rc Power (cooling transformer) [1]
  • Y Compressor contactor
  • C 24VAC common [3, 4]
  • W Heat relay
  • G Fan relay

Heat-only System

  • R Power [1]
  • Rc [R+Rc joined by Slider Tab] [2]
  • C 24VAC common [3]
  • W Heat relay

Heat-only System with Fan

  • R Power [1]
  • Rc [R+Rc joined by Slider Tab] [2]
  • C 24VAC common [3]
  • W Heat relay
  • G Fan relay

Heat-only System (Series 20) [5]:

  • R Series 20 valve terminal “R” [1]
  • Rc [R+Rc joined by Slider Tab] [2]
  • Y Series 20 valve terminal “W”
  • C 24VAC common [3]
  • W Series 20 valve terminal “B”

Cool-only System:

  • R Power [1]
  • Rc [R+Rc joined by Slider Tab] [2]
  • Y Compressor contactor
  • C 24VAC common [3]
  • G Fan relay

Heat-only System  (power open zone valve) [5]:

  • R Power [1]
  • Rc [R+Rc joined by Slider Tab] [2]
  • W Valve
  • C 24VAC common [3]

2H/2C System (1 transformer) [6]:

  • R Power [1]
  • Rc [R+Rc joined by Slider Tab] [2]
  • Y Compressor contactor (stage 1)
  • C 24VAC common [3]
  • W Heat relay (stage 1)
  • G Fan relay
  • W2 Heat relay (stage 2)
  • Y2 Compressor contactor (stage 2)


Wire specifications: Use 18- to 22-gauge thermostat wire. Shielded cable is not required.

  1. Power supply. Provide disconnect means and overload protection as required.
  2. Move R-Slider Tab on UWP to the R setting. For more information, see “Setting Slider Tabs” on page 3
  3. Optional 24VAC common connection.
  4. Common connection must come from cooling transformer.
  5. In ISU set Heat system type to Radiant Heat. Set number of cool stages to 0.
  6. In Installer Setup, set system type to 2Heat/2Cool Conventional.

Wiring heat pump systems

Shaded areas below apply only to TH6320U/TH6220U or as otherwise noted.

1H/1C Heat Pump System:

  • R Power [1]
  • Rc [R+Rc joined by Slider Tab] [2]
  • Y Compressor contactor
  • C 24VAC common [3]
  • O/B Changeover valve [7]
  • G Fan relay

2H/1C Heat Pump System [8]:

  • R Power [1]
  • Rc [R+Rc joined by Slider Tab] [2]
  • Y Compressor contactor
  • C 24VAC common [3]
  • O/B Changeover valve [7]
  • G Fan relay Aux Auxiliary heat
  • E Emergency heat relay
  • L Heat pump fault input
Thermostat mounting
  1. Push excess wire back into the wall opening.
  2. Close the UWP door. It should remain closed without bulging.
  3. Align the UWP with the thermostat, and push gently until the thermostat snaps in place.
  4. Turn the power on at the breaker box or switch.Thermostat mounting
System operation settings
  1. Press the Mode button to cycle to the next available System mode.
  2. Cycle through the modes until the required System mode is displayed and leave it to activateHoneywell-T6-Manual-Thermostat-System-operation

NOTE: Available System modes vary by model and system settings.

System modes:

  1. Auto
  2. Heat
  3. Cool
  4. Em Heat
  5. Off
Fan operation settings
  1. Press the Fan button to cycle to the next available Fan mode.
  2. Cycle through the modes until the required Fan mode is displayed and leave it to activate.Honeywell-T6-Manual-Thermostat-Fan-operation

NOTE: Available Fan modes vary with system settings.

Fan modes:

  • Auto: Fan runs only when the heating or cooling system is on.
  • On: Fan is always on.
  • Circ: Fan runs randomly about 33% of the time

Installer setup (ISU)


  1. Press and hold CENTER and buttons for approximately 3 seconds to enter advanced menu.
  2. Press Select to enter ISU.
  3. Press Select to cycle through menu setup options.
  4. Press or to change values or select from available options.Honeywell-T6-Manual-Thermostat-Installer-setup
  5. Press Select and confirm your settings or press Back to ignore changes and return to ISU menu screen to continue editing another setup option.
  6. To finish setup process and save your setting, press Home and return to Home screen.

NOTE: A complete list of all setup (ISU) parameters and options starts below and continues through page 10.

Advanced setup options (ISU)

NOTE: Depending on system settings, not all options may be available.

Advanced setup
Advanced setup
Advanced setup

Installer system test

To perform a System Test:

  1. Press and hold CENTER and buttons for approximately 3 seconds to enter advanced menu.
  2. Use  to  go to TEST. Press Select to enter System Test.
  3. Use to change between Heat, Cool, Fan, Em Heat, or Ver (thermostat version information). Press Select.
  4. Press  to turn stages on one at a time, and press to turn them off.
  5. Use the Home button to exit the System Test.Honeywell-T6-Manual-Thermostat-Installer-system--test

System test            System status



  • Temperature Ranges:
    Heat: 40 °F to 90 °F (4.5 °C to 32.0 °C)
    Cool: 50 °F to 99 °F (10.0 °C to 37.0 °C)
  • Working Ambient Temperature:
    32 °F to 120 °F (0 C° to 48.9 °C)
  • Operating Ambient Temperature:
    37 °F to 102 °F (2.8 °C to 38.9 °C)
  • Shipping Temperature:
    -20 °F to 120 °F (-28.9 °C to 48.9 °C)
  • Operating Relative Humidity:
    5% to 90% (non-condensing)
  • Physical Dimensions in inches (mm) (H x W x D):
    4-1/16” H x 4-1/16” W x 1-5/32” D
    103.5 mm H x 103.5 mm W x 29 mm D

Electrical Ratings



CAUTION: ELECTRICAL HAZARD Can cause electrical shock or equipment damage. Disconnect power before beginning installation.


CAUTION: EQUIPMENT DAMAGE HAZARD Compressor protection is bypassed during testing. To prevent equipment damage, avoid cycling the compressor quickly


CAUTION: MERCURY NOTICE If this product is replacing a control that contains mercury in a sealed tube, do not place the old control in the trash. Contact your local waste management authority for instructions regarding recycling and proper disposal.


Does this work with 24 voltage ?

Yes, it’s a low-voltage (24 VAC) thermostat, compatible with the vast majority of forced air HVAC systems.

Does it switch from heat to cool automatically?

Yes, but “System Changeover” in the ISU menu must be changed from the default value of 0 (“Manual”) to 1 (“Automatic”), then “Auto” can be selected as one of the operating modes using the “Mode” button.

Can I control the thermostat from my phone?

no. need a wyfi stat for that. But is a good thermostat.

I have this thermostat at home right now… Is there a smart variation of it i can swap this out for without messing with wires?

Yes the t6 lyric

Does it work with Alexa ?

This thermostat does not have a wifi connection it will not work with Alexa, phone, or any device. It must be programmed on the thermostat itself by pushing buttons although it is digital. It’s a very nice thermostat and works great.

Does it reset after power failure ?

It has battery back up.

can I schedule the thermostat to turn off at 5 am?

2-programs per day or 4-programs per day, or no programs per day adjustable for 5-1-1, or 5-2days, as far as off and on, can not do that just to the lowest, or highest temp.

Is this thermostat dual fuel

If by dual fuel you mean one source for heat and a different source for A/C, then yes. I have gas heat and electric air on two separate units and have this thermostat controlling both units.

How wide is this unit?

T4 is a basic stat that works on batteries or 24vac, it is no programmable good for milli volt fireplaces, furnaces. T5 does not have emergency heat for heat pumps, t6 has programming capability select able requires 24 vac from furnace. still has batteries just to maintain set back programs

C wire?

You don’t need the C wire on this model as it takes batteries. The wifi model will require a C wire however.

What is the depth of this unit?


Is this the newest model?

I just bought two and this looks like mine. They do work beautifully…

Does it come with a plate to hide the screw holes from my existing thermostat?

Yes, plate is 4-3/4 square.

Is it hard to program

Sometimes annoying. To change one time, cycle or temp program, you have to go through too many program changes. For instance you have to go through separate ac, and heat programs for each step. Temporary or locked permanent temperature changes however are easy.


Customer assistance

For assistance with this product, please visit
Or call Honeywell Customer Care toll-free at 1-800-468-1502.

Honeywell T6 Manual – Pro Series Thermostat – Optimized PDF
Honeywell T6 Manual – Pro Series Thermostat – Original PDF

T6 Installation Instructions [pdf]
T6 Thermostat Manual [pdf]


Honeywell T6 Manual – Pro Series Thermostat
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Join the Conversation


  1. I found the instructions for using thermostat. I had a difficult time simply finding the user manual but could easily find manuals on installing

  2. My thermostat says Unlock then it goes to a screen that says 5. How do I get back to the screen that shows Mode

    1. My thermostat says Unlock and then it goes to a screen that says 5. How to get back to the screen that shows Mode

      Mon thermostat dit Déverrouiller puis il passe à un écran qui dit 5. Comment revenir à l’écran qui affiche Mode

  3. How do you program the thermostat for various temperatures (wake, leave, return, etc) during the day and week?

  4. My unit says “Permanent Hold” . What the heck does that mean? No where in the Manual does it mention this, or many other operating settings and how to use it.

    1. It means it will hold the settings on screen indefinitely. Like an old fashioned tstat. It will not change settings based on schedule. If u want to increase or decrease temperature then u have to do it.

  5. My T6 Pro Programmable Thermostat all of a sudden has displayed a triangle with an exclamation point inside of it. No where in this manual does is say what this symbol is for. Please advise as soon as possible. This symbol is located to the right of the room temperature setting on the screen pad. Thanks!

  6. I have my t6 thermostat programmed ( I think) my question is how do I manually change the temp if it’s to cold or warm? Will I lose the program? How do I go back to the program without a hassle . I am 75 and this is confusing to me ty for nynhelp

  7. My thermostat says Unlock at the bottom. If I select that it then goes to a screen that shows a 5. This seems to be a lockout mode of some kind? Help! All I want to do is program my thermostat! I can not get back to to mode screen.

    1. Emergency Heat, this uses a resistive heating system (at a much greater energy cost) to provide heat. In normal mode, heat is provided by the heat pump system.

  8. how do you change the batteries on the thermostat? Where do you change it. Will this also cut my heat off or does it reset by itself?

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