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User Guide  
Wi-Fi Touchscreen  
Programmable Thermostat  
RTH8500 Wi-Fi Series  
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In the box you will find  
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ꢀ Thermostat  
ꢀ Wallplate (attached to thermostat)  
ꢀ Screws and anchors  
ꢀ Coin cell battery (inside the back  
of the thermostat)  
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ꢀ Quick Start Guide  
ꢀ Thermostat ID Card  
ꢀ Wire labels  
ꢀ User Guide  
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Welcome  
Congratulations on your purchase of a  
Honeywell Wi-Fi touchscreen programmable  
thermostat. When registered to Honeywell’s  
Total Connect Comfort Solutions, you can  
remotely monitor and control the heating and  
cooling system in your home or business—you  
can stay connected to your comfort system  
wherever you go.  
Honeywell’s Total Connect Comfort is the  
perfect solution if you travel frequently, own  
a vacation home, a business or manage an  
Investment property or if you are simply looking  
for peace of mind.  
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This thermostat works with common 24 volt systems such as forced air, hydronic,  
heat pump, oil, gas, and electric. It will not work with millivolt systems, such as a gas  
fireplace, or with 120/240 volt systems such as baseboard electric heat.  
This thermostat contains a Lithium battery which may contain Perchlorate material.  
Perchlorate Material—special handling may apply.  
See www.dtsc.ca.gov/hazardouswaste/perchlorate  
MERCURY NOTICE: Do not place your old thermostat in the trash if it contains  
mercury in a sealed tube. Contact the Thermostat Recycling Corporation at www.  
thermostat-recycle.org or 1-800-238-8192 for information on how and where to  
properly and safely dispose of your old thermostat.  
NOTICE: To avoid possible compressor damage, do not run air conditioner if the  
outside temperature drops below 50°F (10°C).  
Need help?  
Visit wifithermostat.com or call 1-855-733-5465 for assistance before returning the  
thermostat to the store.  
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Table of contents  
Setting filter reminder intervals .................43  
Cleaning the screen..................................44  
Unregistering thermostat...........................45  
Disconnecting Wi-Fi ..................................46  
Special features ........................................48  
Setting functions and options....................51  
About your new thermostat  
Home screen quick reference.....................5  
Preset energy-saving schedules.................6  
Installation  
Installing your thermostat............................8  
Connecting to your Wi-Fi network.............26  
Registering your thermostat online...........31  
Appendices  
Frequently asked questions ......................59  
Message center messages.......................62  
Troubleshooting.........................................65  
Limited warranty........................................71  
Operation  
Setting the clock........................................36  
Setting the fan...........................................37  
Selecting system mode.............................38  
Adjusting program schedules....................39  
Overriding schedules temporarily .............40  
Overriding schedules permanently ...........41  
Setting vacation hold.................................42  
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Features of your Wi-Fi thermostat  
With your new thermostat, you can:  
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ꢀ Connect to the Internet to monitor and control your heating/cooling system  
ꢀ View and change your heating/cooling system settings  
ꢀ View and set temperature and schedules  
ꢀ Receive alerts via email and get automatic upgrades  
Your new thermostat provides:  
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ꢀ Smart Response Technology  
ꢀ Compressor protection  
ꢀ Heat/cool auto changeover  
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Home screen quick reference  
Once your Wi-Fi thermostat is installed, it will display the home screen. Portions of this  
display will change depending on how you are viewing it. To change settings, simply press  
the appropriate area lightly with your finger.  
Message center  
Wi-Fi status  
Inside  
Select fan mode  
Schedule is on (does not  
display when off)  
Select system mode  
Program schedules  
MORE  
Additional settings  
Override schedule  
Set clock  
Lock screen for cleaning  
Unless you change the lighting function, the screen is always lit at low intensity. When you  
touch the screen, the screen brightens.  
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Preset energy-saving schedules  
This thermostat is pre-set with energy-saving program settings for four time periods.  
Using the default settings can reduce your heating/cooling expenses if used as directed.  
Savings may vary depending on geographic region and usage.  
Default Heat Settings  
Default Cool Settings  
WAKE  
70 °  
78 °  
6
:00 am  
LEAVE  
62 °  
70 °  
62 °  
85 °  
78 °  
82 °  
8
:00 am  
RETURN  
6
:00 pm  
SLEEP  
0:00 pm  
1
To change the settings, see pages 39–42.  
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Setting up your thermostat  
Setting up your Wi-Fi programmable touchscreen thermostat is easy. It is preprogrammed  
and ready to go as soon as it is installed and registered.  
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2
3
Install your thermostat.  
Connect it to your home wireless network.  
Register online for remote access.  
Before you begin, you may want to watch a brief installation video.  
®
Use the QR Code at the front of this guide, or go to  
wifithermostat.com/support  
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Installing your thermostat  
You might need the following tools to install this thermostat:  
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ꢀ No. 2 Phillips screwdriver  
ꢀ Small pocket screwdriver  
ꢀ Pencil  
•ꢀ Drill and bits (3/16” for drywall,  
/32” for plaster) (optional)  
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ꢀ Hammer (optional)  
ꢀ Electrical tape (optional)  
ꢀ Level (optional)  
1
Switch OFF power to your  
heating/cooling system.  
or  
Important! To protect your equipment,  
switch OFF the power to your heating/  
cooling system at the breaker box or  
the system switch.  
Circuit  
breaker  
box  
Heating/cooling  
system power  
switch  
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Installing your thermostat  
2
Remove old thermostat faceplate  
and leave wires connected.  
If you have an older thermostat with a  
sealed mercury tube, turn to page 2  
for proper disposal instructions.  
2
a Take a picture of the wire  
connections for later reference.  
2
b If no wire is connected to a  
terminal labeled C or no C  
terminal exists on the old  
thermostat, view the Alternate  
Wiring videos at  
C
wifithermostat.com/videos  
Important! C wire is required and  
is the primary power source for  
your thermostat. Without a C wire,  
your thermostat will not power up.  
Terminal  
designation  
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Installing your thermostat  
3
Label wires.  
Do not label by wire color. Use  
the supplied sticky tags to label  
each wire as you disconnect it.  
Label wires according to the old  
thermostat terminal designations,  
not by wire color.  
Sticky tag  
Blank tags  
Note: If no tag matches a  
terminal designation, write the  
appropriate letter on a blank  
sticky tag.  
4
Remove wallplate.  
Remove the old wallplate from  
the wall after all wires have been  
labeled and disconnected.  
Terminal  
designation  
C
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Installing your thermostat  
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Separate Wi-Fi thermostat and its  
wallplate.  
Finger holds  
Thermostat  
On your new thermostat, grasp the  
finger holds on the top and bottom of  
the wallplate with one hand and the  
thermostat (front) with the other hand.  
Pull pieces apart.  
Wallplate (back view)  
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Installing your thermostat  
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Mount wallplate for Wi-Fi thermostat.  
Mount your new wallplate using  
screws and anchors included with the  
thermostat.  
Wallplate  
If necessary:  
Drill 3/16-in holes for drywall.  
Drill 7/32-in holes for plaster.  
HEAT PUMP  
CONVENTIONAL  
Y2  
RC  
R
RC  
R
L
E/AUX  
W2  
K
W
Y
O/B  
Y
K
Note: You may be able to use your  
existing wall anchors. Hold the wallplate  
up to the existing anchors to check for  
alignment.  
G
G
C
C
Y
W
R
G
C
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Installing your thermostat  
Important! The Wi-Fi thermostat requires a C wire to operate. The C, or common, wire  
brings 24 VAC power to the thermostat. Many older mechanical or battery operated  
thermostats do not require a C wire. If you don’t have a C wire, try:  
•
ꢀ Looking for an unused wire that is pushed into the wall. Connect that wire to C and  
check that it is connected to the 24 VAC common at your heating/cooling system.  
Check the video section at wifithermostat.com  
Note: Not all heating/cooling systems label the 24 VAC common C. Check your system  
manual or contact the manufacturer to find out which terminal is the 24 VAC common.  
View the Alternate Wiring videos at wifithermostat.com/videos  
Wiring  
For conventional heating/cooling systems (natural gas, oil or electric furnace, air  
conditioner), see page 14. See “Glossary” on page 68 for further definition.  
For a heat pump system, see page 15. See “Glossary” on page 68 for further  
definition.  
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Installing your thermostat  
Wiring (conventional system)  
Remove metal jumper  
only if you have both  
R and RC wires  
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A Wire the Wi-Fi thermostat to your conventional system.  
a
Starting with the C Wire, match the sticky tag on the  
wire to the terminal labels.  
HEAT PUMP  
CONVENTIONAL  
You must have a C wire. See page 13.  
b
Loosen screw, insert wire on inside edge of  
terminal, then tighten screw.  
Y2  
RC  
R
RC  
R
R
L
E/AUX  
K
W
W
Y
O/B  
Y
W2  
K
c
Verify wire is firmly secured by gently pulling  
on wire.  
Y
G
G
G
C
C
C
d
e
Repeat steps a–c for all other wires.  
Push any excess wire back into the wall  
opening after all wires are installed.  
Note: The wiring for your  
application might be different  
than the wiring from above.  
f
Continue to page 20.  
Labels don’t match? See alternate  
wiring key on pages 16–17.  
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Installing your thermostat  
Wiring (heat pump system only)  
Labels don’t match? See alternate  
wiring key on pages 18–19.  
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B Wire Wi-Fi thermostat to your heat pump.  
a
Starting with the C Wire, match the sticky tag on the wire to the terminal labels.  
You must have a C wire. See page 13.  
b
c
Loosen screw, insert wire on inside edge of  
terminal, then tighten screw.  
Verify wire is firmly secured by gently pulling  
on wire.  
HEAT PUMP  
RC  
R
R
L
E/AUX  
K
O
AUX  
O/B  
d
e
Repeat steps a–c for all other wires.  
Push any excess wire back into the wall  
opening after all wires are installed.  
Continue to page 20.  
Y
Y
G
G
C
C
f
Note: The wiring for your  
application might be different  
than the wiring from above.  
Note: If old thermostat has separate wires on AUX and E,  
place both wires into the E/AUX terminal. If old thermostat  
has wire on AUX with a jumper to E, place wire on E/AUX  
terminal. No jumper is required.  
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Installing your thermostat  
Alternate wiring (conventional system)  
Use this if your wire labels don’t match the terminal labels.  
CONVENTIONAL  
Note: You must have  
Metal Jumper  
a C wire or equivalent.  
See page 13.  
RC  
Y2  
Y2  
RC  
R
1
2
R
W
Y
W2  
K
W2  
W
Y
3
G
C
G
C
See key to –  
1 3  
on page 17.  
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Installing your thermostat  
Alternate wiring key (conventional system)  
Remove metal jumper connecting R and RC only if you must connect both  
R and RC.  
1
If your old thermostat had both R and RH wires, remove metal jumper.  
Connect the R wire to the RC terminal, and the RH wire to the R terminal.  
2
3
Do not use K terminal. For future use.  
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Installing your thermostat  
Alternate wiring (heat pump system only)  
Use this if your wire labels don’t match the terminal labels.  
HEAT PUMP  
Metal Jumper  
Note: You must have  
a C wire or equivalent.  
See page 13.  
RC  
R
Y2  
RC  
R
1
2
5
L
E/AUX  
K
O
6
7
O/B  
Y
3
4
AUX  
Y
G
G
C
C
3
MCR33530A  
See key to –  
1 7  
on page 19.  
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Installing your thermostat  
Alternate wiring key (heat pump system only)  
1
2
Leave metal jumper between R and RC terminals in place.  
If your old thermostat had both V and VR wires, check wifithermostat.com for help.  
If your old thermostat had separate O and B wires, attach the B wire to the C terminal. If  
another wire is attached to the C terminal, check wifithermostat.com for help. Attach the O wire  
to the O/B terminal. Set System Function 0190 to 0 (see page 55).  
3
If your old thermostat had an O wire and not a B wire, attach the O wire to the O/B terminal.  
4
5
If your old thermostat had separate Y1, W1 and W2 wires, check wifithermostat.com for help.  
This is the system monitor. If the monitor finds a problem, you will see a red light in the upper  
right corner of the thermostat (shines through the cover).  
If old thermostat has separate wires on AUX and E, place both wires into the E/AUX terminal. If  
old thermostat has wire on AUX with a jumper to E, place wire on E/AUX terminal. No jumper is  
required.  
6
7
Do not use K terminal. For future use.  
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Installing your thermostat  
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Install battery.  
Insert the coin cell battery  
(included), observing the  
correct polarity.  
Note: A correctly inserted  
battery will extend about halfway  
out of the battery slot on the  
thermostat, allowing for easier  
removal.  
Thermostat interior  
This battery maintains time and  
date during power outages. It  
does not power the thermostat  
(
C wire required).  
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Installing your thermostat  
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Attach thermostat to wallplate.  
Wallplate  
Align the thermostat to the wallplate  
and then snap into place.  
HEAT PUMP  
CONVENTIONAL  
Y2  
RC  
RC  
L
AUX  
/
E
K
Thermostat  
2
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Installing your thermostat  
1
0 Switch heating/cooling system ON.  
Important!  
1
0a Verify that the C wire