Honeywell T8635L User manual

169-1332—3
USER’S GUIDE
T8635L Microelectronic Communicating
Programmable Thermostat
69-1332-3

269-1332—3

369-1332—3
CONTENTS
USING THIS GUIDE .......................................................................................................................................... 5
FEATURES ........................................................................................................................................................ 6
KEYBOARD AND DISPLAY DESCRIPTION .................................................................................................... 7
Keyboard ............................................................................................................................................................ 7
Display ............................................................................................................................................................... 7
ADAPTIVE INTELLIGENT RECOVERY™ CONTROL ..................................................................................... 10
Optimum Comfort and Energy Savings……………………………………………………………………………….. 11
OPERATING YOUR THERMOSTAT ................................................................................................................. 13
Setting System and Fan Keys ............................................................................................................................ 13
Setting the System Key .................................................................................................................................. 14
Setting the Fan Key ........................................................................................................................................ 14
Setting Temporary Temperatures ....................................................................................................................... 15
Changing Temperature to Temporary Setting Until Next Schedule Period .................................................... 15
Changing and Holding Temperature Setting Indefinitely ................................................................................ 17
Changing Temperature Setting Until a Designated Day and Period (Vacation Hold) ..................................... 18
Using the (Information) Key ......................................................................................................................... 21
Displaying Outdoor Temperature .................................................................................................................... 21

469-1332—3
Contents (Cont)
Displaying Current Settings ............................................................................................................................ 22
Filter Indicator .................................................................................................................................................... 23
Setting or Resetting Filter Indicator ................................................................................................................ 23
LED Indicators ................................................................................................................................................... 25
Remote Override Temperature Indicator ............................................................................................................ 25
SETTING THE CLOCK...................................................................................................................................... 26
Set Current Day and Time ................................................................................................................................. 26
Daylight Saving Time ......................................................................................................................................... 28
PROGRAMMING YOUR THERMOSTAT .......................................................................................................... 29
7-Day Program and Operation ........................................................................................................................... 29
7-Day Preprogrammed Schedule ................................................................................................................... 30
Customizing Your Own 7-Day Schedule ........................................................................................................ 31
Programming the First Day ............................................................................................................................ 32
Copying a Day ................................................................................................................................................ 37
Clearing a Program Period ............................................................................................................................. 40
TROUBLESHOOTING....................................................................................................................................... 42
WARRANTY ...................................................................................................................................................... 45
CUSTOMER ASSISTANCE ............................................................................................................................... 47

569-1332—3
USING THIS GUIDE
The T8635L is a multi-functional thermostat. This means it can be used in several different ways such as single
or multi-zone applications, conventional furnaces or heat pump equipment.
The following symbols will help you identify the features that apply to your system:
– Triple layer of thermostats with the word, zoning, below. These features are available when more
than one thermostat is connected and used with the optional W8703 Damper Interface Module.
– Compressor with the word, heat pump, below. These features are available when used with a heat
pump with auxiliary heat.
–Tip symbol. Look for helpful tips throughout the guide when you see this symbol.
80
90
70
60
90
80
70
60
ZONING
HEAT PUMP

669-1332—3
FEATURES
•Adaptive Intelligent Recovery™ Control for comfort
and energy savings.
•Customize the program schedule—program your
own schedule to fit your needs.
•Temporary schedule override—set the thermostat
higher or lower for the current program schedule.
•Permanent schedule override—set the thermostat
higher or lower indefinitely.
•Vacation mode (1 to 255 days) for added comfort
and energy savings. Set the temperature higher or
lower for energy savings while on vacation. At the
same time, set the comfort level you want when
you return.
• Set the filter indicator (0, 15, 30, 60, 90, or
120 days) to remind you to change the filter.
•Information at the press of a button—use the
(information) key to see the outdoor tempera-
ture (C7089B Outdoor Temperature Sensor
optional accessory), the current setpoints, or
the filter status.
•No batteries needed—your thermostat retains the
schedule for the life of the product. You never have
to reprogram the schedule even after a power
outage. (You may need to reset the day and time
after an extended power outage.)
• Daylight Time key for quick time changes between
Daylight and Standard time.
•Backlit display for improved readability—set the
backlight feature for backlighting on demand
(press any key to activate) or continual backlight-
ing. Ask your installer to program this feature.
• Optional outdoor temperature display—ask your
installer to install an outdoor temperature sensor to
activate this feature.

769-1332—3
KEYBOARD AND DISPLAY DESCRIPTION
Keyboard
The keyboard is located behind the thermostat cover. Three frequently used keys, increase ▲or decrease ▼
and , are located next to the display. See Fig. 1.
Display
The thermostat displays important information such as day, time, schedule period, temperature, filter information,
system and fan operation. See Fig. 2.

869-1332—3
Fig. 1. Thermostat keyboard description.
M17459
Time Set Program
Run
Program
Hold Temp
Set Current
Day/Time
Day Heat/Cool
Settings
Wake
Fan
System
Copy
Daylight
Time
Leave Return Sleep
INCREASE
RAISES TEMPERATURE SETTING
DECREASE
LOWERS TEMPERATURE SETTING
INFORMATION
DISPLAYS CURRENT HEAT/COOL
TEMPERATURE SETTING
PROGRAM SCHEDULING
WAKE LEAVE RETURN SLEEP
ENTERS PROGRAMMING MODE
FAN
SELECTS AUTO/ON
SYSTEM
SELECTS HEAT/OFF/COOL (AUTO)
DIGITAL
DISPLAY
SET CURRENT
DAY/TIME
SETS CURRENT
DAY AND TIME
RUN PROGRAM
RETURNS THERMOSTAT TO
NORMALOPERATING MODE
HEAT/COOL SETTINGS
SWITCHES BETWEEN HEAT SETPOINTS AND
COOL SETPOINTS WHILE PROGRAMMING
TIME / TIME
SETS TIME
FORWARD OR BACK
HOLD TEMP
SETS A HOLDTEMPERATURE
SETTING AND ACTIVATES
VACATION HOLD FEATURE
DAYLIGHT TIME
SELECTS STANDARD TIME
OR DAYLIGHT SAVING TIME
COPY
COPIES SETTINGS FROM ONE DAY TO
ANOTHER DAY FOR QUICKPROGRAMMING
Filter
FILTER
SELECTS FILTER TIMER REMINDER
PERIOD (0, 15, 30, 60, 90, 120 DAYS)
DAY
SETS DAY OF THE WEEK
WAKE
SET WAKE TIMES
AND
TEMPERATURES
LEAVE
SET LEAVE TIMES
AND
TEMPERATURES
RETURN
SET RETURN TIMES
AND
TEMPERATURES
SLEEP
SET SLEEP TIMES
AND
TEMPERATURES

969-1332—3
Fig. 2. Example of thermostat display.
Auto
System
Fan
Off
Auto
Wake
Mon Room
AM
Recovery
Hold for
Filter Days
On
DST
Cool
TueWedThuFriSatSun
Leave Return Sleep
Set Program Set Day/Time Wait Temporary Setting
Em Heat
M17756
DISPLAYS
EITHER CURRENT
TIME OF DAY OR
PROGRAM TIMES
SHOWS
THERMOSTAT
IS IN THE
SET CURRENT
DAY/TIME MODE
SHOWS
TEMPERATURE
SETTING CHANGED
FOR THIS
PROGRAM
PERIOD
SHOWS TEMPERATURE
DISPLAYED IS THE CURRENT
SET TEMPERATURE
SHOWS
TEMPERATURE
DISPLAYED IS THE
CURRENT ROOM
TEMPERATURE
SHOWS FILTER TIMER
EXPIRED (TIME TO
REPLACE FILTER)
DISPLAYS EITHER ROOM
OR SET TEMPERATURE
SHOWS CURRENT FAN
KEY POSITION ON/AUTO
SHOWS THERMOSTAT IS
CALLING FOR THE FAN
SHOWS SMART
RESPONSE IS OFF
AND CONVENTIONAL
RECOVERY IS ON
SHOWS THERMOSTAT IS
PROCESSING INFORMATION
AND WAITING TO CALL FOR
HEAT OR COOL
SHOWS SMART
RESPONSE IS CHANGING
THE TEMPERATURE
TO MEET THE
CURRENT PROGRAM
SHOWS THAT THERMOSTAT
IS CALLING FOR
HEAT OR COOL
SHOWS CURRENT
SYSTEM KEY POSITION
HEAT/OFF/COOL
SHOWS CURRENT
PROGRAM PERIOD
OR PERIOD BEING
PROGRAMMED
SHOWS CURRENT
DAY OR DAYS BEING
PROGRAMMED
SHOWS WHEN
THERMOSTAT
IS IN THE
PROGRAMMING
MODE
SHOWS VACATION
HOLD DURATION
SHOWS SYSTEM ON
DAYLIGHT SAVING TIME
SHOWS THERMOSTAT
TEMPERATURE IS
BEING SET REMOTELY

10 69-1332—3
ADAPTIVE INTELLIGENT
RECOVERY™ CONTROL
Your new thermostat is so smart, it’s almost human.
You perceive temperature from a variety of sources,
not only from the air in the room, but also from your
surrounding walls, windows and furnishings. Humans
feel differences in temperature as slight as two
degrees Fahrenheit. Common household thermo-
meters and standard thermostats sense only air temp-
erature, which may not reflect how hot or cold the
room actually feels to you. Your new thermostat reads
both the temperature of the wall and in the air, and
responds to temperature changes as little as one
degree Fahrenheit, so room temperature is more
likely to feel right to you and your family.
The thermostat acts like a computer. When calculat-
ing the time to turn on your heating or cooling system,
it considers air temperature, wall temperature, and the
time you want to reach the comfort temperature. After
considering these three things, Adaptive Intelligent
Recovery™ control gradually changes the tempera-
ture from the energy savings setting to the comfort
setting (for example, from a heating temperature of
62°at night to 70°in the morning).
The system runs continuously until the comfort
temperature you choose is reached without over-
shooting the setting. This saves energy. How do you
know when the system is in recovery? The thermostat
displays “Recovery” whenever the thermostat
activates Adaptive Intelligent Recovery™ control. See
Fig. 3. So, “Recovery” displays during the recovery
time from Sleep to Wake and from Leave to Return.
Fig. 3. Example of “Recovery” indication.
M14561
Mon
Sleep
Room
System
Fan
Em Heat
Auto
AM
Heat
Recovery

11 69-1332—3
After installation or new schedule programming, your
thermostat learns from experience. Each day it
checks how closely it hit the recovery target (for
example, 70°at 6:00 AM) and adjusts the next day’s
recovery start time accordingly. After four to eight
days, the thermostat has adjusted to local weather,
your lifestyle, the construction of your home, and your
heating and cooling system.
Optimum Comfort and Energy Savings
In Fig. 4, Adaptive Intelligent Recovery™ control
starts to recover at 5:00 AM and reaches the comfort
temperature of 68°at 6:30 AM. Recovery time varies
with the starting temperature and the comfort temp-
erature you choose.

12 69-1332—3
At 4:00 AM
Recovery Begins
At 5:00 AM
Recovery
Continues
At 6:00 AM
Recovery
Continues
At 7:00 AM System
Operating in Comfort Mode
ENERGY
SAVINGS
PERIOD
RECOVERY FROM ENERGY SAVINGS COMFORT
PERIOD
TIME
TEMPERATURE
THE THERMOSTAT USES THE SAME SCHEME TO RETURN GRADUALLY TO LOWER COMFORT TEMPERATURE DURING THE COOLING SEASON.
M17758
Mon
Sleep
Room
System
Fan
Heat
Auto
AM
Recovery
Mon
Sleep
Room
System
Fan
Heat
Auto
AM
Recovery
Mon
Sleep
Room
System
Fan
Heat
Auto
AM
Recovery
Mon
Wake
Room
System
Fan
Heat
Auto
AM
IF In Recovery IS DISPLAYED, PRESS TO SEE THE COMFORT SETPOINT.
1
1
Fig. 4. Explanation of Adaptive Intelligent Recovery™ control.

13 69-1332—3
OPERATING YOUR THERMOSTAT
Your new thermostat saves energy and keeps you
comfortable at the same time. By now you may be
wondering how to program your thermostat and how
to use some more time and energy-saving features.
First, let’s look at features you’ll be using often, like
setting the System and Fan keys, how to override the
current programming mode or to hold the thermostat
at a specific temperature while you go on vacation.
You can even program the thermostat to return to
your regular programming schedule on your last day
of vacation so you are comfortable when you return
and yet save energy while you are away.
Setting System and Fan Keys
Use the System and Fan keys to change the system
and fan settings. The fan settings can be set for each
schedule period individually. The system selection is
for all the schedule periods.
CAUTION
Equipment Damage Hazard.
Can cause permanent damage to the
compressor or other equipment.
To avoid possible compressor damage, allow
the compressor to remain off for five minutes
before restarting.
To avoid possible equipment damage, do not
operate cooling when the outside temperature
is below 50°F (10°C). See equipment manu-
facturer instructions.

14 69-1332—3
Setting the System Key
Press the System key until the desired
system (Heat, Off, Cool, or Auto) displays.
Heat: The thermostat controls the heating.
Off: Both the heating and cooling are off.
Cool: The thermostat controls the cooling.
Auto: The thermostat automatically changes
between heating and cooling operation,
depending on the indoor temperature.
Auto is not available when used with zoning.
Changing any thermostat system
setting on any thermostat automatically
changes the system setting in all zones. For example,
changing the zone 1 thermostat from Heat to Cool
causes all thermostats to change from Heat to Cool.
System
Em.Ht: Emergency heat is controlled as
stage 1 heat. Cooling system is off.
Compressor is de-energized. (Available
only with multistage heat pump.)
Setting the Fan Key
Press Fan key until the desired mode
(On or Auto) displays:
On: Fan operates continuously.
Auto: Fan operates only when heating
or cooling.
displays when the thermostat is calling
for the fan in this zone. A flashing
indicates that the thermostat is waiting
until another zone has completed its
call for heat or cool before initiating the fan call for
this zone.
Fan
ZONING
HEAT PUMP
ZONING

15 69-1332—3
Setting Temporary Temperatures
You can override the current schedule period to temporarily change the temperature setting until the next schedule
period, or you can change and hold the temperature setting indefinitely. You can also change the temperature setting
until a designated day and period (for example, while you are on vacation).
Changing Temperature to Temporary Setting Until Next Schedule Period
Press increase ▲or decrease ▼until the desired temperature
setpoint displays.
The temporary temperature setting you select displays for
approximately three seconds. The display reads “Temporary”
until the next period begins or when you cancel the temporary
temperature setting.
While selecting a temporary setting, only the setpoint displays.
M14563
Temporary Setting

16 69-1332—3
Press the Run Program key to cancel the temporary
temperature setting before the designated time.
Run
Program
M14564
Mon
System
Fan
Heat
Auto
AM
Heat
Temporary
After selecting a temporary setting, the display reads
“Temporary” until canceled. Example display shows
temporary heat setting of 70°at 6:00 AM.
If ▲or ▼appears under the temperature display, it means that both the heating and cooling
setpoints are being adjusted. Tapping the increase ▲or decrease ▼key changes both the heat
and cool setpoints by one degree. Press key after the desired setpoint is reached to verify
the setpoints.
80
90
70
60
90
80
70
60

17 69-1332—3
M14565
System
Fan
Heat
Auto
Heat
Setting
Changing and Holding Temperature Setting Indefinitely
1. Press Hold Temp key once.
2. Press increase ▲or decrease ▼to change the tempera-
ture setpoint, if desired.
NOTE: The display changes from the setpoint to the
room temperature after approximately three
seconds.
Press Run Program key to cancel hold.
Press Hold Temp key once to display the thermostat in Hold
mode. Example display shows temporary heat setting of 60°.
Hold Temp
Run
Program

18 69-1332—3
Changing Temperature Setting Until a Designated Day and Period (Vacation Hold)
Hold Temp
Press the Time or Time key to select the number of vacation
days. Example display shows 18 vacation days.
TIME
M14833
Wake
System
Fan
Heat
Auto
Hold for
Heat
Days
Setting
ZONING
M14834
Wake
System
Fan
Heat
Auto
Hold for
Heat
Days
Setting
When setting Vacation Hold at any
thermostat, all thermostats automati-
cally change to Vacation Hold except if
a thermostat is already set to Hold.
1. Press Hold Temp key twice.
IMPORTANT
To cancel the Vacation Hold before the
designated time, press Run Program key.
2. Press Time or Time until the desired
number of days (1 to 255
days) displays.
Press Hold Temp key twice to display the thermostat in Vacation
mode. Example display shows temporary heat setting of 60°.

19 69-1332—3
Press Wake, Leave, Return or Sleep key to select the
period the Hold ends.
M14571
System
Fan
Heat
Auto
Hold for
Heat
Days
Setting
Return
4. Press increase ▲or decrease ▼to adjust the tempera-
ture setting, if desired.
NOTE: Only the heating temperature is used when
the System is set to Heat. Similarly, only the
cooling temperature is used when the System
is set to Cool. The thermostat uses both the
heating and cooling temperatures when the
System is set to Auto. Press increase ▲or decrease ▼key to select
a new Hold temperature. Example display
shows temporary heat setting of 55°.
M14572
System
Fan
Heat
Auto
Hold for
Heat
Days
Setting
Return
In this example, the Hold ends after the 18th
day at the beginning of the Return period.
Leave Return SleepWake

20 69-1332—3
Auto changeover is not an available feature.
5. Press Heat/Cool Settings key to change between heat and cool settings.
6. Press increase ▲or decrease ▼to adjust the temperature setting, if desired (for example, if cool is set at
84°, cooling equipment operates when the room temperature is above 84°F).
To cancel the Vacation Hold before the designated time, press Run Program key at each thermostat.
Pressed the wrong key?
Want to start over?
Don’t worry!
You can always press
to return display to normal.
Heat/Cool
Settings
Run
Program
ZONING
ZONING