Honeywell Chronotherm 3 User Manual

							15
To temporarily raise or lower the
temperature for the current period
only.
If you change your mind.WARMER
COOLER
TUE
LEAVEPMSET
PTRUN
PROGRAM
AHEAD
BACK
RUN
PROGRAM
WARMER
COOLER
SLEEP
WAKELEAVE
RETURN
DAY
Press and hold until the desired
temperature is reached. The display
will flash TEMPORARY until the next
programmed time period starts.
Press and release to cancel any of
the temporary settings.
Press and release the desired period
key.
Press and hold until the desired day
schedule shows on the display. PERMANENTLY CHANGING THE
PROGRAM
If your schedule changes or you
want a different temperature, you
can update any setting without
affecting the rest of the program.
Press and hold the Time or Tem-
perature keys until the display shows
the desired new program.
Press and release to return to
normal operation.
OPERATING THE THERMOSTAT
MANUALLY
This feature lets you set one
temperature that the thermostat will
hold continuously. Your preset
schedule will resume when you
push the RUN PROGRAM key.Press and release.
Press and hold to change the
temperature setting. After a few
seconds, the display will show the
current temperature.
Press and release to check the
temperature setting.
Press and release to cancel hold.
ON HEATSET
PT
ON HEATSET
PT
PRESENT
SETTING
RUN
PROGRAM
HOLD
TEMP
WARMER
COOLER
ON HEATSET
PT
OPERATING YOUR THERMOSTAT
TUE
LEAVEPM
16 
						

							17
18
OPERATING YOUR THERMOSTAT
CANCELING PROGRAM
SETTINGS
The thermostat requires time and
temperature settings in the WAKE
period, but any of the other periods
can be canceled. Weekday,
Saturday and Sunday settings are
canceled separately.Press and hold the desired period
key until the time and temperature
clear from the display (about 3
seconds).
Press and release to return to
normal operation.SLEEP
LEAVE
RETURN
RUN
PROGRAM
MON TUE WED THU FRI ON HEAT
LEAVE
MON
RETURNPM
CHECKING THE PROGRAM
TIMES AND TEMPERATURES
You can check all the stored
settings without affecting the
permanent program.
SLEEP
WAKEPress and release the desired
period key. The start time and
temperature setting will appear on
the display.
Press and release to display the
next daily time and temperature for
that period.
Press and release to return to
normal operation.
LEAVE
RETURN
MON TUE WED THU FRI ON HEAT
SLEEPPMSET
PT
SAT ON HEAT
SLEEPPMSET
PT
RUN
PROGRAM
MON
RETURNPM
DAY 
						

							19
20
CHECKING THE CURRENT
TEMPERATURE SETTING
Press a single key to compare
current room temperature to the
setting at any time.PRESENT
SETTINGPress and release. The display will
show the current temperature setting
for several seconds, then revert to
the room temperature.
ON HEATSET
PT
ACCSING EXTERNAL SYSTE OPERATING YOUR THERMOSTAT
EXTERNAL ACCESS AND
CONTROL OF THERMOSTAT
The T8631 Communicating
Chronotherm III Thermostat can
be connected to a Honeywell
TotalHome system for external
access and control.
A TotalHome system allows you
to change thermostat settings
from the systems user interface
panels. depending on the system
chosen, you can also use a
touchtone phone to adjust your
setting. Whenever the thermostat
is controlling to TotalHOme
system setting, a s
s appears
under the room temperature
display.
You can easily make temporary
temperature setting changes by
pushing the 
WARMER orCOOLER key on the T8631. The
temporary override setting lastsuntil the next period starts. To
permanently change the tempera-
ture set point, push the desired
period key, then the 
WARMER orCOOLER key. Use the RUN
PROGRAM key to change from
external system control to thermo-
stat control of program times and
temperatures until a new command
is received from the TotalHome
system.
The T8631 Thermostat can
communicate on an HBus network
over four-wire conductor cables.
This cable connects to the H1, H2,
H3 and H4 terminals on the
thermostat.
HBus is a Honeywell proprietary
communications protocol.
For assistance, call Consumer
Services, 1-800-468-1502, Monday-
Friday, 7:30 a.m. to 5:00 p.m.,
Central time.
MON
WAKE
AMSET
PT 
						

							22
REMOVING THE THERMOSTAT
1 Loosen the two captive screws at
the bottom corners of the case.2 Pull out the thermostat from the
bottom.3 Lift the thermostat up and off the
base.
AUX. HEAT
HEAT
AUTOCOOLOFFO
N
A
U
T
OF
A
N
M5066
SYSTEM
E
M
.
 
H
T
.H
E
A
TO
F
FONAUTOFAN
M5013
C
O
O
LEM. HT.AUX. HEAT
SYSTEMPMRETURN MON
HEAT ONSYSTEM
M5062
R
U
N
P
R
O
G
R
A
M
T
I
M
ET
E
M
P
E
R
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P
R
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T
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X
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P
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O
 
L
A
S
T
P
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R
I
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D S
E
T
P
R
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S
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N
T
D
A
Y
/
T
I
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H
O
L
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T
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M
P
D
A
Y
S
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T
H
E
A
T
/
C
O
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LS
L
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PL
E
A
V
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A
H
E
A
DW
A
R
M
E
R
R
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T
U
R
NB
A
C
KC
O
O
L
E
R W
A
K
EP
E
R
I
O
D
3 Tighten the captive screws.
M5014HEATAUTOCOOLOFFO
NA
U
T
OF
A
NE
M
.
 
H
T
.
A
U
X
.
 
H
E
A
T
PMRETURNMON
HEAT ONSYSTEM
A
U
T
O
M5063
REPLACING THE THERMOSTAT
1 Hang the thermostat on the tabs
at the top of the subbase.2 Swing down and press bottom
edge until thermostat snaps in
place.
21
MAINTAINING YOUR THERMOSTAT
P
MR
E
T
U
R
N M
O
N
H
E
A
T
 
O
NSYSTEM
M5075
R
U
N
P
R
O
G
R
A
M
T
IM
ET
E
M
P
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R
A
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P
R
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S
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N
T
S
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T
T
IN
G
S
K
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N
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X
T
P
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R
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D
C
H
A
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T
O
 
L
A
S
T
P
E
R
IO
D S
E
T
P
R
E
S
E
N
T
D
A
Y
/
T
I
M
E
H
O
L
D
T
E
M
P
D
A
Y
S
E
T
H
E
A
T
/
C
O
O
LS
L
E
E
PL
E
A
V
E
A
H
E
A
DW
A
R
M
E
R
R
E
T
U
R
NB
A
C
KC
O
O
L
E
R W
A
K
EP
E
R
I
O
D 
						

							23
24
MAINTAINING YOUR THERMOSTAT
REPLACING THE BATTERIES
Your thermostat uses three AAA alkaline batteries. The
display will flash REPL BAT when the batteries get low.
You wonÕt have to reprogram the thermostat if you
insert the new batteries within 20-30 seconds of taking
out the old ones.
To replace:
nSet the system switch to OFF.
nRemove the thermostat from the wall. See page 21.
nLift the batteries out of the holder.
nInsert the new batteries, making sure the positive (+)
terminals all face toward the right.
nReplace the thermostat on the wall. See page 22.
nReprogram, if necessary.
M5065
POWER OUTAGES
Backup batteries will hold the programming and keep
on the display during most power outages. Once the
power is restored, the system will resume normal
operation.If the display goes off when power is lost, either the
backup batteries need to be replaced or were not
installed. When power is restored, the display will flash
1:00 PM to remind you to reprogram. If the colon is not
flashing, there is no AC power or the thermostat is not
properly connected to the subbase. 
						

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26
ADAPTIVE INTELLIGENT RECOVERYª
M 168
ADAPTIVE INTELLIGENT
RECOVERYªÑBREAK-
THROUGH TECHNOLOGY
SENSES TEMPERATURE MORE
LIKE YOU DO
Your new thermostat is so smart,
itÕs almost human.n
Your body perceives temperature from a variety of sources, not only from
the air in the room, but also from your surroundingsÑwalls, windows and
furnishings.
n
Human beings feel differences in temperature as slight as two degrees
Fahrenheit.
n
Common household thermometers and standard thermostats sense only
air temperature, which may or may not reflect how hot or cold the room
actually 
feels to a human being.
n
Your new thermostat reads both the temperature of the wall and the airÑ
and responds to temperature changes as little as one degree Fahren-
heitÑso room temperature is more likely to 
feel right to you and your
family. 
						

							27
28
AM
PMSUN   MON   TUE   WED   THU   FRI   SAT    COOL    ON HEAT    ONWAKE   LEAVE   RETURN   SLEEP     TEMPORARY     UNOCCUIPIED
REPL
BATSET
PT
AM
PMSUN   MON   TUE   WED   THU   FRI   SAT    COOL    ON HEAT    ONWAKE   LEAVE   RETURN   SLEEP     TEMPORARY     UNOCCUIPIED
REPL
BATSET
PT
AM
PMSUN   MON   TUE   WED   THU   FRI   SAT    COOL    ON HEAT    ONWAKE   LEAVE   RETURN   SLEEP     TEMPORARY     UNOCCUIPIED
REPL
BATSET
PT
AM
PMSUN   MON   TUE   WED   THU   FRI   SAT    COOL    ON HEAT    ONWAKE   LEAVE   RETURN   SLEEP     TEMPORARY     UNOCCUIPIED
REPL
BATSET
PT
System Operating
in Energy Savings ModeRecovery BeginsRecovery ContinuesSystem Operating
in Comfort Mode
ENERGY
SAVINGS
PERIODRECOVERY FROM ENERGY SAVINGSCOMFORT
PERIOD
TIME
TEMPERATURE
THE THERMOSTAT USES THE SAME SCHEME TO RETURN  GRADUALLY
TO LOWER COMFORT TEMPERATURE DURING THE COOLING SEASON.M 171
THE OPTIMUM COMFORT AND
ENERGY SAVINGS SOLUTION
n
This thermostat is actually a small but powerful computer. When calculat-
ing the exact time to turn on your furnace or air conditioner, it considers
(1) air temperature, (2) temperature of the wall and (3) when you want
the comfort temperature established.
n
During the Adaptive Intelligent Recovery setting, the thermostat in-
creases the control temperature gradually and turns the equipment on
and off
 several times to save energy by avoiding overshooting the
comfort temperature. You can see the current control temperature
anytime during recovery by pressing the PRESENT SETTING key.
n
This smart control learns from experience. Each day it checks how
closely it hit the target and adjusts the recovery start time accordingly.
n
It typically takes four to eight days after installation for this thermostat to
adjust to the weather, your life style, home construction and heating/
cooling system. The thermostat calculates the LEAVE/RETURN recovery
separately from the SLEEP/WAKE recovery.
n
With the T8631A, you can choose whether you want to use Adaptive
Intelligent Recoveryª or conventional recovery. Use the Adaptive
Intelligent Recovery setting if you want to choose the exact time that the
room reaches your 
comfort temperature. Use conventional recovery if
you prefer to choose the exact time your furnace or air conditioner comes
on to start recovery.
ADAPTIVE INTELLIGENT RECOVERYª 
						

							SELECTING RECOVERY SETTING
29
30
Your T8631A Thermostat includes a screw on the back
marked 2A, allowing for the Adaptive Intelligent Recov-
eryª/Conventional Recovery choice.
Your thermostat was shipped from the factory with the
screw positioned for Adaptive Intelligent Recovery
setting. Your installer may have left the screw in this
position, or may have changed it to Conventional
Recovery. Before programming, you must know which
recovery method your thermostat has been set for.
¥ With the Adaptive Intelligent Recovery setting, the
dwelling will reach the comfort temperature at the
exact time you have programmed into the thermo-
stat.
¥ With Conventional Recovery, the programmed time
will be the time your furnace comes on to start
recovery; therefore, you should program the start
time to be earlier than the desired comfort time. It
may require some trial and error for you to arrive at
the best starting time, and the best starting time will
vary as the seasons change.
SYSTEM
GRAVITY
AIR/WATER
HOT
WATER
GAS/OIL
WARM AIR
ELECTRIC
WARM AIR1A
OUT
1 TURNOUT  
 1 TURN
OUT
 1 TURN
OUT 
1 TURN1B
ININ
(FACTORY SETTING)IN
IN
M3064
1A1B
2A2B
DISPLAY TEMPERATURE
2BoC
FoOUT IN
2B
2A
OUTIN
2A RECOVERY OPTION
ADAPTIVE
CONVENTIONALHEAT 
CYCLE RATE
To determine which type of recovery is
set into your T8631A Thermostat,
make sure your thermostat is mounted
and powered on the wall.
Press key. Check thermostat display.
¥ If the n
n shows in the lower right-
hand corner (see illustration), the
thermostat is set for Conventional
Recovery. If you would rather have
the Adaptive Intelligent Recovery
setting, remove thermostat from
wall, turn screw 2A (on back of
thermostat) clockwise   until it
bottoms. DO NOT OVERTIGHTEN.
¥ If the n
n does not show, the
thermostat is set for Adaptive
Intelligent Recoveryª. If you would
rather have Conventional Recov-
ery, remove thermostat from wall,
turn screw 2A (on back of thermo-
stat) out    1/2 to 1 turn.
MON
WAKE
AM
M5058
INDICATES 
THERMOSTAT IS SET FOR 
CONVENTIONAL RECOVERY
RUN
PROGRAM 
						

							HEAT PUMP WITH SUPPLEMENTAL HEAT
HEAT PUMPS ARE DIFFERENT (T8631R)
nHeat pump systems usually have a supplemental,
second stage heating system that operates only
when necessary
. The Honeywell Chronotherm III
Thermostat for heat pumps is designed to minimize
the more expensive second-stage operation,
indicated by the green AUX light on the switching
subbase.
n
With your Chronotherm III Thermostat, you will
notice that your compressor operates continuously
during the recovery period
. This may appear to
waste energy, but it is actually more efficient.
Multiple ON-OFF cycles are neither necessary to
achieve comfort, nor as efficient for heat pump
systems. By reducing the number of cycles, you
reduce the strain on your system and extend
equipment life.
AUXILIARY
HEATING
ELEMENT
OFF
OUTDOOR
AIR
INDOOR
AIR
HEAT
TRANSFERINDOORS OUTDOORSAUXILIARY
HEATING
ELEMENT
ON
OUTDOOR
AIR
INDOOR
AIR
HEAT
TRANSFERINDOORS OUTDOORS
MILD WEATHER SEVERE WEATHER
nIn mild weather, almost all of the demand for heat in
buildings can be met by the heat pump compressor.
This first stage process of moving heat indoors is
very economical. As the air becomes colder outside,
the first stage may be unable to deliver enough heat
to maintain the desired comfort level in the building.n
During high heat demand, the thermostat will call for
additional second stage power from the auxiliary
heat system
. This auxiliary heat is commonly
electric resistance heat and is two to three times
more expensive to operate than the compressor.
31
32
HEAT PUMPS ARE TWO SYSTEMS IN ONE 
						

							33
34
ANSWERING COMMON QUESTIONS ABOUT THE CHRONOTHERM III THERMOSTAT
3. Why does the T8631 follow a schedule not
programmed into the thermostat?
When the s 
s is displayed, the thermostat is control-
ling to the setting in your TotalHome system.
4. How many hours in advance of my WAKE time
should the furnace come on?
The time will vary, up to 24 minutes per degree
Fahrenheit difference between the energy saving
and comfort temperatures, depending on outside
temperature and performance during the past 24
hours. A microchip computer with Adaptive Intelligent
Recoveryª allows the thermostat to 
think for itself
and adjust the furnace or air conditioning recovery
time to reach your desired comfort temperature at
the programmed time. Whenever the temperature is
more than one degree hotter or colder than the
comfort temperature at the programmed time, the
system turns on earlier the next day. This approach
ensures the temperature wonÕt over- or under-shoot
the set point and allows the proper amount of time
for recovery.
5. What does the HOLD key do?
It bypasses 
all program settings and holds the
temperature at the present setting. To increase or
decrease the temperature while on HOLD, use the
WARMER-COOLER keys. Pressing the thermostatÕs
RUN PROGRAM key or entering a change at the
external system will return the device to programmed
operations.
6. How long does the HOLD key hold?
Forever! The HOLD key will hold the temperature
indefinitely. The only way to release it is to press the
RUN PROGRAM key or enter a change at the
TotalHome system.
7. How can the T8631A Thermostat save energy
when it comes on and off so many times early in
the morning hours?
Two ways. First, it 
saves energy (and money) by
setting back the temperature for blocks of time
during the day or night. Second, it conserves energyby recovering gradually to the desired temperature. 1. The temperature displayed on the Chronotherm III
Thermostat doesnÕt always match the room
temperature on another thermometer located
right next to it. Why?
The Chronotherm III Thermostat is a 
very accurate
instrument designed to sense both air temperature
and wall temperature, like your body does. It gives an
average reading over a period of time. Because it
adjusts itself, it will take a few days after installation
to adjust to your home.
2. A s
s triangle symbol is on the display sometimes.
What does it mean?
The T8631 Communicating Chronotherm III Thermo-
stat can be connected to a Honeywell TotalHome
system for external access and control. Whenever
the thermostat is controlling to TotalHome system
settings, a s
s appears under the room temperature
display.
This prevents 
overshooting your comfort set point
(and wasting energy) or under-shooting the comfort
set point (and forcing you to change the thermostat
setting, also wasting energy).
Honeywell experts have invested years of engineer-
ing and in-home testing to assure that this is the
most effective way to set back and save energy
while optimizing your comfort.
8. Sometimes my Chronotherm III Thermostat
doesnÕt allow the house temperature to drop to
my SLEEP setting before it starts bringing the
furnace on. Why?
Many factors affect your comfort and energy
savings. If those factors, such as weather, humidity,
etc. were 
always consistent, an unchanging program
would work just fine. But factors change. The whole
point of Adaptive Intelligent Recoveryª is to save
energy 
without sacrificing comfort. If necessary, the
Adaptive Intelligent Recoveryª will override your
temperature settings to assure accurate temperature
recovery with optimum comfort and energy savings
for the 
current conditions.