Honeywell T8624 User manual

Programmable Multistage Thermostat
OWNER’S GUIDE
Your new programmable thermostat is a precision instrument that’s quality-built to give you many years of satisfactory
service. It’s a “smart” thermostat that lets you save energy while still maintaining the standard of comfort you want in your
home.
This Owner's Guide will show you how to get the most benefit from your new thermostat.

Programmable Multistage Thermostat
OWNER’S GUIDE
Your new programmable thermostat is a precision instrument that’s quality-built to give you many years of satisfactory
service. It’s a “smart” thermostat that lets you save energy while still maintaining the standard of comfort you want in your
home.
This Owner's Guide will show you how to get the most benefit from your new thermostat.

Monitor thermostat operation, read current
time and room temperature at a glance.
Check status light to see if the
thermostat is on, even in the dark.
Set different
schedules for
weekdays,
Saturday, and
Sunday.
Choose manual or
automatic thermo-
stat operation.
Program up to four
different time
periods in each
schedule.
Set the tempera-
ture warmer or
cooler at the touch
of a key.
Bypass the stored
program for a
single period.
Choose system and
fan operating
modes with the
thermostat
switches (on
subbase).
Simple Four-Step Programming
Of course, you can use the schedule preprogrammed into your new thermostat (see
Glossary, page 35). But it’s an easy matter to program the thermostat to fit your
lifestyle.
1Set the current time and day. See page 6.
2Set the program schedule and heating temperatures. See page 7.
3Set the cooling temperatures. See page 14.
4Set the system and fan switches. See page 20.
Features

Adaptive Intelligent Recovery™ ...........................1-4
Programming Your Thermostat ..........................5-22
Set the current day and time .................................. 6
Set the program schedule and
heating temperatures ......................................... 7
Set the cooling temperatures................................ 14
Set the system and fan switches on the subbase 20
Operating Your Thermostat...............................23-30
Temporarily changing the program ...................... 23
Permanently changing the program ..................... 25
Manually operating the thermostat ....................... 26
Canceling the program settings ............................ 27
Checking the program times and temperatures ... 28
Checking the current temperature setting ............ 29
Maintaining Your Thermostat............................31-34
Removing the thermostat ..................................... 31
Replacing the thermostat...................................... 32
Replacing the batteries ......................................... 33
Power outages ...................................................... 34
Glossary ..............................................................35-36
Your Personal Program .....................................37-38
Troubleshooting Guide ......................................39-40
Chronotherm®III Thermostat Questions .........41-42
Quick Reference to the Keys.............................43-44
Index.....................................................................45-46
Limited One-Year Warranty .................................... 47
TABLE OF CONTENTS
i

CONDITIONED
AIR CONDITIONED
AIR
RETURN AIR
REGISTER SUPPLY AIR
REGISTER
STALE AIR
EXHAUST
FRESH AIR
INTAKE
HONEYWELL
HOME
VENTILATION
SYSTEM
HONEYWELL
ELECTRONIC AIR CLEANER
HONEYWELL
WATER FILTER
OPTIMAL
EFFICIENCY
FORCED AIR
FURNACE
FRESH
AIR TO
HOME
HUMIDIFIER
OPTIMAL
EFFICIENCY AIR
CONDITIONER
OR HEAT PUMP
THE
CHRONOTHERM lll
THERMOSTAT IS ONE
PART OF A PERFECT CLIMATE
SYSTEM, AN INDOOR ENVIRONMENT THAT
PROVIDES TOTAL INDOOR COMFORT. IT MAKES
YOU FEEL BETTER; ALLOWS YOU TO LIVE AND WORK
IN A MORE COMFORTABLE ENVIRONMENT; ACHIEVES
MAXIMUM ENERGY SAVINGS AND MAINTAINS PRECISE
CONTROL OVER INDOOR TEMPERATURE AND HUMIDITY.
COLD AIR
RETURN STALE
AIR FROM
BATHS
®
®
M3755
How it works...
HONEYWELL
DEHUMIDISTAT
HOME
VENTILATION
SYSTEM
FRESH AIR
CONTROL
HONEYWELL
ELECTRONIC
AIR CLEANER
PERFORMANCE
STATUS
INDICATOR
HONEYWELL
RESIDENTIAL
SECURITY
SYSTEM
HONEYWELL
CHRONOTHERM lll
PROGRAMMABLE
THERMOSTAT
®
®
CONSIDER THE COMPLETE
PACKAGE FOR A PERFECT
CLIMATE® SYSTEM IN
YOUR HOME
ii

Honeywell manufactures the following components of a Perfect Climate
System:
1. Honeywell Chronotherm®Programmable Thermostats
2. Honeywell F50, the air cleaners of choice
3. Honeywell Dehumidistats
4. Honeywell Home Ventilation Systems
5. Honeywell F76 Water Filter
6. Honeywell Home Security Systems
iii

ADAPTIVE INTELLIGENT
RECOVERY™—BREAKTHROUGH
TECHNOLOGY SENSES
TEMPERATURE MORE LIKE YOU DO
M168
1
ADAPTIVE INTELLIGENT RECOVERY™

The Chronotherm®III Thermostat is
so smart, it’s almost human.
■ Your body perceives temperature from a variety of sources, not only from
the air in the room, but also from your surroundings—walls, windows and
furnishings.
■
Human beings feel differences in temperature as slight as two degrees
Fahrenheit.
■ 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.
■
The Chronotherm III Thermostat reads the temperature of the wall as well
as 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.
2
ADAPTIVE INTELLIGENT
RECOVERY™

ADAPTIVE INTELLIGENT RECOVERY™
3
AM
PM
SUN MON TUE WED THU FRI SAT COOL ON HEAT ON
WAKE LEAVE RETURN SLEEP TEMPORARY UNOCCUIPIED
REPL
BAT
SET
PT
AM
PM
SUN MON TUE WED THU FRI SAT COOL ON HEAT ON
WAKE LEAVE RETURN SLEEP TEMPORARY UNOCCUIPIED
REPL
BAT
SET
PT
AM
PM
SUN MON TUE WED THU FRI SAT COOL ON HEAT ON
WAKE LEAVE RETURN SLEEP TEMPORARY UNOCCUIPIED
REPL
BAT
SET
PT
AM
PM
SUN MON TUE WED THU FRI SAT COOL ON HEAT ON
WAKE LEAVE RETURN SLEEP TEMPORARY UNOCCUIPIED
REPL
BAT
SET
PT
System Operating
in Energy Savings Mode
Recovery Begins Recovery Continues
System Operating
in Comfort Mode
ENERGY
SAVINGS
PERIOD RECOVERY FROM ENERGY SAVINGS COMFORT
PERIOD
TIME
HEATING TEMPERATURE
M3780
■ The Chronotherm III Thermostat is actually a small but powerful
computer . When calculating the exact time to turn on your furnace or
air conditioner, it considers: (1) air temperature, (2) the temperature of
the wall and (3) when you want the comfort temperature established.
THE CHRONOTHERM®III
THERMOSTAT—THE OPTIMUM
COMFORT AND ENERGY
SAVINGS SOLUTION

■ During Adaptive Intelligent Recovery™, the thermostat increases 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.
■
This “smart”control learns from experience. Each day it checks how
closely it hit the target and adjusts the recovery start time accordingly.
It typically takes four to eight days after installation for the Chronotherm III
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.
PROGRAMMING YOUR THERMO-
STAT
4

5
PROGRAMMING YOUR THERMOSTAT
IMPORTANT With Adaptive Intelligent Recovery™, program the times for when you want
your home comfortable. The thermostat will decide how early to begin the
temperature changes.
NOTE: Some models will show
32°F instead of the current
temperature, indicating the
thermostat is operating on
backup batteries until the
thermostat is mounted on the
wallplate and the system is
powered.

PROGRAMMING YOUR
THERMOSTAT 6
Press and release. The display
shows 1:00 PM MON.
Press and hold until the current
day appears in the display.
Press and hold until the current
time appears in the display. Be
sure AM or PM appears as
desired.
You have programmed the
current day and time. Go on to
Step 2.
STEP 1
SET THE CURRENT DAY
AND TIME
You can program this thermostat either
on the wall or in your hand. SEE PAGE
31 TO FIND OUT HOW TO REMOVE
THE THERMOSTAT FROM THE
WALL.
Always press the keys with your
fingertip or similar blunt tool. Sharp
instruments like a pen or pencil point
can damage the keyboard.
NOTE: Check the glossary, page 35, for
definitions of unfamiliar words.
MON
PM
M5015
SET
PRESENT
DAY/TIME
DAY
AHEAD
BACK
TUE
M5016
PM
TUE
PM
M5017

7
PROGRAMMING YOUR THERMOSTAT
STEP 2
SET THE PROGRAM SCHEDULE
AND HEATING TEMPERATURES
Before You Begin…
The schedule form on page 37 provides
an opportunity to plan your schedule.
Now…
Start by programming the WAKE time
and temperature for weekdays.
The thermostat requires a program for
WAKE. You can program LEAVE,
RETURN and SLEEP or not, as you
please.
Press and release. Note that the display
shows WAKE and the
preprogrammed time and
temperature.
If the display reads COOL, press
and release to switch to HEAT.
If display reads SAT or SUN,
press and hold until MON TUE
WED THU FRI appears.
Press and hold until the display
shows the desired starting time.
WAKE
SET
HEAT/COOL
DAY
AHEAD
BACK
MON TUE WED THU FRI ON HEAT
WAKE
AM
SET
PT
M5018
MON TUE WED THU FRI ON HEAT
WAKE
AM
SET
PT
M5018
MON TUE WED THU FRI ON HEAT
WAKE
AM
SET
PT
M5018
MON TUE WED THU FRI ON HEAT
WAKE
AM
SET
PT
M5019

8
Press and hold until the
display shows the desired
temperature.
If the display starts to blink
while you are holding down
TEMPERATURE WARMER
or COOLER, you have
reached the setting limit. If
your thermostat can switch
automatically between
heating and cooling, the
heating temperature must be
at least three degrees below
the air conditioning tempera-
ture. For example, if the
cooling setting is
75°F, the maximum heating
setting is 72°F.
WARMER
COOLER
MON TUE WED THU FRI ON HEAT
WAKE
AM
SET
PT
M5020

9
PROGRAMMING YOUR THERMOSTAT
Program the LEAVE time and tempera-
ture, if desired.
NOTE: You can cancel the LEAVE,
RETURN or SLEEP program by
holding down the period key until the
time and temperature disappear
from the display.
Press and release. The display
shows LEAVE, but no time or
temperature.
Press and hold until the display
shows the desired starting time.
Press and hold until the display
shows the desired temperature.
LEAVE
MON TUE WED THU FRI ON HEAT
LEAVE
SET
PT
M5021
AHEAD
BACK
MON TUE WED THU FRI ON HEAT
LEAVE
AM
SET
PT
M5022
MON TUE WED THU FRI ON HEAT
LEAVE
AM
SET
PT
M5023
WARMER
COOLER

10
Program the RETURN time and
temperature, if desired. Press and release. The display shows RETURN, but no time or
temperature.
Press and hold until the display
shows the desired starting time.
Press and hold until the display
shows the desired temperature.
RETURN
AHEAD
BACK
WARMER
COOLER
MON TUE WED THU FRI ON HEAT
RETURN
SET
PT
M5024
MON TUE WED THU FRI ON HEAT
RETURN
PM
SET
PT
M5025
MON TUE WED THU FRI ON HEAT
RETURN
PM
SET
PT
M5026

PROGRAMMING YOUR THERMOSTAT
Program the SLEEP time and tempera-
ture, if desired. Press and release. The display shows SLEEP and the
preprogrammed time and tempera-
ture.
Press and hold until the display
shows the desired starting time.
Press and hold until the display
shows the desired temperature.
SLEEP
MON TUE WED THU FRI ON HEAT
SLEEP
PM
SET
PT
M5027
AHEAD
BACK
WARMER
COOLER
MON TUE WED THU FRI ON HEAT
SLEEP
PM
SET
PT
M5060
MON TUE WED THU FRI ON HEAT
SLEEP
PM
SET
PT
M5028
11

Set the SATURDAY schedule. Use
the same procedure as for weekdays. Press and release until SAT appears on the display.
Press WAKE, LEAVE, RETURN
or SLEEP to select the time
period.
Use the AHEAD/BACK keys to
set the time and the WARMER/
COOLER keys to set the
temperature.
DAY
SAT ON HEAT
SLEEP
PM
SET
PT
M5029
SLEEP
WAKE LEAVE
RETURN
WARMER
COOLER
AHEAD
BACK
12

PROGRAMMING YOUR THERMOSTAT
Set the SUNDAY schedule. Use the
same procedure as for weekdays. Press and hold until SUN appears on the display.
Press WAKE, LEAVE, RETURN
or SLEEP to select the time
period.
Use the AHEAD/BACK keys to
set the time and the WARMER/
COOLER keys to set the
temperature.
You have completed setting the
program schedule and heating
temperatures. To set air condi-
tioning, go to Step 3.
DAY
SUN ON HEAT
SLEEP
PM
SET
PT
M5030
LEAVE
RETURNSLEEP
WAKE
AHEAD
BACK
WARMER
COOLER
If you do not want to program cooling temperatures,
skip Step 3 and press the RUN PROGRAM key. 13

STEP 3
SET THE COOLING
TEMPERATURES
The program times are the same for
both heating and cooling. Only the
cooling temperatures need to be
programmed if you have already
programmed for heating. To set times
as you program the cooling tempera-
tures, use the TIME AHEAD and BACK
keys as described in Step 2. But if you
change times for cooling, you are also
changing them for heating!
First program the WAKE temperature
for weekdays.
Press and release. The display
shows WAKE and the time and
temperature you programmed for
heating.
Press and release so COOL
shows on the display, along with
the preprogrammed cooling
temperature.
If display reads SAT or SUN,
press and hold until MON TUE
WED THU FRI appears.
WAKE
SUN ON HEAT
WAKE
AM
SET
PT
M5031
SET
HEAT/COOL
SUN COOL
WAKE
AM
SET
PT
M5032
MON TUE WED THU FRI COOL
WAKE
AM
SET
PT
M5033
DAY
14