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T8624D Chronotherm

®

 IV Deluxe

Programmable Thermostat

PRODUCT DATA

® U.S. Registered Trademark
Copyright © 1997 Honeywell Inc.   •   All Rights Reserved

APPLICATION

The T8624D Chronotherm® IV Deluxe Programmable
Thermostat provides electronic control of 24 Vac multistage
heating and cooling systems.

FEATURES

Full seven-day program capability; different schedules
and temperature setpoints may be selected for
everyday to match the homeowner’s flexible schedule.

Copy key makes programming easier and faster for
the installer and homeowner.

Daylight Savings Time (DST) key for quick change in
and out of Daylight Savings Time.

Models available with programmable fan operation for
added homeowner comfort.

Easy temporary temperature setpoint changes for
current period, vacation hold (1 to 255 days) or
indefinite hold adds to the homeowner comfort and
energy savings.

Most frequently used keys are located by the Liquid
Crystal Display (LCD) for quick and easy access to
information.

Attractive styling complements any decor to the
homeowner’s delight.

Back lighting the large display makes the LCD very
easy to read.

Models available with outdoor temperature sensor
capability for homeowner convenience. The sensor is
also more accurate than a thermometer.

Configurable features allows one model to be used to
replace many different models (less inventory, no
longer need to carry separate models to get these
features).

°

F or 

°

C temperature display;

— automatic or manual changeover;
— electric or conventional heat fan operation;
— adjustable heating cycle rate.

Minimum off time for cooling compressors and heat
pumps protects the equipment and extends the
equipment life.

Easy installation, setup and system test saves
installer time and increases productivity.

System test simplifies troubleshooting and saves time
by overriding the time delays.

Adaptive Intelligent Recovery® control brings the
room temperature to temperature setpoint at the
programmed time, maximizing comfort and energy
savings.

Setpoints are permanently held in memory (no
batteries used) and retained during power outages for
increased installer and homeowner convenience.

Universal Versaguard™ Thermostat guards available
for added security.

Contents

General ...............................................................................

1

Features .............................................................................. 1
Specifications ......................................................................

2

Ordering Information ...........................................................

2

Installation ........................................................................... 3
Wiring .................................................................................. 4
Settings ...............................................................................

6

Installer Setup .....................................................................

7

Installer System Test ........................................................... 10
Programming ....................................................................... 12
Operation ............................................................................ 16
Troubleshooting Guide ........................................................ 18
Cross Reference ................................................................. 19
Wiring Diagram ................................................................... 20

68-0166-1

Summary of Contents for CHRONOTHERM IV DELUXE T8624D

Page 1: ... with outdoor temperature sensor capability for homeowner convenience The sensor is also more accurate than a thermometer Configurable features allows one model to be used to replace many different models less inventory no longer need to carry separate models to get these features F or C temperature display automatic or manual changeover electric or conventional heat fan operation adjustable heati...

Page 2: ...ide features listed in Table 1 Table 1 Thermostat Features Temperature Ratings Operating Ambient 40 F to 110 F 4 C to 43 C Shipping 30 F to 150 F 34 C to 65 C Display Accuracy 1 F 0 5 C Setpoint Range Heating 40 F to 90 F 7 C to 31 C Cooling 48 F to 99 F 9 C to 37 C Differential 3 F 1 5 C Default Settings see Table 3 Table 3 Default Setpoints Changeover System Selection Fan Selection Comments Auto...

Page 3: ...te horizontally on the wall or on a 2 in x 4 in wiring box 1 Position and level the wallplate for appearance only The thermostat will function properly even when not level 2 Use a pencil to mark the mounting holes See Fig 3 3 Remove the wallplate from the wall and drill two 3 16 inch holes in the wall if drywall as marked For firmer material such as plaster drill two 7 32 inch holes Gently tap anc...

Page 4: ...near each terminal for identification Refer to Table 4 for terminal designations CAUTION Disconnect power before wiring to prevent electrical shock or equipment damage 1 Loosen the terminal screws on the wallplate and connect the system wires See Fig 4 IMPORTANT Use 18 gauge color coded thermostat cable for proper wiring 2 Securely tighten each terminal screw 3 Push excess wire back into the hole ...

Page 5: ...er or changeover valve Output 24V powered contact C Ba C X1 X2 Common Input G F Fan relay Output 24V powered contact O R Cool damper or changeover valve Output 24V powered contact OT OT Outdoor temperature sensor C7089B Input R V 24V system or heating transformer Input RC 24V cooling transformer Input W1 H1 R3 Stage 1 heating relay Output 24V powered contact W2 H2 R4 W3 Y Stage 2 heating relay Out...

Page 6: ... as follows On Fan operates continuously Auto Fan operates with equipment Fig 7 T8624D System and Fan key locations Fig 6 T8624D key locations and descriptions M15042 Hold Temp Run Program Copy Daylight Time Set Current Day Time System Fan Time Set Program Day System Fan Wake Leave Return Sleep Heat Cool Settings M10405A Time Set Program System Fan Run Program Hold Temp Set Current Day Time Wake L...

Page 7: ...Setup feature To enter the Installer Setup press and hold the Information i key with the increase and decrease keys until the first number is displayed All display segments appear for approximately three seconds before the number is displayed See Fig 8 and 9 To advance to the next Installer Setup press the Time key Period Time Heat Setpoint Cool Setpoint Fan Setting Wake 6 00 AM 70 F 21 C 78 F 25 ...

Page 8: ...erature is displayed in F 1 Temperature is displayed in C Not used 15 Clock format 16 0 12 hour clock format 1 24 hour clock format Not used 17 and 18 Extended fan operation in heating 19 0 No extended fan operation after the call for heat ends 1 Fan operation is extended 90 seconds after the call for heat ends Extended fan operation in cooling 20 0 No extended fan operation after the call for coo...

Page 9: ...elect change Display Description Display Description Setting Not used 31 and 32 Minimum off time for the compressor 33 5 5 minute minimum off time for the compressor 0 thru 4 Minimum number of minutes 0 thru 5 the compressor will be off between calls for the compressor Temperature range stops in heating 34 90 Highest setpoint heating can be set to 40 to 89 Temperature range 1 F increments heating ...

Page 10: ...uto System Fan Wake Room AM DST Tue Heat INSTALLER SYSTEM TEST Use the Installer System Test to check the thermostat operation Refer to Table 7 for a list of the available system tests To start the system test CAUTION The minimum off time for compressors is bypassed during the Installer System Test Equipment damage can occur if the compressor is cycled too quickly Press and hold the increase and d...

Page 11: ...em fan turn off Cooling Equipment System Test Time 30 Change from heating to cooling equipment system test 31 Stage one cool and system fan come on 32 Stage two cool comes on Stage one cool and system fan remain on 31 Stage two cool turns off 30 Stage one cool and system fan turn off Fan Equipment SystemTest Time 40 Change from cooling to fan equipment system test 41 Fan comes on 40 Fan turns off ...

Page 12: ...g Monday Wake 6 00 AM 70 F 21 C 78 F 25 5 C Auto Leave 8 00 AM 62 F 16 5 C 85 F 29 5 C Auto Return 6 00 PM 70 F 21 C 78 F 25 5 C Auto Sleep 10 00 PM 62 F 16 5 C 82 F 28 C Auto Tuesday Wake 6 00 AM 70 F 21 C 78 F 25 5 C Auto Leave 8 00 AM 62 F 16 5 C 85 F 29 5 C Auto Return 6 00 PM 70 F 21 C 78 F 25 5 C Auto Sleep 10 00 PM 62 F 16 5 C 82 F 28 C Auto Wednesday Wake 6 00 AM 70 F 21 C 78 F 25 5 C Auto...

Page 13: ... Heat Cool Settings Daylight Time Daylight Time Copy AM DST Tue Set Day Time 4 Press Run Program M10316 Time Set Program System Fan Run Program Run Program Hold Temp Set Current Day Time Wake Leave Return Sleep Day Heat Cool Settings Daylight Time Copy Auto System Fan Wake Room AM DST Tue Heat M10317 Time Set Program System Fan Run Program Hold Temp Set Current Day Time Wake Wake Leave Return Slee...

Page 14: ...m the day displayed M10325 Time Set Program System Fan Run Program Hold Temp Set Current Day Time Wake Leave Return Sleep Day Day Heat Cool Settings Daylight Time Copy Heat Auto System Fan Wake Mon AM Set Program Start Time Setting Heat M10326 Time Set Program System Fan Run Program Hold Temp Set Current Day Time Wake Leave Return Sleep Day Heat Cool Settings Daylight Time Copy Copy Mon 4 Press Da...

Page 15: ...hange between heat and cool settings M10336 Time Set Program System Fan Run Program Hold Temp Set Current Day Time Wake Leave Return Sleep Day Heat Cool Settings Daylight Time Copy Cool Setting 4 Press increase or decrease key to adjust temperature settings M10336 Time Set Program System Fan Run Program Hold Temp Set Current Day Time Wake Leave Return Sleep Day Heat Cool Settings Daylight Time Cop...

Page 16: ...ad changes This is a phenomenon that most people in the industry know and accept Many factors contribute to offset including switch differential thermal lag overshoot cycle rates and system load The thermostat microprocessor simultaneously gathers compares and computes data Using this data it controls a wide variety of functions The special proprietary algorithm program in the thermostat eliminate...

Page 17: ...at is turned on a startup and initialization program begins The startup occurs only on initial powerup After total loss of power for an extended period the current time and day may need to be set but the user program is held See Table 11 for the default values NOTE Immediately following initialization the user can enter new setpoints to be used in place of the default values Period Time Heat Setpo...

Page 18: ...0 to 90 F 7 to 31 C Cooling limits are 48 to 99 F 9 to 37 C or the cooling lower The setpoint temperature range stops were configured Check Installer Setup numbers 34 and 35 and reconfigure the setpoint stops Heating or cooling come on momentarily and shut off Heat or cool circuit is opening up or becoming high impedance Add resistor in parallel with load or install interface relay System on indic...

Page 19: ...over to auto in Installer Setup 12 T8624D1063 Trane Premier White color T8624D2004 Wiring differences old new B C jumper R to Rc taupe color Symptom Possible Cause Action Cooling will not come on No power to the thermostat Check for 24 Vac between R and C If missing 24 Vac check if the circuit breaker is tripped reset the circuit breaker check if the system fuse is blown replace the fuse check if ...

Page 20: ...rol Honeywell Inc Honeywell Plaza P O Box 524 Minneapolis MN 55408 0524 Printed in U S A on recycled paper containing at least 10 post consumer paper fibers WIRING DIAGRAM FIG 14 Fig 14 Typical hookup of T8624D in multistage system W2 L1 HOT L2 M11309 FAN RELAY Y1 G C THERMOSTAT RC HEAT RELAY 1 R W1 L1 HOT L2 COMPRESSOR CONTACTOR 1 Y2 COMPRESSOR CONTACTOR 2 HEATING TRANSFORMER COOLING TRANSFORMER ...

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