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68-0134

C.H.  •  9-93  •  ©Honeywell Inc. 1993  •  Form Number 68-0134

The T8624C,D Chronotherm III Program-

mable Fuel Saver Thermostats provide auto-
matic control of multistage heating/cooling sys-
tems and offer users the highest standard of
comfort and convenience available with energy
savings.

Different schedules may be selected for week-
days, Saturday and Sunday.

Can be programmed in hand (with batteries in-
stalled) or on wall to provide up to four tempera-
ture settings per day.

Large digital clock (liquid crystal display) indi-
cates continuous time, day, current period and
room temperature.

Adaptive Intelligent Recovery™ brings room tem-
perature to programmed temperature at pro-
grammed time, maximizing comfort and energy
savings.

Temperature control program maintains tempera-
ture within 1

°

 F of setpoint.

Temporary program override available by using:

— WARMER and COOLER keys.
— SKIP next period key.
— CHANGE to last period key.

HOLD TEMP key provided for indefinite pro-
gram override (vacation/holiday).

Installer self-test and time delay override save
installation time.

SYSTEM light-emitting diode (LED) indicates
system is energized.

Models available with automatic or manual heat/
cool changeover.

Batteries included provide power to maintain
clock and memory during power failures.

Switching subbase with wiring terminals included.

Powered directly from control transformer, re-
quiring an extra (24V) wire to thermostat.

Fan operation switch to select either independent
or direct thermostat control of fan in heating
included on back of select models.

CONTENTS

Specifications ................................................. 2
Ordering Information ..................................... 2
Selection/Application ..................................... 4
Installation ..................................................... 5
Checkout ....................................................... 11
Programming the Thermostat ...................... 14
Operating the Thermostat ............................ 18
Troubleshooting ........................................... 21
Glossary ....................................................... 22

T8624C,D (5-1-1 Day

Programming) Chronotherm

®

III Fuel Saver Thermostats

Summary of Contents for CHRONOTHERM III T8624C

Page 1: ...nt Temporary program override available by using WARMER and COOLER keys SKIP next period key CHANGE to last period key HOLD TEMP key provided for indefinite pro gram override vacation holiday Installer self test and time delay override save installation time SYSTEM light emitting diode LED indicates system is energized Models available with automatic or manual heat cool changeover Batteries includ...

Page 2: ...ce can be expected if those conditions are changed TRADELINE MODELS TRADELINE models see Table 1 are selected and packaged to provide ease of stocking and handling and also maximum replacement value LIGHT EMITTING DIODE LED SYSTEM LED lights during thermostat ON cycle VOLTAGE RATING 15 to 30 Vac CURRENT RATING 1 6A maximum total per stage OPERATING HUMIDITY RANGE 5 to 90 percent relative humidity ...

Page 3: ...5 5 16 M5181A 4 3 32 104 1 31 32 50 Fig 2 Typical thermostat keypad SYSTEM RUN PROGRAM WAKE TIME TEMPERATURE PRESENT SETTING SKIP NEXT PERIOD CHANGE TO LAST PERIOD SET PRESENT DAY TIME HOLD TEMP DAY SET HEAT COOL SLEEP LEAVE AHEAD WARMER BACK COOLER M2998 WED LEAVE AM HEAT ON HEAT AUTO COOL ON AUTO FAN ROOM RETURN OFF PERIOD ...

Page 4: ... single speed fan Existing wiring Are there enough conductors to operate the equip ment and the thermostat Can a new cable be pulled IMPORTANT The T8624 requires an additional con ductor to transformer common to provide continu ous 24V power for thermostat operation SECURITY Does the thermostat selected provide access to Access Typical Application Device Free access to programming and adjustment o...

Page 5: ...rs or under cabinets hot or cold air from ducts radiant heat from sun or appliances concealed pipes and chimneys unheated uncooled areas such as an outside wall behind the thermostat REPLACING AN EXISTING THERMOSTAT Turn off thermostat power at furnace or boiler A two transformer system may require turning off two switches or disconnects Remove any existing wallplate or sub base from wall To avoid...

Page 6: ... the furnace or air conditioner The heating cycle rate of this thermostat is factory set for gas oil warm air heating The cooling cycle rate is factory set and cannot be adjusted The heating cycle rate can be adjusted by turning one or both cycle rate adjustment screws located on the back of the thermostat In multistage heat systems the cycle rate adjustment applies to the highest stage of heat on...

Page 7: ...ERCONNECTION M5233 HEATING TRANSFORMER R C W1 W2 HEAT RELAY 1 HEAT RELAY 2 COOLING TRANSFORMER Y1 G RC COOLING CONTACTOR FAN RELAY HEAT 1 HIGH LIMIT HIGH LIMIT L1 HOT L2 HEAT AUTO OFF SYSTEM SWITCH AUTO ON FAN SWITCH COOL HEAT 2 2 1 COOL L1 HOT L2 1 2 1 2 3 4 3 4 SUBBASE LOGIC CONTROL CIRCUIT POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED FOR SINGLE TRANSFORMER SYSTEM JU...

Page 8: ... COOL HEAT 2 COOL 2 COOL 1 SUBBASE LOGIC CONTROL CIRCUIT POWER SUPPLY PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED FOR SINGLE TRANSFORMER SYSTEM JUMPER R AND RC NOMINAL 24 Vac POWER MUST BE PRESENT BETWEEN R AND C FOR THERMOSTAT OPERATION AVAILABLE ON T8624D MODELS ONLY POWER SUPPLY THERMOSTAT LOGIC CIRCUIT 1 L1 HOT L2 2 L1 HOT L2 1 2 3 4 1 2 3 4 HEAT 1 5 5 Fig 7 T8624D 2 stage hea...

Page 9: ...GE 2 HEAT RELAY HEATING DAMPER OR CHANGEOVER RELAY COOLING TRANSFORMER O Y2 Y1 G RC STAGE 1 COOLING RELAY STAGE 2 COOLING RELAY COOLING DAMPER OR CHANGEOVER RELAY FAN RELAY HEAT 2 HEAT 1 HIGH LIMIT HIGH LIMIT L1 HOT L2 HEAT OFF COOL SYSTEM SWITCH COOL 1 COOL 2 AUTO ON FAN SWITCH L1 HOT L2 NON ELECTRIC ELECTRIC FAN OPERATION SWITCH 3 2 4 1 3 1 SUBBASE LOGIC CONTROL CIRCUIT 5 1 2 3 4 5 POWER SUPPLY ...

Page 10: ...the system will resume normal opera tion If the display goes off when power is lost either the backup batteries need to be replaced or are not installed When power is restored the display will flash 1 00 PM as a reminder to reprogram MOUNTING THE THERMOSTAT With system switch set to OFF hang the thermostat on the tabs at the top of the subbase Fig 11A Swing down and press on lower edge until therm...

Page 11: ...e set at least 3 F 2 C above the heating temperature or display will flash COOLING CAUTION Do not operate cooling if outdoor temperature is below 50 F 10 C Refer to manufacturer recommendations NOTE When cooling setting is changed thermostat will wait up to five minutes before turning on the cooling equipment This delay is to protect the com pressor Move the system switch to COOL and the fan switc...

Page 12: ...E LEAVE RETURN SLEEP TEMPORARY REPL BAT AM PM SET PT M410C continued RUN PROGRAM RUN PROGRAM SET HEAT COOL DAY SLEEP BACK COOLER AHEAD LEAVE WARMER RETURN WAKE T8624C D CHECKOUT 1 SET PRESENT DAY TIME SET PRESENT DAY TIME SET PRESENT DAY TIME SET PRESENT DAY TIME SET PRESENT DAY TIME System Press Look For This Response Switch Position This Key Key Down Key Released OFF 03 Blank 07 Blank 15 Blank C...

Page 13: ...egrees Clock hrs System Switch Position 0 F 12 COOL AUTO or OFF 1 F 24 COOL AUTO or OFF 2 F 12 HEAT 3 F 24 HEAT 4 C 12 COOL AUTO or OFF 5 C 24 COOL AUTO or OFF 6 C 12 HEAT 7 C 24 HEAT Second Stages of Digit Heat Cool 0 2 1 1 2 2 2 1 1 3 1 2 4 0 2 5 1 0 6 2 0 First Digit Cycle Rate Setting cph at 50 on time for stage 1 on 1 heat models stage 2 on 2 heat models 0 1 1 3 2 9 3 6 M5734 ...

Page 14: ...e 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 dis play shows the desired start ing time Press and hold until the dis play shows the desired tem perature If the display starts to blink while holding down TEM PE...

Page 15: ...m perature MON TUE WED THU FRI ON HEAT RETURN PM SET PT M5026 WARMER COOLER Program the SLEEP time and temperature if desired Press and release The dis play shows SLEEP and the pre programmed time and temperature Press and hold until the dis play shows the desired start ing time SLEEP RETURN MON TUE WED THU FRI ON HEAT SLEEP PM SET PT M5027 Press and hold until the display shows the desired temper...

Page 16: ...eating temperature For example if the heat ing setting is 70 F the mini If cooling temperatures are not being pro grammed skip Step 3 and press the RUN PROGRAM key STEP 3 SET THE COOLING TEMPERA TURES The program times are the same for both heating and cooling Only the cooling tem peratures need to be programmed if the thermostat has already been programmed for heating To set times as the cooling ...

Page 17: ...d until the dis play shows the desired tem perature Set the cooling temperatures for the SATURDAY schedule Use the same procedure as for weekdays Press and hold until SAT ap SAT COOL SLEEP PM SET PT M5041 LEAVE RETURN SLEEP WAKE WARMER COOLER DAY pears on the display Press WAKE LEAVE RETURN or SLEEP to select the time period Use the WARMER COOLER keys to set the temperature Set the cooling tempera...

Page 18: ...mperature COOL The thermostat controls your cooling system AUTO HEAT OFF COOL HEAT OFF COOL AUTO HEAT OFF COOL AUTO M3762 HEAT OFF COOL AUTO OFF Both the heating and cooling systems are off This completes the programming of the thermostat If the thermostat is removed from the wall to program replace it following the procedure on page 5 Operating the Thermostat TEMPORARILY CHANGING THE PROGRAM Thes...

Page 19: ... TEMP 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 hold down to alter nate between heating and cooling temperature settings Press and release to cancel hold ON HEAT SET PT M5048 ON HEAT SET PT M5049 ON HEAT SET PT M5050 WARMER COOLER PRESENT SETTING P...

Page 20: ...ease to display the next daily time and tem perature for that period Press and release to return to MON TUE WED THU FRI ON HEAT SLEEP PM SET PT M5054 LEAVE RETURN SAT ON HEAT SLEEP PM SET PT M5055 DAY MON M5056 RETURN PM RUN PROGRAM Press and release The dis play will show the current temperature setting for sev eral seconds then revert to the room temperature To check the heating and cooling sett...

Page 21: ...RMOSTAT NO DISPLAY SEE INSTALLATION INSTRUCTIONS FOR CORRECT MOUNTING PRESENT SETTING APPEARS INACCURATE THERMOSTAT IS IN RECOVERY MODE NORMAL OPERATION THERMOSTAT TURNS ON HEATING COOLING EARLY TO MEET TEMPERATURE SETTING AT PROGRAMMED TIMES RECOVERY CAN BE ENDED BY PUSHING WARMER COOLER KEYS CANNOT TEMPORARILY OVERRIDE BOTH HEATING AND COOLING SETTINGS IN AUTO MODE THERMOSTAT TEMPERATURE NEEDS T...

Page 22: ... higher temperature is the energy saving temperature Setpoint The thermostat temperature setting the homeowner selects The thermostat turns the heating or cooling equipment on and off to maintain this temperature at the thermostat location until another temperature setting setpoint goes into effect Sunday program schedule The schedule of WAKE LEAVE RETURN and SLEEP period start times and temperatu...

Page 23: ...23 68 0134 ...

Page 24: ...nd Building Control Home and Building Control Honeywell Inc Honeywell Limited Honeywell Limitée 1985 Douglas Drive North 740 Ellesmere Road Golden Valley MN 55422 Scarborough Ontario M1P 2V9 Printed in U S A ...

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