Honeywell T8624C Thermostat User Manual

T8624C,D (5-1-1 Day

Programming) Chronotherm

III Fuel Saver Thermostats

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.

■

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.

■

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.

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

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

68-0134

T8624C,D

SPECIFICATIONS • ORDERING INFORMATION

Specifications

IMPORTANT: The specifications given in this publi-

cation do not include normal manufacturing toler-

ances. Therefore, this unit may not exactly match

the listed specifications. Also, this product is tested

under closely controlled conditions, and some mi-

nor differences in performance can be expected if

those conditions are changed.

SETPOINT RANGE: 45° F to 88° F [7° C to 31° C].

CALIBRATION: Self-calibrating thermostat and

thermometer to ±1° F.

SHIPPING TEMPERATURE: -20° F to +120° F [-29° C

to +49° C].

CYCLES PER HOUR ADJUSTMENT:

Heating: First stage of 2-stage heat models—fixed at

cph. Second stage of 2-stage heat models or heat

TRADELINE MODELS

stage of single-stage heat models—factory-set at

6 cph; field-adjustable to 1,3,6 or 9 cph.

Cooling: Factory-set at 3 cph (not field adjustable);

minimum off-time of five minutes.

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.

FINISH: Beige matte with decorative brushed metal

faceplate or Premier White™.

VOLTAGE RATING: 15 to 30 Vac.

DIMENSIONS: Thermostat (mounted on subbase)—7 in.

[178 mm] long, 5-5/16 in. [135 mm] high, 1-3/4 in.

[44 mm] deep. See Fig. 1 for subbase dimensions.

TYPICAL KEYPAD: See Fig. 2.

CURRENT RATING: 1.6A maximum total per stage.

OPERATING HUMIDITY RANGE: 5 to 90 percent

relative humidity, noncondensing.

OPERATING AMBIENT TEMPERATURE RANGE:

ACCESSORIES:

TG586A Locking Cover.

0° F to 110° F [4° C to 43° C].

TG512 Versaguard™ Universal Thermostat Guard.

TABLE 1—TRADELINE MODELS.

Thermostat

Model

Number

Stages

Changeover

Type

Switching

System

Heat

Cool

Fan

Application

T8624C

T8624D

Auto

HEAT-AUTO-COOL-OFF

HEAT-OFF-COOL

ON-AUTO

Multistage

Manual

Ordering Information

When purchasing replacement and modernization products from your TRADELINE® wholesaler or your distributor, refer to the

TRADELINE Catalog or price sheets for complete ordering number, or specify—

. Model number.

. Number of heat and cool stages desired.

3. System, fan switching desired.

4. Application.

If you have additional questions, need further information or would like to comment on our products or services, please write or

phone:

. Your local Honeywell Home and Building Control Sales Office (check white pages of your phone directory).

. Home and Building Control Customer Satisfaction

Honeywell Inc., 1885 Douglas Drive North

Minneapolis, Minnesota 55422-4386 (612) 951-1000

In Canada—Honeywell Limited/Honeywell Limitee, 740 Ellesmere Road, Scarborough, Ontario M1P 2V9. International

Sales and Service offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France, Germany,

Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.

T8624C,D

SPECIFICATIONS

Fig. 1—T8624 Subbase mounting dimensions in in. [mm].

[

50]

[

46]

[

104]

135]

[

[83]

[121]

[179]

M5181A

Fig. 2—Typical thermostat keypad.

SYSTEM

ROOM

HEAT ON

WED

LEAVE

TEMPERATURE

PRESENT

SETTING

RUN

PROGRAM

PERIOD

TIME

SET

SKIP

PRESENT

DAY/TIME

WAKE

SLEEP

LEAVE

DAY

AHEAD

WARMER

COOLER

PERIOD

HOLD

TEMP

SET

HEAT/COOL

BACK

CHANGE

TO LAST

PERIOD

RETURN

FAN

HEAT AUTO COOL OFF

AUTO

M2998

68-0134

T8624C,D

SELECTION/APPLICATION

Selection/Application

The T8624 Thermostat uses the latest microelec-

tronic design and control technology to provide home

and building owners with the highest level of comfort

available and optimal energy savings in a package that is

easy to use and easy to live with.

The following section is a guide to selection and

application of the best thermostat to meet individual

needs.

— Fan switching; does fan come on automatically

from thermostat on cooling only (typical gas/

oil heating), or on call for cool and heat (typical

electric heat with 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.

PROGRAMMING

Does the thermostat selected accommodate the

customer’s daily schedule, lifestyle or work schedule?

Daily

Temperature

SECURITY

Does the thermostat selected provide access to

Device

Programming

Selection

T8624C,D

5-1-1 (Mon-Fri,

Sat, Sun)

4 heat and

4 cool

Typical

Application

Access

Device

Free access to

programming

and adjustment/ commercial

Home or

owner-occupied

T8624A,C,D

T8621A,C,D

7-day (each

day different)

4 heat and

4 cool

override.

building.

Restricted

access to

device.

Public

building.

T8624 with

TG512 Locking

Guard or

T8600,01,02,03* 5-1-1 (Mon-Fri,

Sat, Sun)

4 heat and

4 cool

TG586A

Locking Cover.

The choices are:

programmming and the override features that will best

suit the application? The choices are:

Model not currently available to control multistage

equipment.

SINGLE-STAGE HEAT PUMPS

If home/building owner has a single-stage heat pump,

one option is to use a T8624C or D (see Fig. 8).

IF NEW CONSTRUCTION APPLICATION, CON-

SIDER:

The T8624C is a two-stage heating, one-stage cool-

ing programmable thermostat. The T8624D is a two-

stage heating, two-stage cooling programmable thermo-

stat. What both thermostats have in common is separate

W1 and W2 (first and second stage heat) terminals. In

both cases, the W1 can be used for changeover in heat-

ing.

For single-stage compressor applications (both first-

•

Equipment type (see manufacturer specifications).

—

Staging required.

System switching required.

Fan switching required.

•

Control wiring—number of conductors required

to operate equipment and thermostat.

IMPORTANT: The T8624 requires an additional con-

stage heating and first-stage cooling energized through

ductor to transformer common to provide continu-

the Y terminal), simply jumper Y1 and W1.

Note that the recovery algorithm of the T8624 may

cause the compressor to cycle on and off during recov-

ous 24V power for thermostat operation.

IF RETROFIT/REPLACEMENT APPLICATION,

ery.

CONSIDER:

Equipment requirements.

Although the cycle rate for the first stages of heat and

cool are set for hot water systems, the second stage of the

T8624 must be adjusted. Turn the cycle rate adjustment

screws to the hot water setting on both the T8624C and

D to achieve the cycle rate appropriate for heat pumps.

If changeover is utilized in the cooling mode, apply a

normally closed relay.

•

—

Staging (heat stages, cool stages).

System switching (manual: HEAT-OFF-COOL;

automatic: HEAT-AUTO-COOL-OFF). Emer-

gency heat for heat pump application not pro-

vided on T8624.

The above application should be used only on single-

stage heat pumps.

T8624C,D

INSTALLATION

Installation

or disconnects. Remove any existing wallplate or sub-

base from wall. To avoid miswiring later, label each

wire color with the letter or number on the wiring termi-

nal as the wire is removed.

RECYCLING NOTICE

If this control is replacing a control that contains

mercury in a sealed tube, do not place your old control in

the trash. Contact your local waste management author-

ity for instructions regarding recycling and the proper

disposal of your old control.

NEW INSTALLATION

Run cable to a hole at the selected wall location for the

thermostat, and pull about 3 in. [76 mm] of wire through

the opening. Color-coded, 18-gauge thermostat cable with

at least one conductor for each wiring terminal is recom-

mended. Good service practice recommends selecting

cable with one or two more conductors than the immedi-

ate application requires.

If you have any questions, call Honeywell Inc. at 1-

00-468-1502.

COMPATIBILITY

The T8624 Thermostats will replace most heating/

cooling system thermostats. As long as ac power is

continuously available to the transformer, the thermostat

will be compatible with any low-volt control system.

MOUNTING SUBBASE

IMPORTANT: Before mounting, set the system switch

IMPORTANT: The T8624 requires an additional con-

ductor to transformer common to provide continu-

ous 24V power for thermostat operation.

to the OFF position.

NOTE: The subbase does not require leveling for proper

operation, but only for appearance.

WHEN INSTALLING THIS PRODUCT…

. Read these instructions carefully. Failure to follow

them could damage the product or cause a hazardous

condition.

Fig. 3—Removing thermostat from subbase.

. Check the ratings given on the product to make

sure the product is suitable for your application.

. Installer must be a trained, experienced service

technician.

. Allow thermostat to warm to room temperature

before operating.

. After installation is complete, check out product

operation as provided in these instructions.

CAUTION

HEAT AUTO COOL

OFF

FAN

AUTO

Disconnect power supply to prevent electrical

shock or equipment damage.

M 844

LOCATION

Install thermostat and subbase about 5 ft [1.5m] above

the floor in an area with good air circulation at room

temperature.

Do not install thermostat where it may be affected by:

—

drafts or dead spots behind doors, in corners 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.

Remove thermostat from subbase (Fig. 3).

Mount the subbase directly onto the wall with the

screws and anchors included. If drywall construction,

use plastic anchors. Use the subbase as a template, and

with a pencil, mark the two mounting screw positions

—

(Fig.

4).

Use

3/16 in. bit to drill holes for anchors. Gently tap anchors

into holes until they are flush with the wall surface.

Thread wires through the center opening of the subbase.

Then mount the subbase using the two screws provided.

Gently tighten the screws, level the top surface of the

subbase, and securely tighten the screws.

REPLACING AN EXISTING THERMOSTAT

Turn off thermostat power at furnace or boiler. A two-

transformer system may require turning off two switches

68-0134

T8624C,D

INSTALLATION

Fig. 4—Mounting subbase on wall.

Fig. 5—Restrict wiring to recessed area

surrounding terminals.

WALL

FOR STRAIGHT

INSERTION –

STRIP 5/16 in. [8 mm]

WIRES THROUGH

WALL OPENING

FOR WRAPAROUND –

STRIP 7/16 in. [11 mm]

RESTRICT

WIRING TO

THIS AREA

FRONT VIEW OF

TERMINAL AREA

WALL

ANCHORS

(

WIRING TO BE BELOW

THIS SURFACE

TOP SURFACE

OF SUBBASE

MOUNTING

HOLES

MOUNTING

SCREWS (2)

SUBBASE

CROSS-SECTIONAL VIEW OF

TERMINAL AREA

M 847

M846

WIRING

In multistage heat systems, the cycle rate adjustment

applies to the highest stage of heat only. Screws should

be backed out about one-half to one turn, or be turned in

until tight. See Fig. 9.

All wiring must comply with local electrical codes

and ordinances.

Disconnect power before wiring to prevent electrical

shock or equipment damage.

The shape of the terminal barrier permits insertion of

straight or conventional wraparound wiring connections.

Either method is acceptable.

Push excess wire back into the hole, and plug the hole

with nonhardening caulk, putty or insulation to prevent

drafts from affecting thermostat operation.

TIME/TEMPERATURE CONVERSION

(SOME MODELS)

The display readout may be converted between 12

and 24 hour clock or °C and °F using screws 2A and 2B

as indicated in Fig. 9.

FAN OPERATION OPTION SWITCH

(SELECT MODELS ONLY)

NOTE: Restrict wiring to the recessed area surrounding

the terminals (Fig. 5) to assure thermostat/subbase

contact.

Select models include a fan operation option switch

on the subbase that is visible before the thermostat is

mounted on the subbase. The switch should be in electric

heat position for electric heating systems that do not

have independent fan control.

Refer to Figs. 6-8 for typical hookups of subbase and

thermostat.

ADJUSTING CYCLE RATE

INSTALLING BATTERIES

To customize the thermostat cycling performance to

various types of heating equipment, cycle rate adjust-

ment screws are provided on the back of the thermostat

to provide optimum room temperature control.

Three AAA alkaline batteries are included to provide

backup to prevent program loss in case of power outage.

Install batteries in back of thermostat as shown in Fig.

Without battery backup, the program will remain

NOTE: Most applications will not require a change in

cycle rate.

about 30 seconds in event of power loss.

IMPORTANT: When batteries are first installed, the

display will flash 1:00 PM and 32°. The tempera-

ture will stay at 32° F until the thermostat is

powered from the system wiring.

The room air temperature will normally vary slightly

from the comfort temperature setting with the cycling of

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.

When the batteries are low, the display will flash

REPL BAT. Homeowner will have 20-30 seconds to

install new batteries after removing old batteries from

back of thermostat. After 20-30 seconds, it will be nec-

essary to reprogram. REPL BAT indication will disap-

T8624C,D

INSTALLATION

Fig. 6—T8624C 2-stage heat/1-stage cool thermostat with HEAT-AUTO-COOL-OFF system and AUTO-ON

fan switching.

HEATING

TRANSFORMER

(HOT)

HIGH

LIMIT

POWER

SUPPLY

HIGH

LIMIT

HEAT 1

HEAT 2

HEAT RELAY 1

HEAT RELAY 2

SYSTEM

SWITCH

HEAT

THERMOSTAT

LOGIC CIRCUIT

AUTO

COOL

OFF

COOLING

COOL

CONTACTOR

FAN

SWITCH

SUBBASE

LOGIC/

CONTROL

CIRCUIT

FAN RELAY

AUTO

(HOT)

COOLING

TRANSFORMER

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD

PROTECTION AS REQUIRED.

NOMINAL 24 Vac POWER MUST BE PRESENT BETWEEN R AND C FOR

THERMOSTAT OPERATION.

FOR SINGLE TRANSFORMER SYSTEM JUMPER R AND RC.

DENOTES THERMOSTAT TO SUBBASE INTERCONNECTION.

M5233

68-0134

T8624C,D

INSTALLATION

Fig. 7—T8624D 2-stage heat/2-stage cool thermostat with HEAT-AUTO-COOL-OFF system and AUTO-ON

fan switching.

(HOT)

HIGH

LIMIT

HEATING

TRANSFORMER

HEAT RELAY 1

POWER

SUPPLY

HIGH

LIMIT

HEAT 1

HEAT 2

SYSTEM

SWITCH

HEAT RELAY 2

HEAT

THERMOSTAT

LOGIC

CIRCUIT

AUTO

COOL

OFF

COOLING

CONTACTOR 2

COOL 2

COOL 1

SUBBASE

LOGIC/

CONTROL

CIRCUIT

FAN

SWITCH

COOLING

CONTACTOR 1

AUTO

FAN RELAY

POWER SUPPLY. PROVIDE DISCONNECT MEANS

AND OVERLOAD PROTECTION AS REQUIRED.

(HOT)

FOR SINGLE TRANSFORMER SYSTEM, JUMPER R AND RC.

COOLING

TRANSFORMER

NOMINAL 24 Vac POWER MUST BE PRESENT BETWEEN

R AND C FOR THERMOSTAT OPERATION.

DENOTES THERMOSTAT TO SUBBASE INTERCONNECTION.

AVAILABLE ON T8624D MODELS ONLY.

M3765

T8624C,D

INSTALLATION

Fig. 8—T8624D 2-stage heat/2-stage cool thermostat with HEAT-OFF-COOL system and AUTO-ON fan

switching; auto fan on heat and cool; convertible to auto fan on cool only.

HOT) L2

(

HEATING

TRANSFORMER

POWER

SUPPLY

HIGH

LIMIT

FAN

OPERATION

SWITCH

HIGH

LIMIT

STAGE 1

ELECTRIC

HEAT RELAY

HEAT 1

HEAT 2

NON-ELECTRIC

SYSTEM

SWITCH

STAGE 2

HEAT RELAY

HEAT

THERMOSTAT

LOGIC CIRCUIT

OFF

HEATING DAMPER OR

CHANGEOVER RELAY

COOL

COOLING DAMPER OR

CHANGEOVER RELAY

STAGE 2

COOLING RELAY

COOL 1

COOL 2

STAGE 1

COOLING RELAY

SUBBASE

LOGIC/

CONTROL

CIRCUIT

FAN

SWITCH

FAN RELAY

AUTO

COOLING

TRANSFORMER

(HOT)

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD

PROTECTION AS REQUIRED.

FOR ELECTRIC HEAT APPLICATIONS (AUTO FAN OPERATES WITH W1

AND Y1), USE ONLY ONE TRANSFORMER; JUMPER R AND RC. SET

SWITCH TO ELECTRIC POSITION.

FOR GAS OR OIL APPLICATIONS OR ELECTRIC HEAT APPLICATIONS

WHERE THE FAN OPERATION IS CONTROLLED INDEPENDENTLY OF

THE THERMOSTAT (AUTO FAN OPERATES WITH Y1 ONLY), TWO

TRANSFORMERS MAY BE USED. SET SWITCH TO NONELECTRIC

POSITION.

NOMINAL 24 VAC POWER MUST BE PRESENT BETWEEN R AND C FOR

THERMOSTAT OPERATION.

DENOTES THERMOSTAT TO SUBBASE INTERCONNECTION.

M1016D

68-0134

T8624C,D

INSTALLATION

After replacing the batteries, reprogramming will be nec-

essary.

Fig. 9—Cycle rate adjustment.

BATTERY PLACEMENT

(

NOTE CORRECT PLUS

CYCLES

PER HOUR

TIME/TEMP

DISPLAY

AND MINUS DIRECTION)

M 372A

SYSTEM

GRAVITY

OUT 1/2

AIR/WATER TO 1 TURN TO 1 TURN

24 HR

12 HR

HOT

WATER

OUT 1/2

TO 1 TURN

OUT 1/2

TO 1 TURN

GAS/OIL

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.

WARM AIR (FACTORY SETTING)

ELECTRIC

WARM AIR

OUT 1/2

TO 1 TURN

OUT 1/2

TO 1 TURN

SCREWS 2A, 2B AVAILABLE ON SOME MODELS ONLY.

M311A

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 thermostat snaps in

place (Fig. 11B). Open cover and tighten the captive

mounting screws (Fig. 11C).

pear when thermostat is mounted back on the subbase.

IMPORTANT: For proper thermostat operation, al-

ways replace dead batteries with new alkaline

batteries. We recommend Energizer® batteries.

SETTING DAY AND TIME

Restore 24V power to the thermostat. When power is

applied to the thermostat, the display will read 1:00 PM

and room temperature. It will go off for a few seconds,

then begin to flash on and off. Set present day and time.

If batteries are completely dead, the display will go

blank when the thermostat is removed from the subbase.

Fig. 10—Battery placement.

SET

PRESENT

POWER OUTAGES

Press DAY/TIME

Backup batteries will hold the programming and keep

the display on during most power outages. Once the

power is restored, the system will resume normal opera-

tion.

Press

DAY

to set the current day. Each press of

the DAY key advances the display one day.

BACK

Press TIME

to set the current time.

AHEAD

If the display will not come on:

—

Check the mounting of the thermostat to the sub-

base. If loose or misaligned, remove thermostat

and reinstall on the subbase, making sure it is

firmly attached.

—

Check to see that heat or cool system power is on.

Check voltage between R and C; it should be 24 to

0 Vac.

T8624C,D

INSTALLATION • CHECKOUT

Fig. 11—Mounting thermostat on subbase.

SYSTEM

RETU RM ON

HEAT ON

FAN

AUTO

ON AUTO

HEAT AUTO COOL

OFF

SYSTEM

RETU RM ON

HEAT ON

TEMPERATURE

PR OR GU RN AM

ET ST EI N

PERIOD

LEAVE

TIME

DP RA SEY ES/ T TEI MN ET

HT EO ML DP

P NES ERK XII OP

DAY

WAKE

SLEEP

AHEAD

BACK

WARMER

COOLER

SET

HEAT/COOL

RETURN

CT OH A

GS ET

PERIOD

M3764

Checkout

HEATING

Move the system switch to COOL and the fan switch

Move the system switch to HEAT and the fan switch

to AUTO. Press WARMER key until the setting is about

to AUTO. Press COOLER key until the setting is about

10° F [6° C] below room temperature. The cooling

equipment and fan should start (both stages if multi-

stage). Press WARMER key until the setting is about

10° F [6° C] above room temperature. The cooling

equipment and fan equipment should stop.

0° F [6° C] above room temperature. Heating should

start (both stages if multistage), and the fan should run

may be a short delay on forced air systems). Press

(

COOLER key until the setting is about 10° F [6° C]

below room temperature. The heating equipment should

shut off, followed by the fan.

NOTE: On an AUTO changeover thermostat, the heat-

ing temperature must be set at least 3° F [2° C] below

the cooling temperature, or display will flash.

NOTE: On an AUTO changeover thermostat, the cool-

ing temperature must be set at least 3° F [2° C] above

the heating temperature, or display will flash.

FAN

Move the system switch to OFF, and the fan switch to

ON. The fan should run continuously. When the fan

switch is in the AUTO position, the fan operates directly

with the thermostat call for cooling and also with the

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.

68-0134

T8624C,D

CHECKOUT

System

Switch

Position

Press

This

Key

Look For This Response

Key

Down

Key Released

OFF

Blank

WARMER

COOLER

Blank

AHEAD

BACK

Blank

LEAVE

RETURN

WAKE

REPL

PM BAT

SET

SUN MON TUE WED THU FRI SAT COOL ON HEAT ON

Blank

WAKE LEAVE RETURN SLEEP TEMPORARY

M410C

(

CHECK

See note AA

EACH

POSITION)

OFF

Blank

SLEEP

DAY

Microprocessor

mask no. and

revision no.

RUN

PROGRAM

SET

HEAT/COOL

Blank

Look For This Response

System

Switch

Position

Press

This

Key

SET

PRESENT

DAY/TIME

Blank

Key

Down

Key Released

Blank

HEAT or

AUTO

SET

PRESENT

DAY/TIME

1st stage heating

and SYSTEM

LED on.

OFF

CHANGE

TO LAST

PERIOD

SKIP

PERIOD

Blank

SET

PRESENT

DAY/TIME

2nd stage heating

also on.

PRESENT

SETTING

SET

PRESENT

DAY/TIME

2nd stage heating

off.

COOL or

AUTO

with fan in

PRESENT

SETTING

1st stage cooling,

fan and SYSTEM

LED on.

SET

PRESENT

DAY/TIME

1st stage heating

and SYSTEM

LED off.

(

AUTO)

2nd stage cooling

also on.

PRESENT

SETTING

NOTE: If single-stage heating system, press key twice

instead of four times; once to turn on heating and

SYSTEM LED, second time to turn off.

PRESENT

SETTING

2nd stage cooling

off.

OFF

HOLD

TEMP

Blank

PRESENT

SETTING

1st stage cooling,

fan and SYSTEM

LED off.

RUN

PROGRAM

Normal operating

display.

NOTE: If single-stage cooling system, press key twice

instead of four times; once to turn on cooling, fan

and SYSTEM LED, second time to turn off.

END SELF-TEST

(

continued)

T8624C,D

CHECKOUT

Second

Digit

Stages of

Heat

Cool

Cycle Rate Setting (cph at 50% on

time for stage 1 on 1-heat models,

stage 2 on 2-heat models)

First Digit

M5734

Third

Digit

Manual or Auto

Changeover

System Switch

Position

Fourth

Digit

Clock

(hrs)

System Switch

Position

Degrees

Manual

Auto

HEAT or OFF

AUTO

COOL, AUTO

or OFF

COOL, AUTO

or OFF

Auto

Manual

Auto

COOL

HEAT

COOL

COOL, AUTO

or OFF

COOL, AUTO

or OFF

HEAT

68-0134

T8624C,D

PROGRAMMING THE THERMOSTAT

Programming the Thermostat

IMPORTANT: With Adaptive Intelligent Recovery™,

program the times for when the homeowner wants

the 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 op-

erating on backup batteries until the thermostat is

mounted on the wallplate and the system is powered.

STEP 1

SET THE CURRENT DAY AND

TIME

SET

PRESENT

DAY/TIME

definitions of unfamiliar

words.

MON

M5015

This thermostat can be programmed either

on the wall or in hand. SEE PAGE 5 TO

FIND OUT HOW TO REMOVE THE

THERMOSTAT FROM THE SUBBASE.

Press and release. The display

shows 1:00 PM MON.

DAY

TUE

M5016

M5017

Press and hold until the current

day appears in the display.

AHEAD

BACK

TUE

Always press the keys with fingertip or

similar blunt tool. Sharp instruments like a

pen or pencil point can damage the key-

board.

Press and hold until the current

time appears in the display. Be

sure AM or PM appears as desired.

NOTE: Check the glossary, page 22, for

STEP 2

SET THE PROGRAM SCHEDULE

AND HEATING TEMPERATURES

Press and release. Note that

the display shows WAKE and

SET

WAKE

MON TUE WED THU FRI

ON HEAT

WAKE

the preprogrammed time and

temperature.

M5018

Before Beginning…

The schedule form on page 22 provides the

homeowner an opportunity to plan the

schedule.

If the display reads COOL,

press and release to switch to

SET

HEAT/COOL

SET

MON TUE WED THU FRI

ON HEAT

WAKE

HEAT.

M5018

Now…

Start by programming the WAKE time

and temperature for weekdays.

If display reads SAT or SUN,

press and hold until MON

SET

DAY

MON TUE WED THU FRI

ON HEAT

WAKE

TUE WED THU FRI appears.

M5018

The thermostat requires a program for

WAKE. You can program LEAVE, RE-

TURN and SLEEP or not, as desired.

Press and hold until the dis-

play shows the desired start-

ing time.

SET

AHEAD

BACK

MON TUE WED THU FRI

WAKE

ON HEAT

M5019

Press and hold until the dis-

play shows the desired tem-

perature.

SET

WARMER

COOLER

MON TUE WED THU FRI

WAKE

ON HEAT

M5020

If the display starts to blink while holding down TEM-

PERATURE WARMER or COOLER, the setting limit

has been reached. If the thermostat can switch automati-

cally between heating and cooling, the heating tempera-

ture must be at least three degrees below the air condi-

tioning temperature. For example, if the cooling setting

T8624C,D

PROGRAMMING THE THERMOSTAT

is 75° F, the maximum heating setting is

2° F.

temperature disappear from

the display.

SET

LEAVE

MON TUE WED THU FRI

LEAVE

ON HEAT

Program the LEAVE time and tempera-

ture, if desired.

M5021

Press and release. The display

shows LEAVE, but no time

or temperature.

SET

NOTE: The LEAVE, RETURN or SLEEP

program may be canceled by holding

down the period key until the time and

AHEAD

BACK

MON TUE WED THU FRI

LEAVE

ON HEAT

M5022

Press and hold until the dis-

play shows the desired starting time.

SET

WARMER

COOLER

MON TUE WED THU FRI

LEAVE

ON HEAT

M5023

Press and hold until the display shows the

desired temperature.

Press and release. The display

shows RETURN, but no time

or temperature.

SET

RETURN

MON TUE WED THU FRI

RETURN

ON HEAT

M5024

Program the RETURN time and tempera-

ture, if desired.

Press and hold until the dis-

play shows the desired start-

ing time.

SET

MON TUE WED THU FRI

RETURN

AHEAD

BACK

ON HEAT

M5025

SET

MON TUE WED THU FRI

RETURN

WARMER

COOLER

Press and hold until the dis-

play shows the desired tem-

perature.

ON HEAT

M5026

Program the SLEEP time and temperature, if desired.

SLEEP

MON TUE WED THU FRI

SP ET T

Press and release. The dis-

ON HEAT

play shows SLEEP and the

pre-programmed time and

temperature.

SLEEP

M5027

SET

MON TUE WED THU FRI

AHEAD

BACK

ON HEAT

Press and hold until the dis-

play shows the desired start-

ing time.

SLEEP

M5060

SET

MON TUE WED THU FRI

SLEEP

WARMER

COOLER

ON HEAT

M5028

Press and hold until the display shows the

desired temperature.

Set the SATURDAY sched-

ule. Use the same procedure

as for weekdays.

SET

SAT

DAY

ON HEAT

SLEEP

M5029

WAKE

SLEEP

LEAVE

Press and release until SAT ap-

pears on the display.

RETURN

Press WAKE, LEAVE, RE-

TURN or SLEEP to select the

time period.

AHEAD

BACK

WARMER

COOLER

Use the AHEAD/BACK keys

to set the time and the WARMER/COOLER

keys to set the temperature.

Set the SUNDAY schedule.

Use the same procedure as for

weekdays.

SET

DAY

SUN

ON HEAT

SLEEP

M5030

68-0134

T8624C,D

PROGRAMMING THE THERMOSTAT

WAKE

SLEEP

LEAVE

Press and hold until SUN ap-

pears on the display.

RETURN

Press WAKE, LEAVE, RE-

TURN or SLEEP to select

the time period.

AHEAD

BACK

WARMER

COOLER

Use the AHEAD/BACK keys

to set the time and the

WARMER/COOLER keys to set the temperature.

This completes setting the program schedule and heat-

ing temperatures. To set air conditioning, go to Step 3.

If cooling temperatures are not being pro-

grammed, skip Step 3 and press the RUN

PROGRAM key.

SET

WAKE

First program the WAKE tem-

perature for weekdays.

SUN

ON HEAT

WAKE

M5031

STEP 3

SET THE COOLING TEMPERA-

TURES

Press and release. The display shows WAKE and the

time and temperature pro-

SET

HEAT/COOL

SET

grammed for heating.

SUN

COOL

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

temperatures are programmed, use the TIME

AHEAD and BACK keys as described in

Step 2. If the times are changed for cooling,

they are also being changed for heating.

WAKE

M5032

Press and release so COOL

shows on the display, along

with the preprogrammed cool-

ing temperature.

SET

DAY

MON TUE WED THU FRI

WAKE

COOL

M5033

If display reads SAT or SUN,

press and hold until MON

TUE WED THU FRI appears.

SET

WARMER

COOLER

MON TUE WED THU FRI

COOL

WAKE

M5034

Press and hold until the dis-

play shows the desired temperature.

If the display blinks while holding down TEMPERA-

TURE WARMER or COOLER, the setting limit has

been reached. If the thermostat can switch automatically

between heating and cooling, the cooling temperature

must be at least three degrees higher than the corre-

sponding heating temperature. For example, if the heat-

ing setting is 70° F, the mini-

mum

cooling

setting

desired, the heating tempera-

ture first must be lowered ac-

cordingly.

SET

LEAVE

3° F. If a lower cooling temperature is

MON TUE WED THU FRI

LEAVE

COOL

M5035

Program the LEAVE tempera-

ture, if desired.

SET

WARMER

COOLER

MON TUE WED THU FRI

LEAVE

COOL

Press and release. The display

M5036

shows LEAVE, the time programmed for

heating, and

8° F.

RETURN

MON TUE WED THU FRI

RETURN

SP ET T

Press and hold until the dis-

play shows the desired tem-

perature.

COOL

M5037

T8624C,D

PROGRAMMING THE THERMOSTAT

Program the RETURN tem-

SET

MON TUE WED THU FRI

RETURN

WARMER

COOLER

perature,

desired.

COOL

M5038

Press and release. The display shows RE-

TURN, the time programmed for heating,

SET

SLEEP

MON TUE WED THU FRI

SLEEP

78° F.

COOL

M5039

Press and hold until the

display shows the desired tem-

perature.

SET

MON TUE WED THU FRI

SLEEP

WARMER

COOLER

COOL

M5040

Program the SLEEP tempera-

ture, if desired.

SET

SAT COOL

DAY

SLEEP

Press and release.

Press and hold until the dis-

play shows the desired tem-

perature.

M5041

WAKE

SLEEP

LEAVE

Set the cooling temperatures

for the SATURDAY schedule.

Use the same procedure as for

weekdays.

RETURN

WARMER

COOLER

Press and hold until SAT ap-

pears on the display.

to select the time period.

SET

DAY

SUN

COOL

SLEEP

M5042

Press WAKE, LEAVE, RETURN or SLEEP

WAKE

SLEEP

LEAVE

Use the WARMER/COOLER

keys to set the temperature.

RETURN

Set the cooling temperatures for

the SUNDAY schedule. Use the

same procedure as for weekdays.

WARMER

COOLER

Press and hold until SUN ap-

pears on the display.

Press WAKE, LEAVE, RE-

TURN or SLEEP to select the

time period.

RUN

PROGRAM

SET

TUE

LEAVE

M5043

68-0134

T8624C,D

PROGRAMMING THE THERMOSTAT • OPERATING THE THERMOSTAT

Use the WARMER/COOLER keys to set the tempera-

ture.

SET THE SYSTEM AND FAN

SWITCHES ON THE SUB-

BASE.

FAN

AUTO

You have completed programming the cooling tempera-

tures.

Depending on thermostat model,

some of the switch positions shown

may not be available on the ther-

mostat. Note the positions provided

on the subbase, then set the

switch(es) as desired.

FAN

Press and release to start the program.

AUTO

Go to Step 4.

M3763

STEP 4

First set the fan switch.

FAN ON: The fan runs continuously. Use for improved

air circulation during special occasions or for more effi-

cient

electronic

air

cleaning.

FAN AUTO: Normal setting

for most homes. The fan goes

on and off with the air condi-

tioner in summer. In winter, the

HEAT

AUTO COOL OFF

fan

most

systems starts a few minutes

after the furnace comes on. It

stops a few minutes after the

furnace goes off. The fan starts

and stops with the furnace in

some electric heat systems and

with the compressor in heat

pump systems.

HEAT AUTO COOL OFF

Then set the system switch.

HEAT AUTO

COOL OFF

M3762

HEAT: The thermostat controls

your heating system.

AUTO (select models only): The thermostat controls

either your heating or cooling system, depending on

room temperature.

OFF: Both the heating and cooling systems are off.

This completes the programming of the thermostat.

OpeCOOL: The thermostat controls your cooling system.

rating the Thermostat

If the thermostat is removed from the wall to program, replace it following the procedure on page 5.

TEMPORARILY CHANGING THE PROGRAM

These features allow the program to be customized for

those times when someone comes home early, or stays

up late, or plans to be out for the evening.

To keep the current temperature through the

next program period:

Press and release. The name

of the period to be skipped

will flash in the display until

the next regularly scheduled

period starts.

SKIP

PERIOD

TUE

LEAVE RETURN

M5044

To go back to the temperature of the previ-

ous program period:

Press and release. The dis-

play will show the name of

the previous period and flash

TEMPORARY until the next

regularly scheduled period starts.

CHANGE

TO LAST

PERIOD

TUE

WAKE

TEMPORARY

M5045

T8624C,D

OPERATING THE THERMOSTAT

To temporarily raise or lower the tempera-

ture for the current period only:

Press and hold until the de-

WARMER

COOLER

sired temperature is reached.

The display will flash TEM-

PORARY until the next pro-

grammed time period starts.

ON HEAT

TEMPORARY

M5046

With the system switch at the

AUTO position, press and

hold down the key to alter-

nate between heating and cool-

ing temperature settings for

temporary override.

PRESENT

SETTING

Press and release to cancel

any of the temporary settings.

RUN

PROGRAM

TUE

LEAVE

M5047

PERMANENTLY CHANGING THE

PROGRAM

WAKE

SLEEP

LEAVE

Press and release the desired

period key.

If the schedule changes or a different tem-

perature is desired, any setting can be up-

dated without affecting other program set-

tings.

RETURN

DAY

Press and hold until the desired

day schedule shows on the dis-

play.

AHEAD

BACK

Press and hold the Time or Tem-

perature keys until the display

shows the desired new program.

WARMER

COOLER

RUN

PROGRAM

Press and release to return to

normal operation.

HOLD

TEMP

SET

MANUALLY OPERATING THE

THERMOSTAT

Press and release.

ON HEAT

M5048

This feature is particularly useful when on

vacation or other extended absences. It does

not cancel the program.

SET

WARMER

COOLER

Press and hold to change the

temperature setting. After a

few seconds, the display will

show the current temperature.

ON HEAT

M5049

PRESENT

SETTING

SET

Press and release to check the

temperature setting.

ON HEAT

M5050

Press and hold down to alter-

nate between heating and

cooling temperature settings.

RUN

PROGRAM

Press and release to cancel

hold.

TUE

LEAVE

M5051

68-0134

T8624C,D

OPERATING THE THERMOSTAT

NOTE: Moving the system switch also can-

cels hold.

CANCELING THE PROGRAM

SETTINGS

day and Sunday settings are

canceled separately.

SLEEP

MON TUE WED THU FRI

LEAVE

ON HEAT

M5052

Press and hold the desired pe-

riod key until the time and temperature clear from the

display (about three seconds).

LEAVE

The thermostat requires time and tempera-

ture settings in the WAKE period, but any of

the others can be canceled. Weekday, Satur-

RETURN

RUN

PROGRAM

MON

RETURN

Press and release to return to

M5053

Check all the stored settings without affecting the per-

normal operation.

manent program.

SET

WAKE

SLEEP

LEAVE

MON TUE WED THU FRI

SLEEP

ON HEAT

CHECKING THE PROGRAM TIMES

AND TEMPERATURES

Press and release the desired

period key. The start time and

M5054

temperature setting will appear on the display.

RETURN

DAY

SET

Press and release to display

the next daily time and tem-

perature for that period.

SAT

ON HEAT

SLEEP

M5055

RUN

PROGRAM

Press and release to return to

MON

normal operation.

RETURN

M5056

PRESENT

SETTING

SET

CHECKING THE CURRENT

TEMPERATURE SETTING

Press and release. The dis-

play will show the current

temperature setting for sev-

ON HEAT

M5057

Press a single key to compare current room

temperature to the current temperature set-

ting at any time.

eral seconds, then revert to the room temperature.

To check the heating and cooling settings with the sys-

tem switch at the AUTO position, press and hold down

to alternate between the heating and cooling settings.

PRESENT

SETTING

During recovery from energy savings, the setting dis-

played will not match the programmed setting. This is

because the thermostat gradually changes the tempera-

ture setting during recovery to provide most efficient use

of the heating or cooling equipment.

T8624C,D

TROUBLESHOOTING

SYMPTOM

POSSIBLE CAUSE

ACTION

CHECK POWER TO FURNACE OR AIR CONDITIONER.

ROOM TEMPERATURE DISPLAY

_I_S₃₂˚

NO ac POWER TO THERMOSTAT

–

ON-OFF SWITCH

FUSE OR CIRCUIT BREAKER

LOOSE 24V CONNECTION

–AT THERMOSTAT

–AT FURNACE /AIR CONDITIONER

–INCORRECT WIRING

–CHECK WIRING DIAGRAM

FURNACE OR AIR CONDITIONER

WON'T OPERATE.

NO ac POWER TO THERMOSTAT

CHECK POWER TO FURNACE OR AIR CONDITIONER.

–

ON-OFF SWITCH

FUSE OR CIRCUIT BREAKER

LOOSE 24V CONNECTION

–AT THERMOSTAT

–AT FURNACE /AIR CONDITIONER

–INCORRECT WIRING

–CHECK WIRING DIAGRAM

THERMOSTAT INOPERATIVE

CONDUCT SELF-TEST; SEE CHECKOUT.

ADJUST TEMPERATURE BY PUSHING WARMER/

COOLER KEYS.

PRESENT SETTING TOO LOW/HIGH

SYSTEM SWITCH ON THERMOSTAT

IN WRONG POSITION.

RESET THERMOSTAT SYSTEM SWITCH.

MINIMUM-OFF TIMES IN THERMOSTAT

IN OPERATION ON COOLING

WAIT 5 -10 MIN. OR USE SELF-TEST IN THERMOSTAT.

SEE CHECKOUT.

INCORRECT WIRING

CHECK CIRCUIT DIAGRAM.

CONSULT FURNACE OR AIR CONDITIONER

INSTRUCTIONS.

FURNACE OR AIR CONDITIONER

INOPERATIVE

PARTIAL DISPLAY

NO DISPLAY

INOPERATIVE THERMOSTAT

NO POWER TO THERMOSTAT

REPLACE THERMOSTAT.

CHECK THAT HEAT OR COOL SYSTEM POWER IS ON.

THERMOSTAT MOUNTED

INCORRECTLY ON BASE.

SEE INSTALLATION INSTRUCTIONS FOR CORRECT

MOUNTING.

PRESENT SETTING APPEARS

INACCURATE.

•

NORMAL OPERATION THERMOSTAT TURNS ON

HEATING/COOLING EARLY TO MEET TEMPERATURE

SETTING AT PROGRAMMED TIMES.

RECOVERY CAN BE ENDED BY PUSHING WARMER/

COOLER KEYS.

THERMOSTAT IS IN RECOVERY

MODE.

CANNOT TEMPORARILY OVERRIDE

BOTH HEATING AND COOLING

SETTINGS IN AUTO MODE.

PRESS AND HOLD DOWN PRESENT SETTING KEY TO

ALTERNATE BETWEEN HEATING AND COOLING SETTINGS.

NOT USING PRESENT SETTING KEY.

THERMOSTAT TEMPERATURE NEEDS

TO BE ADJUSTED ON A REGULAR

BASIS.

REPROGRAM THERMOSTAT TO MAKE PERMANENT

CHANGE IN PROGRAM. WARMER/COOLER KEYS ARE

TEMPORARY UNLESS PERIOD KEY IS PRESSED FIRST.

WARMER/COOLER KEYS BEING

USED TO ADJUST TEMPERATURE

PROGRAM IS LOST DUE TO POWER

OUTAGE OR DISPLAY GOES BLANK

WHEN POWER IS TURNED OFF.

BATTERIES ARE INCORRECTLY

INSTALLED.

REMOVE AND REPLACE PER MARKINGS ON THERMOSTAT.

REPLACE BATTERIES.

BATTERIES ARE DEAD.

DISPLAY FLASHES WHILE

PROGRAMMING.

CHECK PROGRAMMING INSTRUCTIONS FOR CORRECT

PROGRAM SEQUENCE.

IMPROPER PROGRAM SEQUENCE

AUTOMATIC THERMOSTAT HEATING

OR COOLING TEMPERATURE CAN

NOT BE SET CLOSER THAN 3 F.

SET HEATING AND COOLING TEMPERATURES 3 F OR

MORE APART.

DISPLAY FLASHES DURING

OPERATION.

PROGRAMMING HAS BEEN LOST

BECAUSE OF A POWER OUTAGE.

REPROGRAM ACCORDING PROGRAMMING INSTRUCTIONS

(MAKE SURE BATTERIES ARE INSTALLED).

M5234A

68-0134

T8624C,D

GLOSSARY

Recovery

The time when the thermostat operates the heating or

air conditioning equipment to return the home from the

energy saving temperature to the comfort temperature.

The thermostat starts the recovery period early so the

home will be at the comfort setting by the time the

homeowner has chosen.

Troubleshooting

Glossary

Saturday program schedule

The schedule of WAKE, LEAVE, RETURN and

SLEEP period start times and temperatures programmed

to run on Saturdays.

Comfort temperature

Setback

The temperature desired when active and occupying

the home.

Reducing the temperature in the home for a set period

in heating for energy savings. The lower temperature is

the energy saving temperature.

Energy-saving temperature

The lower (heating) or higher (cooling) temperature

that allows savings on heating and cooling costs when

asleep or away. Also called the setback (heating) or

Setup

Raising the temperature in the home for a set period

in cooling for energy savings. The higher temperature is

the energy saving temperature.

Temperature

Start

Time

Period

WAKE

Heating Cooling

Setpoint

6:00 AM

70° F

78° F

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

LEAVE

RETURN

SLEEP

——— No program ————

(

setpoint) goes into effect.

10:00 PM

60° F

78° F

Sunday program schedule

setup (cooling) temperature.

The schedule of WAKE, LEAVE, RETURN and

SLEEP period start times and temperatures programmed

to run on Sundays.

Period key

One of the four keys—WAKE, LEAVE, RETURN or

SLEEP—to check or program the start time and

temperatue for a time period.

SYSTEM light

This light glows whenever the thermostat is calling

for heating or air conditioning.

Preprogrammed schedule

This is the schedule programmed into the thermostat

at the factory. It sets a night program that provides

energy savings when homeowner sets no program, or if

personal program is lost for any reason. The program,

which is the same for all days of the week, is:

Time period

One of four program periods: WAKE, LEAVE, RE-

TURN and SLEEP available with the thermostat. One

period begins when the previous program period ends:

WAKE—The time period that the house is at a com-

fortable temperature while the family gets up and gets

ready to leave for work or school. This is the only

period that must contain a time and temperature.

LEAVE—The time period that the temperature can

be set back (winter) or set up (summer) for energy

Program

The times and temperatures homeowner sets to define

the comfort and energy saving periods for each day

schedule.

home.

RETURN—The time period that the house is at a comfortable st ea mv i pn eg rsa t bu er ec af ou rs ef a mt h ie lyfa cmt ii vl yi ti ei ss i un s tuh ae l leyv e an wi na gy b fe rf oo mr e

bedtime.

SLEEP—The time period that the temperature can be set back (winter) or set up (summer) for energy savings

because the family is sleeping. It can be set to start at the family’s normal bedtime. Often the SLEEP program is set

only for the heating season so family members can sleep cool in the cooling season.

Weekday program schedule

The schedule of WAKE, LEAVE, RETURN and SLEEP period start times and temperatures programmed to run

Monday through Friday.