68-0162 - t8501 and t8511 deluxe electronic thermostats · t8501 and t8511 deluxe electronic...

PRODUCT DATA

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

T8501 and T8511Deluxe Electronic Thermostats

APPLICATIONThe T8501 and T8511 Deluxe Electronic Thermostats provideelectronic control of 18 to 30 Vac single stage or multistageheating and cooling systems, including heat pump systems.

T8501/T8511FEATURES AND BENEFITS• Attractive styling complements any decor to the

homeowner’s delight.• Ease-of-use means fewer homeowner questions and

increased homeowner satisfaction.• Back lighting the large display makes the Liquid

Crystal Display (LCD) very easy to read.• Most frequently used keys are located by the LCD for

quick and easy access to information.• Models available with outdoor temperature sensor

capability for homeowner convenience. The sensor isalso more accurate than a thermometer.

• Configurable features allows one model to be used toreplace many different models (less inventory, noneed 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 heatpumps protects and extends the life of the equipment.

• Easy installation, setup and system test savesinstaller time and increases productivity.

• System test simplifies troubleshooting and saves timeby overriding the time delays.

• Setpoints are permanently held in memory (nobatteries used) and retained during power outages forincreased installer and homeowner convenience.

Contents

Application........................................................................... 1T8501/T8511 Features and Benefits ................................... 1Specifications ...................................................................... 2Ordering Information ........................................................... 2Installation ........................................................................... 3Wiring .................................................................................. 4Settings ............................................................................... 6Installer Setup ..................................................................... 6Installer System Test ........................................................... 8Checkout ............................................................................. 10Operation ............................................................................ 11Wiring Diagrams (Fig. 13-18) .............................................. 12Troubleshooting Guide ........................................................ 14

68-0162-1

T8501 AND T8511 DELUXE ELECTRONIC THERMOSTATS

68-0162—1 2

ORDERING INFORMATION

When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to theTRADELINE® Catalog or price sheets for complete ordering number.

If you have additional questions, need further information, or would like to comment on our products or services, please write orphone:1. Your local Home and Building Control Sales Office (check white pages of your phone directory).2. Home and Building Control Customer Relations

Honeywell, 1885 Douglas Drive NorthMinneapolis, Minnesota 55422-4386

In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9.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.

SPECIFICATIONSIMPORTANT

The specifications given in this publication do notinclude normal manufacturing tolerances; therefore,an individual unit may not exactly match the listedspecifications. Also, This product is tested andcalibrated under closely controlled conditions, andsome minor differences in performance can beexpected if those conditions are changed.

Models:See Table 1.

Electrical Rating:Input Power: 18 to 30 Vac, 50/60 Hz.Load Rating: See Table 2.

Temperature:Setpoint Range: 40°F to 99°F (4°C to 37°C) depending on

model and if in heating or cooling.Display Range:

Controlled: 30°F to 110°F (1°C to 43°C).Outdoor: -30°F to 120°F (-34°C to 49°C).

Display Updates:Controlled: updated every minute.Outdoor: displayed on demand and updated every10 minutes.

Differential (auto changeover models):3°F (1.5°C) minimum.

Interstage Differential:1.7°F (0.9°C) heat pump models.

Minimum Off Time (Cooling and Heat Pumps):5 minutes ± 0.5.

Table 1. T8501 and T8511 models.

Table 2. Maximum Amps at 18 to 30 Vac.

Relay Running (A) Inrush (A)

Heat .02 to 1.5 3.5 at 200,000 cycles

Cool .02 to 1.5 7.5 at 100,000 cycles

Fan, Reversing Valve, Emergency Heat .02 to 0.5 2.5 at 200,000 cycles

Model System Changeover System SelectionFan

Selection Comments

T8501D Heat-Cool Automatic/Manual Selectable

Heat-Off-Cool-Auto On-Auto System and fan selections aredone by keyboard.

T8511G Heat pump Automatic/Manual Selectable

Em. Heat-Heat-Off-Auto-Cool On-Auto System and fan selections aredone by keyboard.


68-0162—13

Operating Ambient Temperature:40°F to 110°F (4°C to 43°C).

Shipping Temperature Range:Minus 20°F or 130°F (-29°C to 54°C).

Operating Relative Humidity Range:5% RH to 90% RH; noncondensing.

Mounting:The thermostat mounts on a wallplate. The wallplate mountshorizontally on a wall or 2 in. x 4 in. outlet box with the screwsprovided. Leveling is not required.

Dimensions:See Fig. 1.

5-1/4 (133) 1/2(13)

1-9/16(40)

4-1/8(105)

3-13/16(97)

1-13/16(46)

3/8 (10)

2-3/4 (70)

3-5/8 (92)

M11306

Fig. 1. Thermostat dimensions in in. (mm).

RECYCLING NOTICEIf this control is replacing a control that containsmercury in a sealed tube, do not place your oldcontrol in the trash.

Contact your local waste management authority forinstructions regarding recycling and the properdisposal of the old thermostat.

INSTALLATION

When Installing this Product...1. Read these instructions carefully. Failure to follow the

instructions can damage the product or cause ahazardous condition.

2. Check the ratings given in the instructions and on theproduct to make sure the product is suitable for yourapplication.

3. Installer must be a trained, experienced servicetechnician.

4. After completing installation, use these instructions tocheckout the product operation.

CAUTIONDisconnect power supply to prevent electrical shockor equipment damage.

LocationInstall the thermostat about 5 ft. (1.5m) above the floor in anarea with good air circulation at average temperature. SeeFig. 2.

Do not install the thermostat where it can be affected by:— drafts, or dead spots behind doors and in corners.— 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.

Wallplate InstallationThe thermostat can be mounted horizontally on the wall or a2 in. x 4 in. wiring box. Position wallplate horizontally on thewall 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 notlevel.

2. Use a pencil to mark the mounting holes. See Fig. 3.


68-0162—1 4

5 FEET[1.5 METERS]

YES

NO

NO

NO

M10106

3. Remove the wallplate from the wall and drill two 3/16inch holes in the wall (if drywall) as marked. For firmermaterial such as plaster or wood, drill two 7/32 inchholes. Gently tap anchors (provided) into the drilledholes until flush with the wall

Table 3. Terminal Designations and Descriptions.

StandardTerminal

Designations

AlternateTerminal

Designations Typical Connection Function Terminal Type

B — Heating changeover valve or damper Output 24V powered contact

C B, X, X1, X2 Common Input

E K Emergency heat relay Output 24V powered contact

G F Fan relay Output 24V powered contact

O R Cooling changeover valve Output 24V powered contact

O/B — Cooling/heating changeover valve or damper Output 24V powered contact

OT, OT — Outdoor temperature sensor input for C7089B Input —

R V 24V system transformer Input —

RC — 24V cooling transformer Input —

RH V 24V heating transformer Input —

W — Heating relay Output 24V powered contact

W1 H1, R3 Heating relay Output 24V powered contact

W2 H2, R4, W3, Y Stage 2 heating relay or auxiliary heat relay Output 24V powered contact

X1 A1, A, C, L, X, Z User defined Light Emitting Diodes (LEDs) Annunciation —

Y, Y1 C1, M, Y Compressor contactor Output 24V powered contact

L A, A1, X, Z User defined Light Emitting Diodes (LEDs) Annunciation —

4. Position the wallplate over the holes, pulling wiresthrough the wiring opening.

5. Loosely insert the mounting screws into the holes.6. Tighten mounting screws.

WIRINGAll wiring must comply with local electrical codes andordinances. Follow equipment manufacturer wiringinstructions when available. Refer to Fig. 13 through 17 fortypical hookups. A letter code is located near each terminalfor identification. Refer to Table 3 for terminal designations.

Fig. 2. Typical location of thermostat.


68-0162—15

CAUTIONDisconnect power before wiring to prevent electricalshock or equipment damage.

1. Loosen the terminal screws on the back of thethermostat and connect the system wires. See Fig. 4.

IMPORTANTUse 18 gauge, color-coded thermostat cable forproper wiring.

2. Securely tighten each terminal screw.3. Push excess wire back into the hole.

WIRES THROUGH WALL

WALL

MOUNTING HOLES

MOUNTING SCREWS

M6530

WALLANCHORS(2)

M4826

FOR WRAPAROUNDINSERTION STRIP7/16 IN. (11 MM).

FOR STRAIGHTINSERTION STRIP5/16 IN. (8 MM).

Fig. 3. Mounting the wallplate.

4. Plug the hole with nonflammable insulation to preventdrafts from affecting the thermostat.

Fig. 4. Proper wiring technique.

Mounting Thermostat1. Engage tabs at the top of thermostat and wallplate.

See Fig. 5.2. Press lower edge of case to latch.

NOTE: To remove the thermostat from the wall, first pull outat the bottom of the thermostat; remove top last.

M6798A

B. PRESS LOWER EDGE OF CASE TO LATCH.

A. ENGAGE TABS AT TOP OF THERMOSTAT AND WALLPLATE.

Fig. 5. Mounting thermostat on wallplate.

Using Thermostat KeysThe thermostat keys are used to:• set temperature,• display present setting,• configure Installer Setup,• check System Test,• display outdoor temperature (select models).

Select models have keys to:• set the system operation,• set the fan operation.

See Fig. 6 for the location of the keys.

Fig. 6. Thermostat key location and description.M6801

DISPLAY PRESENT SETTINGS AND SCROLL THROUGH INSTALLER SETUP (INFORMATION KEY)

i DECREASETEMPERATURE SETTING

INCREASETEMPERATURE SETTING


68-0162—1 6

SETTINGS

System and Fan SettingsSystem settings control the thermostat operation as follows:

Em. Heat (T8511 only): Emergency heat relay isautomatically controlled by the thermostat. The coolingsystem is off. The compressor is de-energized.

Heat: The thermostat controls the heating.Off: Both the heating and cooling are off.Cool: The thermostat controls the cooling.Auto: The thermostat automatically changes between

heating and cooling operation, depending on the indoortemperature.

Fan settings control the system fan as follows:On: Fan operates continuously.Auto: Fan operates with equipment.

The system default setting is Heat and the fan default settingis Auto. Use the keyboard to change to the desired settings.See Fig. 7 and 8.

M10147

i

Press to selectheating or coolingequipment.

Em. Ht.-Emergency heatingHeat— Heating equipmentOff — No equipmentCool—Cooling equipmentAuto—Thermostat

automatically selectsheating and coolingequipment.

Press to selectheating or coolingequipment.

On— Fan runs continuouslyAuto—Fan runs when

heating or coolingequipment operates

System

System

SystemFan

Fan

Fan

1

1 CHECK LIGHT ON SELECT MODELS

Fig. 7. Thermostat System and fan key location.

NOTE: Always press the keys with your fingertip or similarblunt tool. Sharp instruments like a pen or pencilpoint can damage the keyboard.

Temperature SettingsThe default setpoint for heat is 70°F (21°C) and for cool is78°F (25.5°C). Press the increase ▲ or decrease ▼ key tochange the present setting. To change between heat andcool, press the Information i key until the setting to bechanged appears. Press the increase ▲ or decrease ▼ keyto adjust the setting.

INSTALLER SETUPNOTE: For most applications, the thermostat factory

settings will not need to be changed. Review thefactory settings in Table 4 and if no changes arenecessary, go to the Installer System Test section.

The Installer Setup is used to customize the thermostat tospecific systems. Installer Setup numbers are listed inTable 4. The table includes all the configuration optionsavailable.

A combination of key presses are required to use the InstallerSetup 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 displaysegments appear for approximately three seconds beforethe number is displayed. See Fig. 8 and 9.

— To advance to the next Installer Setup, press theInformation i key.

— To change a setting, use the increase ▲ and decrease ▼keys.

— To exit the Installer Setup, press and hold the Information i key until the display returns to normal (approximatelythree seconds). The display will scroll the numbersbackwards to get to the normal display. The InstallerSetup is automatically exited if no key presses are madefor five minutes.

Em HeatOffCool Auto Only

Heat Cool

OnAutoSystem Fan

Room

Outdoor

Em Ht Temporary Setting

Wait

%HumidAux Ht

Remote

ReplBatt

M4844

Fig. 8. All the segments of LCD displayed.

Fig. 9. Installer Setup and setting displayed.

CAUTIONHeat pump and electric heat systems must beconfigured to 01 in Installer Setup 02 to preventequipment damage caused by the system runningwithout the fan (T8501 only).

IMPORTANTOnly configurable numbers are shown on the device.Example: If thermostat does not have a system key,Installer Setup number 12 will not be displayed.Review Table 4 factory settings and mark any desiredchanged in the Actual Setting column. When theInstaller Setup is complete, review the settings toconfirm that they match the system.

M10406

INSTALLER SETUPNUMBER DISPLAY (COLUMN 2 OF TABLE 4)

FACTORY SETTING OROTHER CHOICE DISPLAY(COLUMN 3 OR 5 OF TABLE 4)


68-0162—17

Table 4. Thermostat Installer Setup Options.

(continued)

Installer SetupNumber

(Press i key Factory-SettingOther Choices

(Press ▲ or ▼ key to change) ActualSelect to change) Display Description Display Description Setting

Not used 01 — — — — —

Fan operationa, b 02 00 Conventional applica-tions where equipmentcontrols fan operationin heat mode

01 Heat pump and electric heatapplications where thermostatcontrols fan operation in heatmode

Not used 03 — — — — —

Heating cycle rate 04b Depends Stage one 01, 03, 06 01—1 cph used for radiant floor

05b on model Stage two or 09 heat, gravity systems

06 — Not used 03—3 cph used for hot water

07b 09 Emergency heat systems or high efficiency

furnaces

06—6 cph used for conventionalsystems

—

09—9 cph used for electric heatsystems

Not used 08 thru 11 — — — — —

Changeover 12 01 Manual changeover 00 Automatic changeover

Not used 13 — — — — —

Degree tempera-ture display

14 00 Temperature isdisplayed in °F

01 Temperature is displayed in °C

Not used 15 thru 18 — — — — —

Extended fanoperation inheatinga,b

19 00 No extended fanoperation after the callfor heat ends

01 Fan operation is extended 90 seconds after the call for heat ends

Extended fanoperation incoolingb

20 00 No extended fanoperation after the callfor cool ends

01 Fan operation is extended 90 seconds after the call for cool ends

Not used 21 thru 23 — — — — —

Outdoortemperaturedisplayb

24 00 No outdoor tempera-ture is displayed

01 Outdoor temperature isdisplayed. Needs a C7089B1000Outdoor Sensor to operate.

Not used 25 thru 28 — — — — —

O/B terminal ener-gized in heating orcoolingb

29 00 O/B terminal isenergized for reversingvalve in cooling

01 O/B terminal is energized forreversing valve in heating

Not used 30 thru 32 — — — — —

Minimum off timefor thecompressor

33 05 5 minute minimum offtime for thecompressor

00, 01, 02,03 or 04

Minimum number of minutes (0 thru 5) the compressor will beoff between calls for thecompressor

Heating setpointrange stop

34 90 Heating setpoint canbe set no higher than90°F

40 thru 90 Number can be set anywherebetween 40 and 90 in 1°Fincrements

Cooling setpointrange stop

35 48 Cooling setpoint canbe set no lower than48°F

48 thru 99 Number can be set anywherebetween 48 and 99 in 1°Fincrements


68-0162—1 8

Table 4. Thermostat Installer Setup Options (continued).

IMPORTANTReview the settings to confirm that they match thesystem.

INSTALLER SYSTEM TESTUse the Installer System Test to check the thermostatconfigurations and operation. Refer to Table 5 for a list of theavailable system tests.

To start the system test:

NOTE: The minimum off time for compressors is bypassedduring the Installer System Test.

Fig. 10. All the segments of the LCD displayed.

Em HeatOffCool Auto Only

Heat Cool

OnAutoSystem Fan

Room

Outdoor

Em Ht Temporary Setting

Wait

%HumidAux Ht

Remote

ReplBatt

M4844

Fig. 11. Test number displayed.

Refer to Table 6 for the directions and results of thespecific tests.

NOTE: Press and hold the increase ▲ and decrease ▼keys together for three seconds to exit the systemtest. The system test will time out after five minuteswithout any key presses.

Press and hold the increase ▲ and decrease ▼ keys at thesame time until two zeros appear. All segments of the displaywill be displayed before the two zeros appear. See Fig. 10and 11.

M6792ATEST NUMBER

Installer SetupNumber

(Press i key Factory-SettingOther Choices

(Press ▲ or ▼ key to change) ActualSelect to change) Display Description Display Description Setting

Not used 36 — — — — —

Temperaturedisplayadjustment

37 00 No difference indisplayed temperatureand actual roomtemperature

+3 thru -3 1—Display adjusts to 1°F higherthan actual room temperature

2—Display adjusts to 2°F higherthan actual room temperature

3—Display adjusts to 3°F higherthan actual room temperature

-1—Display adjusts to 1°F lowerthan actual room temperature



a Number 02 must be set to 01 to extend fan operation on T8501.b Available on select models.


68-0162—19

Table 5. Tests Available in the Installer System Test.

Table 6. Installer System Test Options.

Key toPress

TestNumber Description

Heating Equipment System Test

i 10 Enter heating equipment system test.

▲ 11 Stage-one heat comes on. When Installer Setup number 02 is 01, the system fan is also energized.

▲ 12a Stage-two heat comes on. Stage-one heat and system fan remain on.

▼ 11a Stage-two heat turns off.

▼ 10 Stage-one heat and system fan turn off.

Emergency Heating Equipment System Test (T8511 models only)

i 20 Change from heating to emergency heating equipment system test.

▲ 21 Emergency heat comes on. System fan also comes on.

▼ 20 Emergency heat turns off.

Cooling Equipment System Test

i 30 Change from heating or emergency heating to cooling equipment system test.

▲ 31 Cooling and system fan come on.

▼ 30 Cooling and system fan turn off.

Fan Equipment System Test

i 40 Change from cooling to fan equipment system test.

▲ 41 Fan comes on.

▼ 40 Fan turns off.

Key or Switch Operation System Test IMPORTANT

Test numbers will only be displayed when the system is configured for the selected function. EXAMPLE: Numbers 60, 61 and 62 are the only numbers that will be displayed when a system is configured for heat only.

SYSTEM KEY SYSTEM TEST

i 60 Change from cooling or fan to key operation system test.

System 61 Heat test number is displayed.

System 62 Off test number is displayed.

System 63 Cool test number is displayed.

System 64 Auto test number is displayed.

Systema 65 Emergency heat test number is displayed.NOTE: Press system key again to repeat the System Key System Test.

FAN KEY SYSTEM TEST

Fan 68 Fan on test number is displayed.

Fan 69 Fan off test number is displayed.a Available on select models.

Test Number System Test Description

10-19 Heating equipment can be turned on and off

20-29 Emergency heat (select models) equipment can be turned on and off

30-39 Cooling equipment can be turned on and off

40-49 Fan equipment can be turned on and off.

60-69 System key

70-79 Thermostat information including date code and software versions are displayed


68-0162—1 10

Thermostat Information1. Press the Information i key to access the thermostat

information.

M4864

2. Press the increase ▲ key to display the production datecode. The first two large digits are the month and thethird digit is the last digit of the year(Example: 026=February 1996).

M4865

3. Press the increase ▲ key again to display the softwareidentification code. (Example: 02 = software ID code 2).

M4866

4. Press the increase ▲ key again to display the softwarerevision number (Example: 001=Revision number 1).

M4867

M6791

5. Press the increase ▲ key again to display the EEPROMidentification code.(Example: 222 = EEPROM ID 222).

6. Press and hold the increase ▲ and decrease ▼ keystogether, until the room temperature is displayed, to exitthe system test. The system test times out after fiveminutes without any key presses.

CHECKOUT

Outdoor Temperature Sensor(where applicable)Allow the outdoor temperature sensor to soak in the outdoorair for a minimum of five minutes before taking a reading.

With an accurate thermometer (±1°F [±0.5°C]), measure thetemperature at the sensor location, allowing time for thethermometer to stabilize before reading. Match thethermometer reading to the outdoor temperature display atthe thermostat.

To verify the resistance of the sensor, remove one wire fromone of the OT terminals. Use an ohmmeter to measure theresistance across the sensor. Then verify sensor accuracywith the temperature/resistance curve of Fig. 12.

Fig. 12. Sensor resistance vs. temperature performancecharacteristics.

0

100

200

300

400

500

600

700

800

900

RE

SIS

TA

NC

E (

K o

hm)

-40(-40)

-20(-29)

0(-18)

20(-7)

40(4)

60(16)

80(27)

100(38)

120(49)

°F(°C)

OUTDOOR TEMPERATUREM10172A


68-0162—111

OPERATION

Thermal PerformanceDuring severe weather, the thermostat actually controls closerto the setpoint than a conventional control. This is becausethe heat anticipator is replaced by two electronic controlstrategies—cycling by heat anticipation and proportional plusintegral control.

Electronic cycling by heat anticipation acts like a traditionalheat anticipator except that it never needs adjusting forvarious control circuit load currents. It cycles the heatingsystem off slightly before the room temperature reaches thesetpoint to keep the heat left in the ductwork from overheatingthe room.

In severe weather, a conventional control with a heatanticipator tends to turn off the system too soon so theeffective setpoint is somewhat below the setpoint. In very coldweather, the difference between setpoint and effective controlpoint can be 5°F or 6°F (2°C or 3°C) with a conventionalcontrol. This phenomenon is called droop.

Proportional plus integral action eliminates droop by adjustingthe on time of the stage that is cycling longer or shorter untilthe control point matches the setpoint. The thermostatmaintains the space temperature within 1°F of the setpoint.

The zero droop performance provides improved occupantcomfort and energy savings. Occupants do not need tocontinually adjust thermostat settings to maintain desiredtemperature, even during severe weather.

Operation SequenceThe thermostat energizes specific terminals depending whatthe Fan and System are set to. The LCD will display symbolsand words to report the condition of system. See Tables 7 and8 for specific information.

Table 7. T8501 Sequence of Operation.

FanSelection

SystemSelection Call Energize Displaya

Auto Off None None None

On Off None G

Auto Cool None Ob None

Auto Cool or Auto Cooling Ob, G, Y and

Auto Heat None Bb None

Auto Heat or Auto Heating Bb, Wc

Auto Auto None O or Bd Nonea System selection is displayed. b Only available on select models.c When electric heat fan is selected, G is energized and fan

symbol is displayed.d Based on last piece of equipment called (cooling = O or

heating = B) and Installer Setup selection.

Table 8. T8511 Sequence of Operation for Separate Compressor Terminal (Y and W1) Models.

Fan Selection System Selection Call Energize Displaya

Auto Off None None None

Auto Off Fan G

On Off None G

Auto Cool None O None

Auto Cool or Auto Cooling O, G, Y and

Auto Heat None B None

Auto Heat or Auto Heating B, W1 and

Auto Heat or Auto Heating B, W1, W2, , and Aux Ht

Auto Em Heat None B Em Ht

Auto Em Heat Stage 1 heating B, E , and Em Ht

Auto Em Heat Stage 2 heating B, E, W2 , , Em Ht and Aux Ht

Auto Auto None O or Bb Nonea System selection is displayed. b Based on last piece of equipment called (cooling = O or heating = B)

and Installer Setup selection.


68-0162—1 12

Minimum-Off TimingA minimum-off timer assures that the cooling compressor orheat pump compressor does not come on again for at leastfive minutes after it turns off. The minimum-off timer istriggered when the compressor goes off and when the systemswitch is changed. If he compressor turns off when thesetpoint is changed, then the minimum-off timer is triggered.The minimum-off timer operates during the first stage of bothheating and cooling on the heat pump thermostat models andcooling only on the standard application models.

Emergency Heat (select models)When the system is set for Emergency Heat, the auxiliary orEmergency heat is stage one and the compressor stages arelocked off. Depending on the model, the fan may be activatedwhen Emergency Heat is used.

Fan ControlThe fan will be on when any of these conditions are present(it can take up to 20 seconds for the fan to turn on).

Fan On: This setting means that the fan is energizedcontinuously.

Fan Auto: The Auto setting means the fan will run onlywith the heating and cooling system.

Select models allow the installer the option of electric orconventional heat fan operation in the installer setup. Whenset for electric heat systems, the fan comes on at the sametime as the heat and is energized by the thermostat. The fanis energized by the plenum switch when set for conventionalheating system.

Outdoor Temperature Sensor (select models)The outdoor temperature sensor is used to display theoutdoor temperature. Pressing the Information i key oncewill show the outdoor temperature if Installer Setup number24 is set to 02.

WIRING DIAGRAMS (Fig. 13-17)

L1(HOT)

L2

POWER SUPPLY. PROVIDE DISCONNECT MEANS ANDOVERLOAD PROTECTION AS REQUIRED.

AVAILABLE ON SELECT MODELS.

1

HEATINGRELAY ORVALVE COIL

M4821

COMPRESSORCONTACTOR

FANRELAY

ROT OT C B O G Y W

OUTDOORTEMPERATURESENSOR

COOLCHANGEOVERVALVE OR DAMPER

HEATCHANGEOVERVALVE OR DAMPER

THERMOSTAT

1

2

2

Fig. 13. Typical hookup in heat only standard application.

Fig. 14. Typical hookup in one transformer heat and coolstandard application.

Fig. 15. Typical hookup in heat pump application.

L1(HOT)

L2



1

HEATINGRELAY ORVALVE COIL

M15089

ROT OT C W


THERMOSTAT

1

2

2

FANRELAY

G

L1(HOT)

L2



1

M15091

COMPRESSORCONTACTOR

FANRELAY

ROT OT O G Y C L W1


COOLCHANGEOVERVALVE

THERMOSTAT

1

2

2

B

HEATCHANGEOVERVALVE

EQUIPMENT

MONITOR


68-0162—113

Fig. 16. Typical hookup in heat pump system withemergency heat relay.

L1(HOT)

L2



1

HEATRELAY 2

M4830

COMPRESSORCONTACTOR

FANRELAY

ROT OT O/B G Y1 C E W2


COOL/HEATCHANGEOVERVALVE

EM. HEATRELAY

THERMOSTAT

1

2

2

W1 X1

HEATRELAY 1

EQUIPMENT

MONITOR

Fig. 17. Typical hookup in heat pump application withemergency heat relay and O/B terminal.

TROUBLESHOOTING GUIDE

(continued)

Symptom Possible Cause Action

Display will not come on. Thermostat is not beingpowered.

• Check that C terminal is connected to the system transformer.• Check for 24 Vac between C and R or RH terminals.— 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 the power switch on the HVAC equipment is in the Off

position—set to the On position.— check wiring between thermostat and HVAC equipment—

replace any broken wires and tighten any loose connections.— If 24 Vac is present, proceed with troubleshooting.

Temperature display isincorrect.

Room temperaturedisplay has beenreconfigured.

Enter Installer Setup number 37 and reconfigure the display.

Thermostat isconfigured for °F or °Cdisplay (select models).

Enter Installer Setup number 14 and reconfigure the display.

Bad thermostat location. Relocate the thermostat.

Temperature settings willnot change. (Example:Cannot set the heatinghigher or the cooling lower.)

The upper or lowertemperature limits werereached.

Check the temperature setpoints:• T8511 heating limits are 40°F to 90°F (7°C to 31°C) and T8501

heating limits are 45°F to 88°F• Cooling limits are 48°F to 99°F (9°C to 37°C).

The setpointtemperature rangestops were configured.

Check Installer Setup numbers 34 and 35 and reconfigure the setpointstops.

L1(HOT)

L2



1

AUX. HEATRELAY

M15092

COMPRESSORCONTACTOR

FANRELAY

ROT OT O G Y C E L


COOLCHANGEOVERVALVE

EM. HEATRELAY

THERMOSTAT

1

2

2

W2

EQUIPMENT

MONITOR

W1


68-0162—1 14

Symptom Possible Cause Action

Heating will not come on. No power to thethermostat.

• Check that C terminal is connected to the system transformer.• Check for 24 Vac between C and R or RH terminals.— 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 the system switch at the equipment is in the Off

position—set to On position.— check wiring between thermostat and HVAC equipment—


Thermostat minimum offtime is activated.

Wait up to five minutes for the system to respond.

System selection is notset to Heat.

Set system selection to Heat.

O/B terminal configuredincorrectly (selectmodels).

Check Installer Setup number 29 and reconfigure correctly.

O or B terminalmiswired (selectmodels).

Check system description to determine whether changeover should beenergized in heat (B) or cool (O). Rewire if necessary.

Cooling will not come on. No power to thethermostat.

• Check that C terminal is connected to the system transformer.• Check for 24 Vac between C and R or RC and Y terminals.— 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 the system switch at the equipment is in the Off

position—set to the On position.— check wiring between thermostat and HVAC equipment—


Thermostat minimum offtime is activated.

• Wait up to five minutes for the system to respond.• Enter Installer Setup mode number 33. Reconfigure minimum off

time (if required).

System selection is notset to Cool.

Set system selection to Cool.

O/B terminal configuredincorrectly (selectmodels).

Check Installer Setup number 29 and reconfigure correctly.

O or B terminalmiswired (selectmodels).

Check system description to determine whether changeover should beenergized in heat (B) or cool (O). Rewire if necessary.

System On indicator is lit,but no heat is beingdelivered.

Heating equipment isnot operating.

Verify operation of heating equipment in system test.

Outdoor temperature not displayed (selectmodels)

Option not activated. Enter Installer Setup number 24 and set to 01. Thermostat must haveOT terminals and a C7089B1000 installed.

Outdoor temperature display is incorrect (select

Outdoor sensor isconnected incorrectly.

Refer to C7089B1000 installation instructions and check wiringbetween the thermostat and sensor.

models) Wrong sensor. Replace sensor with C7089B1000 sensor.

TROUBLESHOOTING GUIDE (continued)


68-0162—115


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