Honeywell T8090A Thermostat User Manual

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TRADELINE

T8090A Heating, Cooling,

and Heating-Cooling Thermostat,

Wallplate and Subbase

Assure power is off to the heating, cooling, or heating/

cooling system at the main fuse panel. Most buildings have

a separate switch box or circuit breaker for disconnecting

power to the heating and cooling (if applicable) equipment.

This thermostat is compatible with all heating, cooling or

heating/cooling systems when thermostat is powered by

batteries. If thermostat is not powered by batteries, refer to

Table1forthermostatandsystemcompatibilityinformation.

Preparation

Check thermostat and subbase (if used) suitability for

the heating, cooling, or heating/cooling system. Refer to

Table 1.

Assemble tools required: flat bladed screwdriver, hand

or power drill with 3/16 in. drill bit, wire cutter/stripper or

sharp knife, bubble level or plumb bob and line.

TABLE 1—SYSTEM COMPATIBILITY FOR NON-BATTERY POWERED THERMOSTATS.

Type of Heating System to be Controlled

Conditions/Compatibility

Electric (Line Voltage)—Typical baseboard and

radiant

•

The R8239D1015 Isolating Relay or R841 Silent

Switching Center must be installed in the thermostat

control circuit.a,b

Fan Coil Unit

•

Compatible. Assure correct subbase identity selected for

fan control.

Gas—Direct Spark Ignition (DSI), Intermittent

Pilot (IP), and Standing Pilot (SP)

Compatible. If not using battery backup, assure that the

24V control transformer common is accessible for

connection to thermostat cable conductor and power to

the transformer is not regularly interrupted by high

temperature or limit operation.

Heat Pump

•

Compatible. Assure correct subbase identity is selected

for fan control and changeover control (O terminal for

cool and B terminal for heat).

Hot Water Zone

•

Honeywell 2-wire valves are compatible.

Some non-Honeywell 2-wire valves will require an

R8239D1015 Isolating Relay in the thermostat control

circuit.a,b

•

Some 3-wire valves will require an R8239A1052

Isolating Relay in the thermostat control circuit.a,c,b

Oil

If not using battery backup, assure that the 24V control

transformer common is accessible for connection to

thermostat cable conductor and power to the transformer

is not regularly interrupted by high temperature, purge

cycle, or limit operation.

Vent Damper

•

Honeywell damper motors are compatible.

Some non-Honeywell damper motors will require an

R8239D1015 Isolating Relay in the thermostat control

circuit. Check control amperage requirement.

Warm Air Zone

•

Most are compatible.

If thermostat is not compatible with the system being controlled, the system will not operate. No hazard exists. The thermostat

will not be damaged unless it is used to directly control a line voltage system. For proper system operation, a Honeywell R841

or R8239D1015 Isolating Relay must be added to the thermostat control circuit.

Cut the two black heat anticipator jumper wires before installing the thermostat. See Set Heat Anticipator section.

Consult manufacturer for installation requirements.

D.F. • Rev. 10-94 •

•

©Honeywell Inc. 1994 • Form Number66 99 - -00 77 55 00 —— 11

M3375

UNPACK THERMOSTAT

Handle your new thermostat carefully; rough handling

may interfere with its accuracy. Before unpacking, refer to

Fig. 1.

M3375 Recycling Notice

This control contains mercury in a sealed tube. Do not

place control in the trash at the end of its useful life.

If this control is replacing a control that contains mer-

cury in a sealed tube, do not place your old control in the

trash.

Remove and discard the shipping wrap.

IMPORTANT: Save package of screws and instructions

for the homeowner.

Contact your local waste management authority for

instructions regarding recycling and the proper disposal of

this control, or of an old control containing mercury in a

sealed tube.

Fig. 1—Unpack thermostat.

THERMOSTAT

COVER

If you have questions, call Honeywell Inc. at 1-800-

68-1502.

Installation

WHEN INSTALLING THIS PRODUCT…

. Read these instructions carefully. Failure to follow

LIFT

COVER

them could damage the product or cause a hazardous

condition.

CAPTIVE

MOUNTING

SCREWS

. Check the ratings given in the instructions and on

the product to make sure the product is suitable for your

application.

THERMOSTAT

BASE

M1518

. Installer must be a trained experienced service

technician.

4. After installation is complete, check out product op-

eration as provided in these instructions.

Remove the thermostat cover by lifting from the bottom.

Set aside cover until needed later.

Carefully remove the material protecting the mercury

switch bulb.

Loosen two captive mounting screws and separate the

wallplate (if provided) from the back of the thermostat base.

CAUTION

. Disconnect power supply to prevent electrical

shock or equipment damage.

. Run wires as close as possible to the subbase.

To prevent interference with the thermostat

linkage, keep wire length to a minimum. Push

excess wire back into the hole and plug hole

to prevent drafts from affecting thermostat

operation.

MOUNT WALLPLATE OR SUBBASE

Wall Mounting (See Fig. 2)

Hold the wallplate or subbase in position on the wall.

See Fig. 2.

Mark holes on the wall for anchors. Use the spirit level

to make sure the wallplate or subbase is level.

Drill 3/16 in. holes and gently tap the anchors into the

holes until flush with the wall.

Pull wires through the large wiring hole in the wallplate

or subbase.

. Do not overtighten thermostat captive

mounting screws because damage to subbase

threads may result.

4. Do not short across coil terminals on relay;

this may burn out the heat anticipator.

Loosely fasten the wallplate or subbase to the wall with

the three screws. Do not tighten the screws completely.

Carefully level the wallplate or subbase and firmly

tighten the screws. See Fig. 3.

LOCATION

Locate thermostat about 5 ft [1.5m] above the floor in an

area with good air circulation at average temperature. Do

not mount the thermostat where it may be affected by:

Outlet Box Mounting (See Fig. 4)

—

drafts, or dead spots behind doors and in corners.

hot or cold air from ducts.

radiant heat from the sun or appliances.

concealed pipes and chimneys.

unheated (uncooled) areas behind the thermostat.

Use a horizontally mounted outlet box if possible. If a

vertical outlet box is used, mount the wallplate or subbase

on a 193121A (beige) or 202689A (white) Cover Plate

Assembly (ordered separately). Follow the instructions

provided with the cover plate assembly.

Align wallplate or subbase mounting holes on the outlet

box and loosely fasten with two screws.

Run wires from the heating, cooling or heating-cooling

equipment to the new thermostat location.

The number of wires required to connect this thermostat

to the heating, cooling or heating-cooling equipment de-

pends on how the thermostat is powered—by the 24 Vac or

battery, or through the control system. Refer to the Typical

Wiring Diagrams section to determine the number of wires

required for your application.

Carefully level the wallplate or subbase and firmly

tighten the screws. See Fig. 3.

9-0750—1

Fig. 2—Mounting wallplate or subbase to wall.

SCREW HOLES

WITH PLASTIC

ANCHORS

SCREW HOLES

WITH PLASTIC

ANCHORS

HEATING-ONLY

WALLPLATE

FAN

OFF COOL

AUTO

HEAT

HEATING/COOLING SUBBASE

M857

M1552A

Fig. 3—Leveling methods

for wallplate or subbase.

SPIRIT LEVEL

PLUMB

LINE

PLUMB

BOB OR

WEIGHT

FAN

OFF COOL

AUTO

HEAT

M1555

Fig. 4—Mounting wallplate or subbase on horizontal outlet box.

EXISTING

HORIZONTAL

OUTLET BOX

EXISTING

HORIZONTAL

OUTLET BOX

HEATING/

COOLING

SUBBASE

HEATING-ONLY

WALLPLATE

FAN

OFF COOL

AUTO

HEAT

M856A

M1553A

VERTICAL

OUTLET

BOX

COVER

PLATE

ADAPTER

RING

SUBBASE OR

WALLPLATE

MOUNTING

SCREWS (2)

NOT INCLUDED WITH UNIT.

M1554A

ACCESSORY PARTS AVAILABLE.

69-0750—1

WIRING

Follow the instructions provided by the heating, cooling

Fig. 6—Thermostat mounting.

or heating-cooling equipment manufacturer. If not avail-

able, refer to the Typical Wiring Diagrams section.

Disconnect power supply before making wiring connec-

tions to prevent electrical shock or equipment damage.

TAB (2)

NOTE: All wiring must comply with local electrical codes

and ordinances.

MOUNTING SLOT (2)

This thermostat clock can be powered by 24 Vac trans-

former with battery backup, 24 Vac transformer only or

battery only, or through the control system. Refer to Figs.

16 through 19 for hookup diagrams of typical powering

applications.

Wallplate (Heating-only wallplate included)

Refer to Fig. 5 and strip thermostat wire insulation as

necessary.

For heating-only systems, connect wires to R, W and C

if applicable) terminals. See Fig. 20. Firmly tighten screws.

(

Push excess wire back into the wall.

JUMPER WIRES

Plug the hole in the wall with nonhardening caulk, putty,

or nonflammable insulation to prevent drafts from affect-

THERMOSTAT

BASE

WALLPLATE

OR SUBBASE

CAPTIVE

MOUNTING SCREWS

M3408

ing thermostat operation.

NOTE: For cooling only or heating-cooling applications,

refertoInstallationInstructionspackedwiththewallplate

or subbase.

INSERT CLOCK BATTERIES

Power is supplied to the clock by the 24 Vac transformer

or two AAA alkaline batteries (included), or by the heating

or cooling control circuit. Backup batteries may be in-

stalled to supply power to the clock if power is interrupted

when using 24 Vac powering method.

Fig. 5—Methods of connecting terminals.

Install the batteries in the thermostat. See Fig. 7.

Once a year or when batteries are dead, replace with two

new AAA alkaline batteries. We recommend Energizer

FOR STRAIGHT

CONNECTION

STRIP 5/16 in. [8 mm]

batteries.

FOR WRAPAROUND

CONNECTION

STRIP 7/16 in. [11 mm]

BARRIER

Fig. 7—Insert clock batteries.

BATTERY LOCATION FOR

(2) AAA BATTERIES;

M1556B

INSTALL WITH POSITIVE

ENDS UP

MOUNT THE THERMOSTAT

Note the tabs on the top inside edge of the thermostat

base. These tabs fit the slots molded into the top of the

wallplate or subbase.

Hang thermostat base on wallplate or subbase.

Insert the two captive mounting screws located in the

bottom corners of the base. See Fig. 6.

Firmly tighten the screws.

M7188

9-0750—1

SET CLOCK

Adjust the clock by moving the minute hand in a clock-

Adjust the heat anticipator lever to match the current

rating of the primary control for the proper cycle rate

wise

direction. Do not reverse the minute hand.

(Fig. 9). Set adjustable anticipation for total current of heat

When time is correctly set, the time indicator arrow

and fan control.

(

Fig. 8) must point to the correct time and the corresponding

daytime (light) or nighttime (dark) portion of the program

dial.

Locate the current rating stamped on the control or valve

Fig. 10), or the setting given in the device instructions.

(

If no current rating or heat anticipator setting is given,

measure the current with an ammeter. Proceed with the

following steps.

Fig. 8—Set clock.

PROGRAM DIAL

Fig. 9—Adjust heat anticipator.

MINUTE

HAND

TIME

INDICATOR

ARROW

M1813A

SET HEAT ANTICIPATOR

If T8090 is used on a steam system, skip to Attach

Thermostat Cover section. When used on any other heating

system, cut the two black heat anticipator jumper wires. See

Fig. 9. Follow the remaining section steps.

Fig. 10—Current rating of primary control.

SHOWS

CURRENT

DRAW

SHOWS

VOLTAGE

30 VACRATING

0.2 AMP

SHOWS

VOLTAGE

RATING

V8043E 1004 4

4V 50/60CY

SHOWS

ANTICIPATOR

SETTING

.32 AMP @ 60CY

SHOWS

VOLTAGE

RATING

BURNER

24 Vac 50/60 Hz

0.4 AMP

FROM MAIN

SHOWS

FUEL SUPPLY

ANTICIPATOR

SETTING

ZONE VALVE

TYPICAL GAS VALVE

OIL BURNER CONTROL

M6116B

69-0750—1

Remove the thermostat from the wallplate or subbase.

Connect an ac ammeter of appropriate range (about 0A to

SET SUBBASE SWITCHES (IF APPLICABLE)

The subbase system switch controls system operation as

follows:

2A) between the R and W terminals on the wallplate or

subbase except for electric heat and heat pump systems.

Let the system operate for one minute.

Adjust the heat anticipator lever to match the number

that reads on the ammeter.

HEAT: Heating system is controlled by the thermostat.

Cooling system is off.

COOL: Cooling system is controlled by the thermostat.

Heating system is off.

OFF: Both the heating and cooling systems are off. If the

fan switch is in the AUTO position, the fan is also off.

The subbase fan switch controls fan operation as follows:

ON: Fan operates continuously.

AUTO: Fan operates with the cooling equipment as

controlled by the thermostat or with the heating equip-

ment as controlled by the plenum switch. In electric

heat, heat pump and fan coil systems, the fan is

controlled by the thermostat for heating and cooling.

To switch positions, use thumb or index finger to slide

lever to the desired position. Switch lever must stop in

detent over the desired function indicator mark for proper

circuit operation.

ATTACH THERMOSTAT COVER

Make sure the packing inserts in the thermostat base are

removed.

Place the two tabs on the upper edge of the cover into the

mounting slots in the thermostat base. See Fig. 11.

Swing the cover downward until it catches at the bottom

of the base.

Fig. 11—Attach cover.

Checkout

50 60

CAUTION

Do not check operation by shorting across termi-

nals of system controls. This will damage the heat

anticipator.

M1519

HEATING-ONLY SYSTEM

Turn on power to the furnace.

Push together both temperature setting levers at least 5° F

3° C] above room temperature. The main burner should

come on. The fan will start when the furnace heats up.

Move both levers 5° F [3° C] below room temperature.

The burner should shut off.

Operate the entire heating system at least one complete

cycle.

If thermostat fails any test, refer to the Troubleshooting

Guide in the Owner’s Manual.

SET TEMPERATURE CONTROL LEVERS

The two levers on top of the thermostat control the low

and high temperatures for energy savings and comfort

control. See Fig. 12. The lever on the left (blue mark)

controls the lower temperature. The lever on the right (red

mark) controls the higher temperature.

We recommend pushing the levers together at an appro-

priate temperature for either heat or cool until the occupant

programs the thermostat and makes the final temperature

selections.

[

Reset both temperature setting levers to the desired tem-

peratures.

COOLING-ONLY SYSTEM

Fig. 12—Temperature control levers.

Turn on power to the cooling equipment.

Push both temperature setting levers together at least

° F [3° C] below room temperature. The cooling equip-

LOW TEMPERATURE

BLUE MARK)

SET LEVER

HIGH TEMPERATURE

(RED MARK)

SET LEVER

(

ment should operate, and the fan should start. Allow for any

time delay that may be built into the compressor control

circuit.

NOTE: To avoid compressor damage, do not operate the

system when outdoor temperature is below 50°F [10°C].

Refer to manufacturer recommendations.

60 70

M859

Move both levers 5° F [3° C] above room temperature.

The cooling equipment and the fan should shut off.

Operate the entire cooling system at least one complete

cycle.

9-0750—1

If thermostat fails any test, refer to the Troubleshooting

Guide in the Owner’s Manual.

Reset both temperature setting levers to the desired

5. If the readings are different, insert a small screwdriver

in the thermometer and turn it until the thermometers have

the same reading. See Fig. 13.

temperatures.

6. Replace the thermostat cover and put the system into

operation.

HEATING/COOLING SYSTEM

Turn on power to the furnace and cooling system.

Place the system switch lever to HEAT and fan switch

lever to AUTO.

NOTE: Radiant heat from your hands will offset the ther-

mometer reading. After making each adjustment, wait

five or ten minutes for the thermometer to stabilize before

comparing.

Push both temperature setting levers together at least

° F [3° C] above room temperature. The main burner

should come on. The fan will start when the furnace heats

up. (If central electric heat, fan coil or heat pump system,

fan starts immediately.)

Fig. 13—Thermometer calibration.

Move both levers 5° F [3° C] below room temperature.

The burner should shut off.

Place the system switch lever to COOL and the fan

switch lever to AUTO. The cooling equipment will oper-

ate, and the fan will start. Allow for any time delay that may

be built into the compressor control circuit.

NOTE: To avoid compressor damage, do not operate the

system when outdoor temperature is below 50°F [10°C].

Refer to manufacturer recommendations.

INCREASE

Move together both temperature setting levers at least

° F [3° C] above room temperature. The cooling equip-

ment should shut off.

Place the fan switch to ON. The fan should run continu-

ously with the system switch in any position.

Place the system switch to OFF. Move both temperature

setting levers to various positions. The heating and cooling

systems should not operate.

M5128

Operate the entire system for at least one complete cycle

with the system switch at COOL and one complete cycle

with the switch at HEAT.

If thermostat fails any test, refer to the Troubleshooting

Guide in the Owner’s Manual.

Reset both temperature setting levers to the desired

temperatures.

Leave Owner’s Manual and assistance information in a

convenient place for the building occupant or provide with

other appliance manuals.

THERMOSTAT

This thermostat was calibrated at the factory and should

not need recalibration in the field. If recalibration seems

necessary, first be sure wallplate or subbase is accurately

leveled. Then check thermometer calibration.

To check thermostat calibration, allow several hours of

operation after installation. Then read the thermometer and

remove the cover. Push the temperature levers together to a

setting the below room temperature. Slowly move them up

the scale together until the mercury slides across the tube.

IF THE THERMOMETER READING AND THE HIGH

TEMPERATURE LEVER POSITION ARE APPROXI-

MATELY THE SAME AT THE INSTANT THE MER-

CURY MOVES TO THE OTHER END, NO

RECALIBRATION IS NEEDED.

If calibration is necessary, proceed as follows:

1. Remove the cover.

2. Place open-end calibration wrench, part no. 104994A

(ordered separately), on the hex nut under the bimetallic coil

controlled by the red lever. See Fig. 14. Hold lever so it does

not move, and gently turn the wrench clockwise

the mercury rests securely in the right end of the tube.

3. Put the thermostat cover on and wait ten minutes.

4. Read the thermometer. Then remove the cover. Mov-

ing both levers, place the HIGH lever at the thermometer

reading. Hold lever so it does not move, and gently turn the

Calibration

THERMOMETER

The thermometer in your thermostat was accurately

calibrated at the factory. The thermometer should need

adjustment only if it has been dropped or shifted due to

mishandling. If the setpoint lever and the thermometer

reading do not agree:

. Remove the thermostat cover by pulling up from the

bottom of cover until it clears the mounting slots.

. Set the thermostat cover on a table near an accurate

thermometer.

until

3. Allow five minutes for cover thermometer to sense

area temperature; compare the readings. Be careful not to

touch thermometer or breathe on it.

. If the readings are the same, replace the cover and put

wrench counterclockwise

to the left end of the tube but no farther. Try to do this quickly

until the mercury just slides

the system into operation.

so the heat from your hands does not affect the thermostat.

5. Repeat this procedure for the blue lever.

69-0750—1

Fig. 14—Use of 104994A calibration wrench.

Fig. 17—Typical hookup for clock powered by

system transformer. Clock powered by battery

when system is not powered (e.g., power to

system is off or interrupted).

CALIBRATION

WRENCH

CLOCK

ANTICIPATOR

SETTING

LEVER

BATTERY

THERMOSTAT

ANTICIPATOR

SCALEPLATE

M8583

SUBBASE

HEAT

RELAY

HOT)

(

Typical Wiring Diagrams

POWER SUPPLY. PROVIDE DISCONNECT MEANS

AND OVERLOAD PROTECTION AS REQUIRED.

M1513A

Fig. 15—Typical hookup for clock powered by

separate 24 Vac transformer.

CLOCK

Fig. 18—Typical hookup for clock powered

through control system. Clock powered by

battery when heating or cooling equipment is

on; clock takes power from system when

heating equipment is off.

BATTERY

THERMOSTAT

CLOCK

SUBBASE

HOT)

(

BATTERY

HEAT

RELAY

HOT)

(

POWER SUPPLY. PROVIDE DISCONNECT MEANS

AND OVERLOAD PROTECTION AS REQUIRED.

BATTERY BACKUP MAY BE USED IF POWER TO

CLOCK IF INTERRUPTED.

SUBBASE

M1512B

HEAT

RELAY

(HOT)

Fig. 16—Typical hookup for clock powered by

two AAA alkaline batteries only.

COMPRESSOR

CONTACTOR

HOT)

(

CLOCK

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND

OVERLOAD PROTECTION AS REQUIRED.

BATTERY

JUMPER RH-RC TERMINALS WHEN ONE TRANSFORMER

POWERS BOTH HEATING AND COOLING.

THERMOSTAT

FOR POWER STEALING ON HEATING, JUMPER

C-RH AND C-W TERMINALS.

M1514C

SUBBASE

HEAT

RELAY

HOT)

(

POWER SUPPLY. PROVIDE DISCONNECT MEANS

AND OVERLOAD PROTECTION AS REQUIRED.

M1511A

9-0750—1

Fig. 19—Typical hookup for clock powered through control system. Clock powered by battery when

heating or cooling equipment is on; clock takes power from system when cooling equipment is off.

THERMOSTAT

CLOCK

BATTERY

SUBBASE

HEAT

RELAY

(HOT)

COMPRESSOR

CONTACTOR

(HOT)

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND

OVERLOAD PROTECTION AS REQUIRED.

JUMPER RH-RC TERMINALS WHEN ONE TRANSFORMER

POWERS BOTH HEATING AND COOLING.

FOR POWER STEALING ON HEATING, JUMPER

C-RC AND C-Y TERMINALS.

M720A

Fig. 20—Internal schematic and typical hookup for T8090A Thermostat/191108AJ Wallplate in heating-

only system.

CLOCK

THERMOSTAT

HEAT

ANTICIPATOR

FALL

HEAT

ANTICIPATOR

WALLPLATE

HEAT

RELAY

(HOT)

POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.

FOR STEAM SYSTEM, KEEP JUMPER IN PLACE. FOR NON STEAM SYSTEM, CUT AND

TAPE-OFF THE JUMPER AND ADJUST HEAT ANTICIPATOR FOR PROPER EQUIPMENT CYCLING.

M5349A

69-0750—1

Automation and Control Solutions

Honeywell International Inc. Honeywell Limited—Honeywell Limitée

985 Douglas Drive North

Golden Valley, MN 55422

35 Dynamic Drive

Scarborough, Ontario M1V 4Z9

9-0750—1

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