Honeywell T7079A Operation manual

PRODUCT DATA
Put UPC Code Here
63-2572—04
T7079A,B
Solid State
Remote Temperature Controllers
APPLICATION
The T7079 Electronic Remote Sensor Temperature Controller
is capable of providing on-off temperature control for ducts,
tanks, heating and refrigeration units, greenhouses, animal
confinement buildings and other applications where electronic
accuracy in addition to remote sensing is desired.
FEATURES
• Switch selection of heat or cool mode.
• Temperature sensing up to 400 feet.
• Does not require field calibration.
• 10K NTC temperature sensor.
• Wide setpoint temperature range.
• LED annunciation for both power on and relay state.
• Dual setpoint scale (°F and °C).
• Isolation transformer for 24 Vac input.
• Single- or Dual-stage output.
• Dual-stage output models can be configured as
two-heat, two-cool, or one-heat/one-cool.
Contents
Application ........................................................................1
Features ...........................................................................1
Specifications ....................................................................2
Ordering Information .........................................................2
Installation ........................................................................3
Wiring ...............................................................................4
Operation ..........................................................................5
Checkout ..........................................................................6

T7079A,B SOLID STATE REMOTE TEMPERATURE CONTROLLERS
63-2572—04 2
ORDERING INFORMATION
When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the
TRADELINE® 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 or
phone:
1. Your local Honeywell Automation and Control Products Sales Office (check white pages of your phone directory).
2. Honeywell Customer Care
1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386
In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Toronto, 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.
SPECIFICATIONS
Models:
T7079: On-off wall-mount control with one temperature input
and one or two relay output stages. Differential range of
1 to 30°F. Includes one sensor. See Table 1.
Table 1. T7079 models.
Dimensions: See Fig. 1.
Fig. 1. Dimensions of T7079 in in. (mm).
Electrical Ratings:
Voltage Input: 24 Vac, 50/60 Hz (+10%, -15%), Class 2 only.
120/230 Vac, 50/60 Hz (+10%, -15%).
Power Consumption: See Table 2.
Table 2. Power consumption ratings.
Contact Ratings:
At 120 Vac: 1/2 hp, 9.8 FLA, 58.8 LRA.
At 230 Vac: 1/4 hp, 4.9 FLA, 29.4 LRA.
At 120/230 Vac: 125 VA pilot duty.
At 24 Vac (resistive): 8A.
Ambient Ratings:
Operating Temperature: -40°to 140°F (-40°to 60°C).
Storage Temperature: -40°to 180°F (-40°to 82°C).
Operating Humidity: 5% to 95% RH non-condensing.
Temperature Accuracy (at nominal voltage): In 77°F
(25°C) ambient, nominal sensor value: ±2°F.
NOTE: Accuracy can vary based on deviation from nominal
values of input voltage, operating ambient and
sensor ambient.
Sensor: 10k NTC, 400 ft maximum distance between sensor
and electronic controller. See Table 3 for thermistor output.
Approvals:
Underwriters Laboratories, Inc.
Canadian Underwriters Laboratories.
CE.
Accessories:
107048 Heat Conduction Compound, 4 once.
107324A Bulb Holder, duct insertion.
121371A Copper Immersion Well.
121371E Stainless Steel Well.
32004800-001 10K NTC Sensor.
T7047C1090 Wall Mounted Sensor Case.
Voltage (in Vac) Setpoint Range in °F (°C)
24 120/230
-25 to 105
(-32 to 40)
100 to 240
(38 to 116)
T7079A1004 X X
T7079A1012 X X
T7079A1046 X X
T7079A1053 X X
T7079B1028 X X
T7079B1036 X X
T7079B1044 X X
T7079B1051 X X
STAGE1 STAGE2 POWER
2 (50)
2-7/16 (61)
1 (25)
2 (50)
4-1/2
(114)
7-3/16
(183)
2-7/16 (61)
M17560
Voltage Hz Nominal VA Maximum VA
24 50 5.6 6.2
60 5.5 6.1
120 50 7.7 8.5
60 5.6 6.2
230 50 5.0 6.1
60 2.9 4.7

T7079A,B SOLID STATE REMOTE TEMPERATURE CONTROLLERS
363-2572—04
Table 3. 10K thermistor output.
INSTALLATION
When Installing this Product...
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous
condition.
2. Check the ratings given in the instructions and on the
product to make sure the product is suitable for your
application.
3. Installer must be a trained, experienced service
technician.
4. After installation is complete, check out product
operation as provided in these instructions.
IMPORTANT
All wiring must agree with applicable codes,
ordinances and regulations.
CAUTION
Electrical Shock or Equipment Damage Hazard.
Can shock individuals or short equipment
circuitry.
Disconnect power supply before installation.
Location and Mounting
Mount the controller on a convenient interior location using the
three mounting holes provided on the back of the enclosure
(mounting screws are not provided and must be obtained
separately). Use controller dimensions in Fig. 1 as a guide.
Sensor Location
The sensor can be located up to 400 feet (122 meters) from
the T7079 using standard AWG 18/2 unshielded wire. The
sensor may be attached to pipes, in an immersion well, in a
wall-mounted case or on a bulb holder.
NOTES:
— For cable runs greater than 25 feet, shielded cable
is recommended.
— Multiple sensors can be parallel-series wired to
sense average temperatures in large spaces.
See Fig. 2.
— To maintain control accuracy, the number of
sensors wired parallel-series must be n2
(examples: 4, 9, 16).
Fig. 2. Parallel-series wiring of sensors.
Sensor Mounting
IMPORTANT
The T7079 is an operation control, not a limit or safety
control. If used in applications requiring safety or limit
controls, use a separate safety or limit control device
in conjunction with the T7079.
Mount the sensor(s) in one of the following manners:
— Hot/cold water sensing: Strap sensor to a pipe or insert in a
well (see Fig. 3).
— Space temperature sensing: Mount on a wall or panel
(see Fig. 4).
— Duct air sensing: Tape to a standard cap or bulb holder.
Fig. 3. Sensor inserted in an immersion well.
Resistance °C °F
97820 -20 -4
32740 0 32
19920 10 50
12500 20 68
10000 25 77
8056 30 86
5326 40 104
3604 50 122
2491 60 140
1756 70 158
1261 80 176
920.9 90 194
TO T7079
SENSORS
M13129
M5249
SENSOR PLACED
IN WELL
IMMERSION
WELL
1/2 NPT
COVER SENSOR
LEADS WITH
HEAT CONDUCTIVE
COMPOUND

T7079A,B SOLID STATE REMOTE TEMPERATURE CONTROLLERS
63-2572—04 4
Fig. 4. Wall-mounted sensor.
WIRING
CAUTION
Electrical Shock or Equipment Damage Hazard.
Can shock individuals or short equipment
circuitry.
Disconnect power supply before installation.
Refer to Fig. 5 for locating the appropriate power input, remote
sensor input and stage output terminals. To access the
terminals, remove the four cover screws and lift off the cover.
Refer to Fig. 6 and 7 for typical wiring.
IMPORTANT
Erratic temperature readings from the sensor can be
caused by poor wiring practices that must be avoided
to ensure proper operation:
1. Do not route the temperature sensor wiring with build-
ing power wiring.
2. Do not locate the temperature sensor wiring next to
control contactors.
3. Do not locate the temperature sensor wiring near
electrical motors.
4. Do not locate the temperature sensor wiring near
welding equipment.
5. Make sure good mechanical connections are made to
both the sensor and the control.
6. Use 90°C copper wire.
Fig. 5. Board layout for T7079.
NOTES:
1. The larger conduit knockout on the enclosure
bottom is for line-voltage applications.
2. The smaller knockout on the enclosure bottom is
for low-voltage applications.
3. The sensor knockout is at the enclosure top.
Fig. 6. Typical low-voltage (24 Vac) wiring application.
M13130
SENSOR
T7047C1090
WALLMOUNT SENSOR
CASE (OPTIONAL)
CAUTION: POSITION SENSOR AWAY
FROM SCREW TERMINALS.
SCREW
TERMINAL
SCREW
TERMINAL
LEADWIRES
TO T7079
LD1
J5 J4 J3
SENSOR J1
DIFF2
DIFF1 INTER
COOL HEAT
LD2
PWR
NC NO NOCOM NC COM COM120V240V
M17561
J2
24 VAC
1
1
1
1 3
2
TWO-STAGE MODELS ONLY.
LOW-VOLTAGE MODELS ONLY.
LINE-VOLTAGE MODELS ONLY.
1
2
3
STAGE 2 LED POWER LED
STAGE 1 LED
SENSOR
TERMINALS
STAGE DIFFERENTIAL
ADJUSTMENTS
INTERSTAGE
DIFFERENTIAL
OUTPUT STAGE
SWITCHING
VOLTAGE INPUT
J5 J4
SENSOR J1
NC NO NOCOM NC COM
M17562
J2
24 VAC
STAGE 2
LED
STAGE 1
LED
L1
(HOT) L2

T7079A,B SOLID STATE REMOTE TEMPERATURE CONTROLLERS
563-2572—04
Fig. 7. Typical line-voltage (120 Vac) wiring application.
OPERATION
Control Algorithm
On/Off Control
When used in heating mode, the relay is:
— Energized at setpoint minus differential on temperature fall.
— De-energized at setpoint on temperature rise.
When used in cooling mode, the relay is:
— Energized at setpoint plus differential on temperature rise.
— De-energized at setpoint on temperature fall.
NOTE: Each stage LED lights when its stage is energized.
The power LED lights when the controller is
connected to 120/230 or 24 Vac.
Differential (Stage and Interstage)
Adjustment
The stage and interstage differential values are adjusted using
the internal potentiometers (see Fig. 8). Values for setting are
marked on the inside cover:
— Minimum stage differential (DIFF1 or DIFF2): 1°F.
— Interstage differential: 0°F to 35°F.
NOTES:
— Actual minimum differential is typically between
1°F and 4°F. It is influenced by device tolerances
and the rate of temperature change.
— The setpoint knob setting is the stage 1 setpoint.
— The stage 2 setpoint is created using the stage 1
setpoint and the interstage differential:
— When stage 2 is used for heating, the stage 2
setpoint is the stage 1 setpoint minus the inter-
stage differential.
— When stage 2 is used for cooling, the stage 2
setpoint is the stage 1 setpoint plus the inter-
stage differential.
Fig. 8. Adjustments (potentiometers and switches).
TWO-STAGE HEAT
1. Set ST1 and ST2 switches to HEAT.
2. Set interstage (INTER) and differential (DIFF1, DIFF2) to
desired settings.
3. Position the setpoint knob at the setting for stage 1.
TWO-STAGE COOL
1. Set ST1 and ST2 switches to COOL.
2. Set interstage (INTER) and differential (DIFF1, DIFF2) to
desired settings.
3. Position the setpoint knob at the setting for stage 1.
ONE-STAGE HEAT/ONE-STAGE COOL
1. Set ST1 switch to HEAT and ST2 switch to COOL.
2. Set interstage (INTER) and differential (DIFF1, DIFF2) to
desired settings.
3. Position the setpoint knob at the setting for stage 1.
NOTE: See Fig. 9 for an example setup.
Fig. 9. Example one-stage heat/one-stage cool setup.
NOTE: Keep in mind that, based on the terminal board
labels, the stage 1 relay is J4; the stage 2 relay is J5.
J5 J4
SENSOR J1
M17563
STAGE 2
LED
STAGE 1
LED
L1
(HOT) L2
NC NO NOCOM NC COM COM120V240V
DIFF2
ST2 ST1
DIFF1 INTER
COOL HEAT
M17573
0
10
35
25
1
10
30
20
1
10
30
20
ST1: HEAT
ST2: COOL
DIFF1: 2°F
DIFF 2: 4°F
INTER: 6°F
80°F
76°F
70°F
68°F
SETPOINT
SETPOINT
KNOB SETTING:
M21062
STAGE 2 DIFFERENTIAL 2
DIFFERENTIAL 1
INTERSTAGE
STAGE 1
COOL ON
COOL OFF
HEAT OFF
HEAT ON

T7079A,B SOLID STATE REMOTE TEMPERATURE CONTROLLERS
63-2572—04 6
CHECKOUT
CAUTION
Compressor Damage Possible.
Rapid cycling can damage compressor and
overload electrical circuits.
When controlling a compressor, allow at least 5
minutes between cycles to equalize internal pressure.
NOTES:
— Checkout will depend on the type of hookup and
controlled equipment.
— Keep in mind that, based on the terminal board
labels, the stage 1 relay is J4; the stage 2 relay is
J5.
With the controller installed and wired, use the following
procedure:
1. Verify all settings.
2. Apply power.
3. Check for proper equipment response.
a. Cooling applications: turn the setpoint knob
counterclockwise until the stage LED lights.
b. Heating applications: turn the setpoint knob
clockwise until the stage LED lights.
NOTE: The stage LED indicates a call for cool/heat.
When it lights, the equipment should respond.

T7079A,B SOLID STATE REMOTE TEMPERATURE CONTROLLERS
763-2572—04

Automation and Control Solutions
Honeywell International Inc. Honeywell Limited-Honeywell Limitée
1985 Douglas Drive North 35 Dynamic Drive
Golden Valley, MN 55422 Toronto, Ontario M1V 4Z9
customer.honeywell.com
T7079A,B SOLID STATE REMOTE TEMPERATURE CONTROLLERS
® U.S. Registered Trademark
© 2009 Honeywell International Inc.
63-2572—04 K.K. Rev. 07-09