Page 1
T775A,B,C,D
Remote Temperature Controller
The T775 family of Electronic Remote Temperature Controllers provide on-off temperature
control for ducts, tanks, chillers, heating and refrigeration units, and other applications where
electronic accuracy in addition to remote sensing
is desired.
In addition, certain models of the T775 family
of controllers provide on-off temperature control
of heating, cooling, and ventilating systems in agricultural confinement buildings, storage areas and
heavy industrial applications.
■ T775A models provide staged on-off control with
one temperature input and one to four relay output
stages.
■ T775B models provide staged on-off control with
two temperature inputs and two to four relay output
stages.
■ T775C models provide staged on-off control with
one temperature input and four relay output stages.
■ T775D models provide staged on-off control with
two temperature inputs and four relay output stages.
■ T775C,D models meet National Electrical Code
(Article 547) requirements for animal confinement
buildings.
■ Setpoint temperature range is -40° to +220° F (-40°
to +104°C).
■ Ambient temperature range is -30° to +140°F for
one and two stage models and -30° to +125°F for
three and four stage models.
T775A,B
■ Adjustable temperature range and differential.
■ LCD indication for mode and output status.
■ Keypad provides ease of programming and operation.
■ Accuracy is within +/- 1°F (at nominal operating
ambient temperature of 77°F and voltage input).
■ Stage(s) independently programmed for heating or
cooling.
■ 24/120/240 Vac input voltage.
■ Spdt relay outputs.
IMPORTANT: The T775 is an operating control, not a
limit or safety control. If used in applications requiring safety or limit controls, a separate safety or limit
control device should be used in conjunction with the
T775.
T775C,D
■ Linear platinum temperature sensor with T775A,B.
■ Water-tight linear platinum temperature sensor with
T775C,D.
G.R. • 12-94 • ©Honeywell Inc. 1994
CONTENTS
Specifications ................................................. 2
Ordering Information ..................................... 2
Installation ..................................................... 5
Description/Operation ................................... 8
Checkout....................................................... 11
1 63-2489
63-2489
Page 2
T775A,B,C,D
SPECIFICATIONS • ORDERING INFORMATION
Specifications
IMPORTANT: The specifications given in this publication
do not include normal manufacturing tolerances.
Therefore, an individual unit may not exactly match
the listed specifications. Also, this product is tested
and calibrated under closely controlled conditions
and some minor difference in performance can be
expected if those conditions are changed.
MODELS: The T775A,B family of Electronic Temperature
Controllers for ducts, tanks, chillers, heating and refrigeration units, and other applications where electronic
accuracy is desired in addition to remote sensing.
T775A: Staged on-off control with one temperature input
and one to four relay output stages. Includes one
193987GA Sensor.
T775B: Staged on-off control with two temperature in-
puts and two to four relay output stages. Includes two
193987GA Sensors.
MODELS: The T775C,D family of Electronic Remote Tem-
perature Controllers provides on-off temperature control
of heating, cooling and ventilating systems in agricultural
confinement buildings, storage areas, and heavy industrial applications.
T775C: Staged on-off control with one temperature input
and four relay output stages. Mounted in NEMA 4X
enclosure. Includes one 203401B Remote Sensor.
T775D: Staged on-off control with two temperature inputs
and four relay output stages. Mounted in NEMA 4X
enclosure. Includes two 203401B Remote Sensors.
Maximum
Number
Model
Number
T775A1001 1 1 140
T775A1019 1 2 140
T775A1027 1 3 125
T775A1035 1 4 125
T775B1000 2 2 140
T775B1018 2 3 125
T775B1026 2 4 125
T775C1009 1 4 125
T775D1008 2 4 125
ELECTRICAL RATINGS:
Voltage Input: 24/120/240 Vac, 50/60 Hz (+10%/-15%).
Power Consumption:
For one and two stage units:
8 VA maximum at 60 Hz.
10 VA maximum at 50 Hz.
For three and four stage units:
13 VA maximum at 60 Hz.
20 VA maximum at 50 Hz.
Inputs
of
Number
of Relay
Outputs
Operating
Ambient
Temperature (°F)
Ordering Information
When ordering replacement and modernization products from your wholesaler or distributor, refer to the price lists 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 Home and Building Control Sales Office (check the white pages of your phone directory.
2. Home and Building Control Customer Logistics
Honeywell Inc., 1885 Douglas Drive North
Minneapolis, 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.
63-2489 2
Page 3
T775A,B,C,D
SPECIFICATIONS
CONTACT RATINGS:
1/2 hp; 9.8 FLA, 58.8 LRA at 120 Vac.
1/2 hp; 4.9 FLA, 29.4 LRA at 240 Vac.
125 VA pilot duty at 120/240 Vac.
10A at 24 Vac (resistive).
SENSOR: Positive coefficient platinum type, 4.8 ohms/ °F,
1000 ft maximum distance between sensor and solid
state controller (requires calibration over 400 ft). To
maintain NEMA 4X rating, use environmental proof
cable and sensor.
TEMPERATURE ACCURACY: +/-1°F (at nominal volt-
age in 77°F [25°C] ambient, nominal sensor value). Accuracy may vary based on deviation from nominal values of
input voltage, operating ambient and sensor ambient.
DISPLAY RESOLUTION: Sensed temperature and other
operating parameters are displayed via a liquid crystal
display (LCD) with a resolution of 1°F or 1°C.
SETPOINT ADJUSTMENT RANGE: -40° to 220°F (-40°
to 104°C).
OPERATING AMBIENT TEMPERATURE:
One and Two Stage units: -30° to 140°F.
Three and Four Stage units: -30° to 125°F.
OPERATING HUMIDITY: 5% to 95% relative humidity
(RH) noncondensing.
APPROVALS:
Underwriters Laboratories Inc. Listed: File no. E4436.
Canadian Standards Assoc. certified: File no. LR47125.
DIMENSIONS: See Fig. 1 and 2.
MOUNTING: Mounts on any suitable horizontal or vertical
surface (see Fig. 3 and 4 for mounting hole locations).
Fig. 1—Approximate dimensions of T775A,B in
in. (mm).
SET
SELECT
3-13/16 (97)
4-3/4 (121)
ENTER
5-7/32
(134)
7/8 (22) DIAMETER
8-1/2
(216)
2-3/8 (60)
1-1/4
(32)
1-1/4
(32)
M344C
Fig. 2—Approximate dimensions of T775C,D in in. (mm)
6 (153)
5-1/4 (133)
MOUNTING
HOLES
6-1/2
(165)
9
(229)
3-1/2 (89)
1-3/8
(34)
7/8 (22)
DIAMETER
1-1/4
(32)
M1301B
3 63-2489
Page 4
T775A,B,C,D
SPECIFICATIONS
Fig. 3—Feature locations for T775A,B.
LCD TEMPERATURE
DISPLAY
PROGRAMMING
KEYS
SENSOR INPUT,
TOD, AND 24VAC
TERMINALS
HOLE A
OUTPUT 2
KNOCKOUT B
RELAY OUTPUT STAGES
(MAXIMUM OF FOUR STAGES)
Fig. 4—Feature locations for T775C,D.
SENSOR
A
NC
COM
NO
SELECT
12
3
TOD
NO
COM
NC
OUTPUT 3
C \ F
SET
4
5
24V
6
SENSOR
B
ENTER
8
7
OUTPUT 1
NC
COM
NO
NO
COM
NC
120V
COM
240V
SA SB
°F/°C SELECTION
1
DIP SWITCHES FOR
2
3
SENSOR SELECTION.
4
PRESENT ON T775B
ONLY
MOUNTING HOLE
LOCATION
LINE VOLTAGE
INPUTS
KNOCKOUT C
OUTPUT 4
NOTE: T775A TERMINAL BLOCK CONTAINS ONLY
TERMINALS 1-6 AND HAS NO DIP SWITCHES
FOR SENSOR SELECTION
M7423
LCD TEMPERATURE
DISPLAY
PROGRAMMING
KEYS
SENSOR INPUT,
TOD, AND 24VAC
TERMINALS
HOLE A
EARTH
GROUND
WIRE
HOLE B
RELAY OUTPUT STAGES
SELECT
12
SENSOR
A
OUTPUT 2
NC
COM
NO
NO
COM
NC
OUTPUT 3
3
TOD
SET
C \ F
ENTER
1
2
3
4
°F/°C SELECTION
DIP SWITCHES FOR
SENSOR SELECTION.
PRESENT ON T775D
ONLY
SA SB
6
4
5
8
7
SENSOR
24V
B
MOUNTING
HOLES
OUTPUT 1
120V
NC
COM
COM
240V
NO
NO
COM
NC
OUTPUT 4
NOTE: T775C TERMINAL BLOCK CONTAINS ONLY
TERMINALS 1-6 AND HAS NO DIP SWITCHES
FOR SENSOR SELECTION
LINE VOLTAGE
INPUTS
HOLE C
M7427
63-2489 4
Page 5
T775A,B,C,D
SPECIFICATIONS • INSTALLATION
ACCESSORIES:
T775A,B:
A775A1003 Temperature Sensor Simulator.
C7100C Duct Mount Averaging Sensor.
198212CA Water Resistant Sensor.
203401B Water Tight Sensor.
T7047C1090 Wall Mounted Sensor Case.
107324A Bulb Holder, duct insertion.
121371A Copper Immersion Well.
121371E Stainless Steel Well.
WHEN INSTALLING THIS PRODUCT…
1. Read these instructions carefully. Failure to fol-
low 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 the product
operation as provided in these instructions.
WARNING
Disconnect power before installation to prevent
electrical shock or equipment damage.
LOCATION AND MOUNTING
Mount the controller on any convenient interior location
using the two mounting holes provided on the back of the
metal enclosure (mounting screws are not provided and
must be obtained separately). Use controller dimensions in
Fig. 1 (T775A,B) or Fig. 2 (T775C,D) as a guide.
SENSOR LOCATION
The 193987GA Sensor can be located up to 1000 feet
(304 meters) from the T775 using standard AWG 18/2
unshielded wire. For cable runs greater than 25 feet shielded
cable is recommended. See Fig. 5. It may be located on pipes,
in an immersion well, in a wall-mounted case or on a bulb
holder. See Fig. 6. The 193987GA is not a water tight or
water resistant sensor. For wet applications, see the Accessories list in the Specifications section.
Multiple sensors can be parallel-series wired to sense
average temperatures in large spaces.
To maintain control accuracy, the number of sensors
parallel-series wired must be of the n2 power (for example, 4,
9, 16, etc.). See Fig. 7.
107048 Heat Conduction Compound, 4 ounce.
C7043A1098 Case and Immersion Well for running
conduit to sensor.
T775C,D:
121371A Copper Immersion Well.
121371E Stainless Steel Well.
107408 Heat Conduction Compound, 4 ounce.
C7043A1098 Case and Immersion Well for running
conduit to sensor.
Installation
cap or bulb holder for duct air sensing. To prevent moisture
or condensation entering the sensor through the leadwire
holes, mount the sensor with the lead wires exiting the bottom of the sensor.
Fig. 5—Using shielded cable for cable runs
longer than 25 feet.
T775
C \ F
1
2
3
4
3
TOD
SET
4
5
24V
SENSOR
ENTER
6
8
7
SENSOR
B
OUTPUT 1
NC
COM
NO
OUTPUT 4
GROUNDING SCREW
NO
COM
NC
120V
COM
240V
SA SB
M7430
GROUND
SHIELD
TO T775
CABLE OR TO
GROUNDING
SCREW
SHIELDED
CABLE
SHIELDED
CABLE
NOTE: DO NOT GROUND
SHIELDED CABLE AT
SENSOR END.
NOTE: TO MINIMIZE NOISE PICKUP, MAKE CONNECTION
FROM SHIELDED CABLE AS CLOSE TO
SENSOR BODY AS POSSIBLE.
SELECT
12
SENSOR
A
OUTPUT 2
NC
COM
NO
NO
COM
NC
OUTPUT 3
NOTE: Use heat conductive compound in immersion wells.
See optional Accessories in the Specifications section.
SENSOR MOUNTING
Sensors can be mounted on a wall or panel for sensing
space temperature (Fig. 6), strapped to a pipe or inserted in a
well (Fig. 8) for hot/cold water sensing, or taped to a standard
CAUTION
Make sure that metal tube of sensor does not short
against T terminals in wall-mounted case.
5 63-2489
Page 6
T775A,B,C,D
INSTALLATION
Fig. 6—Sensor mounted on wall.
T7047C1090
WALLMOUNT SENSOR
CASE (OPTIONAL)
LEADWIRES
TO T775
SCREW
TERMINAL
SCREW
TERMINAL
CAUTION: POSITION SENSOR AWAY
FROM SCREW TERMINALS
BLACK LEAD
193987GA
SENSOR
WHITE LEAD
M8109A
Fig. 7—Parallel-series wiring of sensors.
SENSORS
TO T775 CONNECTIONS 1 AND 2 (SENSOR A)
OR 7 AND 8 (SENSOR B)
M7431
Fig. 8—Sensor inserted in immersion well.
COVER SENSOR
LEADS WITH
HEAT CONDUCTIVE
COMPOUND
SENSOR PLACED
IN WELL
1/2 NPT
IMMERSION
WELL
M5249
WIRING
WARNING
Disconnect power before installation to prevent
electrical shock or equipment damage.
Disconnect external power before wiring to prevent electrical shock or equipment damage. All wiring must comply
with applicable codes and ordinances.
IMPORTANT: The T775 is an operating 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 T775.
WARNING
Do not use 24 Vac power at terminals 5 and 6 to
power any external loads if 120 Vac or 240 Vac is
used to power the T775.
Refer to Fig. 3 or 4 for locating the appropriate power
inputs, remote sensor input, load output terminals, contact
closure input and sensor selection switch. Access to the
terminals can be gained through standard conduit knockouts
(A through C) located around the perimeter of the enclosure.
NOTE: Hole A should only be used for sensor, low-voltage
and contact closure wiring.
63-2489 6
Page 7
T775A,B,C,D
INSTALLATION
When wiring the input power, only one source of power
can be applied to the T775 (for example, 24 Vac or 120 Vac
or 240 Vac). Knockouts B and C can be used to gain access
to 120 Vac or 240 Vac input terminals and the load relay
output terminals.
See Fig. 11 through 14 for typical T775 wiring and
applications.
IMPORTANT: Erratic temperature readings from the
193987GA Sensor can be caused by poor wiring practices that must be avoided to assure proper operation:
• Do not route the temperature sensor wiring with
building power wiring.
• Do not locate the temperature sensor wiring next to
control contactors.
• Do not locate the temperature sensor wiring near
electrical motors.
• Do not locate the temperature sensor wiring near
welding equipment.
• Make sure good mechanical connections are made to
both the sensor and the controller.
• Do not mount the sensor with the leadwire end (wire
end) pointing up in an area where condensation can
occur.
If any of the above conditions cannot be avoided, use
shielded cable.
NOTE: Ground the cable shield at the T775 connection only,
not at the sensor connection ( see Fig. 5).
DEVICE SETUP
1. Determine the loads to be controlled and the operating
mode (heat or cool) and enter in the Device Programming
Worksheet.
For example: Load 1: Compressor 1 (cool)
Setpt 1 ______ On at _______
Diff 1 _______ Off at _______
2. For two sensor models (T775B), determine which
loads will be controlled from sensor A or sensor B and enter
on the worksheet.
For example: Load 1: Compressor 1 (cool)—Sensor A
Setpt 1 ______ On at _______
Diff 1 _______ Off at _______
3. Determine the setpoint (Setpt) and the switching dif-
ferential (Diff) for each load and enter on the worksheet.
For example: Load 1: Compressor 1 (cool)—Sensor A
Setpt 1 ______ On at _______
Diff 1 _______ Off at _______
4. Refer to the Control Algorithm subsection in Descrip-
tion/Operation section to calculate the load on and off temperatures. Enter them on the worksheet. Remember that the
on/off outputs are off at setpoint in both the heating and
78°F
4°F
cooling operating modes. When in cooling mode, the load
will be turned off at setpoint plus the differential. When in
heating mode, the load will be turned on at setpoint minus the
differential.
For example: Load 1: Compressor 1 (cool)—Sensor A
Setpt 1 ______ On at _______
Diff 1 _______ Off at _______
78°F
4°F
82°F
78°F
CAUTION
The T775 will not allow the user to program for
both heating and cooling loads to be energized at
the same time.
If this situation results, cooling loads will be
energized and heating loads will be prevented from
also energizing. The number (1,2,3,4) of these
nonenergized loads will flash along with the word
HEAT to indicate a call for both heating and cooling loads controlled by one sensor has occurred and
to alert the user to reprogram the affected control
values.
5. Remove the T775 cover and enter the values listed on
the worksheet and the date in the first column on the label
inside the T775 cover.
Device Programming Worksheet
Load 1:
SetPt 1 ______________ On at _______________
Diff 1 _______________ Off at _______________
Load 2:
Setpt 2 ______________ On at _______________
Diff 2 _______________ Off at _______________
Load 3:
Setpt 3 ______________ On at _______________
Diff 3 _______________ Off at _______________
Load 4:
Setpt 4 ______________ On at _______________
Diff 4 _______________ Off at _______________
DEVICE PROGRAMMING
Default Values
When power is initially applied to the T775, the control
points will be at their default value set at the factory. Default
values are:
Setpoint
(°F)
Stage 1 72 2 Heat
Stage 2 70 2 Heat
Stage 3 68 2 Heat
Stage 4 66 2 Heat
Differential
(°F)
Operating
Mode
7 63-2489
Page 8
T775A,B,C,D
INSTALLATION • DESCRIPTION/OPERATION
1. For the T775B and T775D, assign the loads to the
appropriate sensor by setting the DIP switch in the upper
right corner of the T775 (see DIP Switch Selection, Fig. 9).
2. Before programming the T775, verify that the °F/°C
selection jumper is properly installed. The T775 is shipped
from the factory with the jumper installed in the °F position.
If °C is desired, remove the jumper.
3. Apply power to the device. The device will begin
counting down from 210. This countdown sequence will last
for approximately 3-1/2 minutes.
4. Press Select to override this time delay.
5. Press Select and Enter keys simultaneously to begin
programming the load operating mode (Heat or Cool).
6. Press the Set (down arrow) to change to cooling. The
Set (up arrow) will change back to heating.
7. Press Enter to program the displayed mode into
memory.
8. Press Select to go to the next stage.
9. Repeat steps 6 through 9 for additional stages.
10. Press Select after the last stage is set up to return to the
display of the sensed temperature.
PROGRAMMING STAGE CONTROL VALUES
1. Press Select to display the current stage setpoint.
2. Press Set (up arrow) to increase or Set (down arrow) to
decrease to the desired setpoint.
3. Press Enter to enter the displayed value into memory.
4. Press Select to display the current stage switching
differential.
5. Press Set (up arrow) to increase or Set (down arrow) to
decrease to the desired switching differential.
6. Press Enter to enter the displayed value into memory.
7. Repeat steps 1 through 6 to program each additional
stage.
8. For the T775A and T775C, press Select/Select (two
times) to return to stage 1 parameters. For the T775B and
T775D, press Select/Select/Select/Select (four times) to return to stage 1 parameters. Scroll through the programming
loop a second time to confirm that the appropriate values
were entered into memory by pressing Select.
NOTE: The T775B and T775D have three options for dis-
playing the sensed temperature:
1. Sensor A only.
2. Sensor B only.
3. Alternating between Sensor A and Sensor B.
For the T775B and T775D only:
9. Press Select after viewing the switching differential
for the final stage to display Sensor A temperature only.
10. Press Select again to display Sensor B temperature
only.
11. Press Select again to alternate the display between
Sensor A temperature and Sensor B temperature at approximately five-second intervals.
12. Before replacing the cover on the T775, check to see
that the control values were recorded on the label on the
backside of the cover.
IMPORTANT: For the T775A and T775C only: After initial
programming, altering the setpoints for stage 1 up or
down will result in a change in setpoints 2, 3, and 4 by
the same number of degrees and in the same direction.
If increasing or decreasing the setpoint for stage 1
results in exceeding the control limits (-40° to +220°F
[-40° to +104°C]) for subsequent stages, the control
will not allow the user to enter a value for stage 1
higher or lower than this limit. This will allow for easy
sequential output staging to be modified while keeping
the margin intact between setpoints
CONTROL ALGORITHM
On/Off Control
The T775A and T775C operate with one temperature
input supplied by the remote sensor while T775B and T775D
have two temperature inputs. The T775A,B,C, and D are all
capable of providing up to four stages of relay outputs for
on/off control. Each stage of the T775A,B,C, and D has its
own independent setpoint that can be configured to operate
in either the heating or cooling mode. The mode of operation
for each stage is user determined by the programming keys.
Heating Mode Operation
• Relay outputs are energized at the temperature setpoint minus the differential value.
• Relay outputs are de-energized at the temperature setpoint value.
63-2489 8
Description/Operation
Cooling Mode Operation
• Relay outputs are energized at the temperature setpoint plus differential value.
• Relay outputs are de-energized at the temperature setpoint value.
EXAMPLE: Using a device with one input and one relay
output, the corresponding load would be energized at the
temperatures following based on the initial settings.
Settings
• Setpoint: 68°F
• Differential: 2°F
OUTPUTS ENERGIZED
Heating Mode:
• Stage One: Energized at 66°F.
Page 9
T775A,B,C,D
DESCRIPTION/OPERATION
Cooling Mode:
• Stage One: Energized at 70°F.
The T775B,D have dual sensor inputs and allow two
separate controllers to exist within one enclosure. Selection
of the stage parameters (operation mode, setpoints, and
differentials) is the same as for a single sensor device after
each stage is assigned its operating sensor. This assignment
is hardware driven via a four position DIP switch. An
explanation of the DIP switch assignments appears in Fig. 9.
See Fig. 3 and 4 for the DIP switch location.
CONTACT CLOSURE OVERRIDE INPUT
A two-terminal input is provided to allow the user to
override a relay-energized condition on all outputs by using
a contact closure between terminal pins 3 and 4 of the
terminal block for the sensor input shown in Fig. 3 and 4.
This can be achieved manually or by using an EMS controller or time clock with normally open contacts (W7505 or
S7005, for example).
When this override is active, the display will show the
number of the stages that would be energized and the words
STAGE ENERGIZED will flash on the display. The energized stages will then be de-energized until the override
returns to inactive (Off).
°F/°C SELECTION
A single jumper plug controls °F/°C indication of the
displayed temperature value. The location of this jumper is
shown in Fig. 3 and 4. The unit is shipped with the jumper
installed in the °F mode. To operate the device in the °C
mode, remove the jumper. Replacing the jumper will reinstate the °F mode.
DIP SWITCH SELECTIONS
On the T775B and D, the DIP switches are provided for
assignment of each relay output stage to its operating sensor.
If an individual switch is depressed toward its corresponding load number (1 through 4 on DIP switch) or to the right,
Sensor B will be the controlling sensor for that output stage.
If an individual switch is depressed to the left, Sensor A will
be the controlling sensor for the output stage. An example of
the switches and their corresponding positioning is shown in
Fig. 9.
KEYPAD PROGRAMMING AND DISPLAY
The T775 utilizes a Liquid Crystal Display (LCD) for
interactive prompting during programming and display of
sensed and assigned setpoint and differential values. User
programming of the T775 is accomplished through the four
programming keys.
Programming Keys
The four programming keys are the Select, Up arrow,
Down arrow and Enter keys.
• Select key sequentially prompts the user about what
parameter is being displayed: setpoint, differential,
stage energized, heat or cool (operation mode), 1,2,3,4
(indicating assigned stage). After the last parameter
value is viewed, pressing the Select key will again
display the control values from the beginning of the
display loop.
• Up and Down arrow keys allow the displayed parameter to be increased or decreased. After pressing the
Select key, a control value can be changed by using the
arrow keys. Control values will be increased or decreased by 1°F or 1°C for each time the arrow key is
depressed.
• Enter key places the new value into the memory of the
microprocessor.
IMPORTANT: A control value or operation will not be
entered into the memory of the microprocessor until
the Enter key is pressed.
• Press the Select and Enter keys at the same time to
change the control algorithm from heating to cooling
or from cooling to heating. The heating and cooling
parameters are not displayed during the normal Select
key sequences. The only parameters displayed after
pressing the Select and Enter keys at the same time
will be the stage indication and the word, heat or cool.
To change the operation from heating to cooling or
vice versa for a desired output stage, use the arrow
keys. Once the mode is changed, pressing the Enter
key is necessary to enter this change into the microprocessor memory. The next stage of heat or cool assignment will appear after the Select key is pressed. When
all stages are programmed, the display will revert back
to sensed temperature and load energized status.
Fig. 9—DIP switch settings for sensor selection.
SWITCH
SWITCH
PWB
PWB
AB
SIDE VIEW
SENSOR A SENSOR B
LOAD 1
LOAD 2
LOAD 1 IS CONTROLLED BY
SENSOR A WHEN SWITCH IS
DEPRESSED ON THE LEFT
LOAD 2 IS CONTROLLED BY
SENSOR B WHEN SWITCH IS
DEPRESSED ON THE RIGHT
(AS SHOWN)
M3292
Control values and operation selection will remain in the
device memory even after the power is removed.
Display
Once power is applied or restored to the device, the display will count down from 210 until the display reads zero,
during which time any previously energized outputs will be
de-energized. This is intended to protect compressors in the
event of a power outage.
To avoid viewing this entire countdown, press the Select
key. The LCD display will now show what it normally reads:
load (sensed) temperature, stages energized, and which sensor (Sensor A or Sensor B) is being read for two sensor
9 63-2489
Page 10
T775A,B,C,D
DESCRIPTION/OPERATION
devices. At any time during the programming procedure, the
display will revert back to showing the sensed temperature
and stage status indication 60 seconds after the last key
closure.
For two sensor applications, the user has three options for
what is displayed. The display can be configured to indicate
Sensor A and Sensor B sensed temperature at a five second
rate or lock onto Sensor A sensed temperature or lock onto
Sensor B sensed temperature continuously.
This selection is accomplished by stopping at Sensor A
or Sensor B sensed temperature points in the Select screen
scrolling loop. To lock on to either sensor, the user must
scroll the Select key through the loop to the sensed temperature prompt of interest. The display will remain at that
parameter until the Select key is activated to advance the loop.
When the loop is stopped at any other prompt, the display
will alternatively indicate Sensor A and Sensor B sensed
temperature after 60 seconds from the last key closure or
immediately after the Select key is pressed at the end of the
programming sequence.
Error Messages
There are seven error messages that can be displayed in
response to software or hardware problems with the T775.
The error Codes flashing on the display are:
SF—Sensor Failure
If the display shows a flashing SF, this indicates an outof-range or defective sensor. Make sure that the sensors are
connected properly. For T775A,C all loads will be deenergized when this error message is flashing.
For the T775B,D the loads controlled by the out-ofrange sensor will be de-energized. The display will flash SF
to indicate which sensor is defective or in error. In the event
that only one sensor is defective, the remaining sensor and its
load(s) will operate normally. Only the load(s) controlled by
the defective, out-of-range, or unconnected sensor will be
de-energized.
NOTE: Sensor values below -40°F or above 220°F will be
out-of-range.
EF—EEPROM Failure
The values read back from the EEPROM are not the same
as written into the EEPROM. This error cannot be field
repaired. Replace the device. The EEPROM is not intended
to be field repaired.
CF—Calibration Failure
A calibration resistor reading was not within the range of
the Analog to Digital converter. This error cannot be field
repaired. Replace the device.
OF—Stray Interrupt Failure
An unused interrupt occurred. This error cannot be field
repaired. Replace the device.
CE—Configuration Error
The device hardware was configured to a nonexistent
device. This error cannot be field repaired. Replace the
device.
OE—ROM Error
The internal Read Only Memory (ROM) of the microprocessor is defective. This error cannot be field repaired.
Replace the device.
AE—RAM error
The internal Random Access Memory (RAM) of the
microprocessor is defective. This error cannot be field repaired. Replace the device.
Setpoint Calibration
To maintain temperature accuracy, sensor wires should
be 18 AWG two-conductor. If the length of the sensor wire
exceeds 400 feet, recalibration will be necessary to maintain
accuracy. The chart that follows shows the corresponding
temperature offset to use for different sensor wire lengths.
This temperature offset should be added to the desired
temperature setpoint for these applications. Refer to programming instructions in the Programming section for entering temperature setpoints.
Sensor Wire Length Calibration Offset
0 to 399 ft None required.
400 to 599 ft 1.0 degrees
600 to 799 ft 2.0 degrees
800 to 1000 ft 3.0 degrees
63-2489 10
Page 11
T775A,B,C,D
CHECKOUT
Checkout
After the controller is installed and wired, apply power.
Make initial adjustments and desired settings.
1. As shown in Fig. 8, record the sensed temperatures for
both Sensor A and Sensor B as displayed on the device. Use
the Select key to advance through the programming loop to
determine and then write on the Checkout Table which loads
are controlled by each sensor.
2. Write the operating mode (heat or cool) for each stage
in the Checkout Table.
3. Write the sensed temperature for each load on the
Sensed Temp. line.
4. Write the differential for each load on the Differential
line.
5. Write the setpoint for each stage (Off temperature).
Calculate the On temperature for each stage. (On temperature is setpoint plus differential for cooling and is setpoint
minus differential for heating.)
6. Plot the on and off (open/closed) values at which the
device will energize and de-energize each output load, (Refer to the Device Programming Worksheet.)
7. Verify which loads are energized by using the Checkout Table. As shown in the example, the display will indicate, in the lower right corner, which stages are energized. If
no stages are energized, the words “stage energized” will not
appear.
NOTE: If the sensed temperature is between the On and Off
temperatures, the load may either be energized or deenergized. Refer to the Control Algorithm section for
further explanation.
8. If an error message flashes, refer to the description of
these messages. If SF flashes, check the sensor connections.
If properly connected and SF continues to flash, check the
sensor location to make sure it is located in an ambient condition that is within the sensor capability (-40° to +220°F).
9. If an error message other than SF flashes, the device
cannot be field repaired. Replace the device.
11 63-2489
Page 12
T775A,B,C,D
CHECKOUT
Fig. 10—Checkout Table and checkout example with Sensor A = 68°F and Sensor B = 73°F.
CHECKOUT EXAMPLE WITH SENSOR A = 68° AND SENSOR B = 73°
HEAT OR COOL
LOAD 1
(HEAT)
LOAD 2
(HEAT)
LOAD 3
(HEAT)
MODE
LOAD 4
(HEAT)
DIFFERENTIAL
DESIGNATED
SENSOR
SETPOINT
SENSED
TEMPERATURE
22
22
A BAB
70
OFF
ON
68
68
LOAD 1
IS ON
OFF72
ON
70
73 68
LOAD 2
IS OFF
STAGE ENERGIZED 1 3 4
SELECT ENTERSET
1
74
2
72
OFF
ON
1
76
2
74
73
LOAD 3
IS ON
LOAD 4
IS ON
OFF
ON
1
2
NOTE: RELAYS ARE DE-ENERGIZED AT SETPOINT
CHECKOUT TABLE
LOAD 1 LOAD 2 LOAD 3 LOAD 4
HEAT OR COOL
SETPOINT
DIFFERENTIAL
DESIGNATED
SENSOR
SETPOINT
SENSED
TEMPERATURE
INDICATES LOAD STATUS WHEN SENSED TEMPERATURE REACHES SETPOINT.
1
INDICATES LOAD STATUS WHEN SENSED TEMPERATURE REACHES SETPOINT
2
MINUS DIFFERENTIAL (HEAT MODE).
63-2489 12
M7426
Page 13
Fig. 11—Two-stage control, 24 Vac input, 24 Vac load.
SENSOR B
to pins 7 AND 8
for T775B, D
SENSOR
24 VAC
LOAD 2
LOAD 1
SELECT
12
SENSOR
A
OUTPUT 2
NC
COM
NO
3
TOD
C \ F
SET
ENTER
SA SB
6
4
7 8
5
24V
OUTPUT 1
120V
NC
COM
COM
240V
NO
DIP SWITCHES
FOR SENSOR
1
SELECTION.
2
PRESENT ON
3
4
T775B, D ONLY
TEMPERATURE
FALL
DIFFERENTIAL
2
SETPOINT 2
DIFFERENTIAL
1
SETPOINT 1
TEMPERATURE
FALL
COOL MODE
RELAY 1 AND 2
ENERGIZED
RELAY 1 ENERGIZED
NULL
HEAT MODE
NULL
RELAY 1 ENERGIZED
RELAY 1 AND 2
ENERGIZED
T775A,B,C,D
CHECKOUT
TEMPERATURE
RISE
SETPOINT 1
DIFFERENTIAL
#1
SETPOINT 2
DIFFERENTIAL
#2
TEMPERATURE
RISE
M7421
13 63-2489
Page 14
T775A,B,C,D
CHECKOUT
Fig. 12—Two-stage control, 120 or 240 Vac input; 120 or 240 Vac load.
SENSOR B
to pins 7 AND 8
for T775B, D
SENSOR A
120 VAC INPUT; 120 VAC LOADS
3
TOD
SET
6
4
7 8
5
24V
SELECT
12
SENSOR
A
ENTER
C \ F
SA SB
DIP SWITCHES
FOR SENSOR
1
SELECTION.
2
PRESENT ON
3
4
T775B, D ONLY
SENSOR B
to pins 7 AND 8
for T775B, D
SENSOR A
OUTPUT 2
NC
COM
NO
LOAD 1 LOAD 2
LOAD 1 LOAD 2
240 VAC INPUT; 240 VAC LOADS
3
TOD
SET
6
4
5
24V
SELECT
12
SENSOR
A
OUTPUT 1
NC
COM
NO
ENTER
7 8
120V
COM
240V
C \ F
SA SB
DIP SWITCHES
FOR SENSOR
1
SELECTION.
2
PRESENT ON
3
4
T775B ONLY
WHT
120 VAC
BLK
TEMPERATURE
FALL
DIFFERENTIAL 2
SETPOINT 2
DIFFERENTIAL 1
SETPOINT 1
TEMPERATURE
FALL
COOL MODE
RELAY 1 AND 2
ENERGIZED
RELAY 1 ENERGIZED
NULL
HEAT MODE
NULL
RELAY 1 ENERGIZED
RELAY 1 AND 2
ENERGIZED
TEMPERATURE
RISE
SETPOINT 1
DIFFERENTIAL 1
SETPOINT 2
DIFFERENTIAL 2
TEMPERATURE
RISE
OUTPUT 2
NC
COM
NO
LOAD 1 LOAD 2
LOAD 1 LOAD 2
OUTPUT 1
NC
COM
NO
120V
COM
240V
63-2489 14
RED
240 VAC
BLK
M7422
Page 15
Fig. 13—Four-stage control, 24 Vac input; 24 Vac load.
SELECT
12
SENSOR
A
SENSOR A
24 VAC
SENSOR B
to pins 7 AND 8
for T775B,D
3
TOD
T775A,B,C,D
CHECKOUT
C \ F
1
2
DIP SWITCHES
3
FOR SENSOR
4
SELECTION.
SET
ENTER
SA SB
6
4
5
8
7
SENSOR
24V
B
PRESENT ON
T775B,D ONLY
LOAD 4
TEMPERATURE
FALL
DIFFERENTIAL 3
SETPOINT 3
LOAD 3
RELAY 1,2 AND 3
ENERGIZED
LOAD 1
LOAD 2
COOL MODE
RELAY 1 AND 2
ENERGIZED
OUTPUT 2
NC
COM
NO
NO
COM
NC
OUTPUT 3
TEMPERATURE
FALL
OUTPUT 1
120V
NC
COM
COM
240V
NO
NO
COM
NC
OUTPUT 4
HEAT MODE
RELAY 1 ENERGIZED
NULL
DIFFERENTIAL 2
SETPOINT 2
DIFFERENTIAL 1
SETPOINT 1
N OTE: FOR THERMOSTAT APPLICATIONS, CONNECT NO CONTACT OF COOLING STAGE TO Y1 (AND SECOND STAGE TO Y2)
CONNECT NO CONTACT OF HEATING STAGE TO W1 (AND SECOND STAGE TO W2).
RELAY 1 ENERGIZED
NULL
TEMPERATURE
RISE
RELAY 1 AND 2
ENERGIZED
RELAY 1,2 AND 3
ENERGIZED
SETPOINT 1
DIFFERENTIAL 1
SETPOINT 2
DIFFERENTIAL 2
SETPOINT 3
DIFFERENTIAL 3
TEMPERATURE
RISE
M7425
15 63-2489
Page 16
T775A,B,C,D
CHECKOUT
Fig. 14—Four stage control, 120 or 240 Vac input, 120 or 240 Vac load.
SENSOR B
to pins 7 AND 8
for T775B, D
SENSOR A
120 VAC INPUT; 120 VAC LOADS
3
TOD
SET
6
4
5
24V
SELECT
12
SENSOR
A
OUTPUT 2
NC
COM
NO
NO
COM
NC
OUTPUT 3
8
7
SENSOR
B
OUTPUT 1
ENTER
120V
NC
COM
COM
240V
NO
NO
COM
NC
OUTPUT 4
C \ F
SA SB
1
2
3
4
DIP SWITCHES
FOR SENSOR
SELECTION.
PRESENT ON
T775B,D ONLY
WHT
120 VAC
BLK
TEMPERATURE
FALL
DIFFERENTIAL 4
SETPOINT 4
DIFFERENTIAL 3
SETPOINT 3
DIFFERENTIAL 2
SETPOINT 2
COOL MODE
RELAY 1,2,3 AND 4
ENERGIZED
RELAY 1,2 AND 3
ENERGIZED
RELAY 1 AND 2
ENERGIZED
RELAY 1 ENERGIZED
SENSOR B
to pins 7 AND 8
for T775B, D
SENSOR A
LOAD 4
SENSOR
A
OUTPUT 2
NC
COM
NO
COM
OUTPUT 3
LOAD 3
240 VAC INPUT; 240 VAC LOADS
3
TOD
SET
6
4
5
SENSOR
24V
B
T775A
SELECT
12
NO
NC
LOAD 2 LOAD 1
ENTER
8
7
OUTPUT 1
120V
NC
COM
COM
240V
NO
NO
COM
NC
OUTPUT 4
C \ F
SA SB
1
2
3
4
DIP SWITCHES
FOR SENSOR
SELECTION.
PRESENT ON
T775B,D ONLY
RED
240 VAC
BLK
DIFFERENTIAL 1
SETPOINT 1
TEMPERATURE
FALL
NULL
HEAT MODE
NULL
RELAY 1 ENERGIZED
RELAY 1 AND 2
ENERGIZED
RELAY 1,2 AND 3
ENERGIZED
RELAY 1 ,2,3 AND 4
ENERGIZED
TEMPERATURE
RISE
SETPOINT 1
DIFFERENTIAL 1
SETPOINT 2
DIFFERENTIAL 2
SETPOINT 3
DIFFERENTIAL 3
SETPOINT 4
DIFFERENTIAL 4
TEMPERATURE
RISE
LOAD 4
LOAD 3
LOAD 2 LOAD 1
M7424
Home and Building Control Home and Building Control Helping You Control Your World
Honeywell Inc. Honeywell Limited—Honeywell Limitée
1985 Douglas Drive North 740 Ellesmere Road
Golden Valley, MN 55422 Scarborough, Ontario
M1P 2V9
63-2489 16
Printed in U.S.A. www.honeywell.com/building/components
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