Home
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T775A,B,C,D  
Remote Temperature Controller  
PRODUCT DATA  
FEATURES  
•
•
•
•
•
•
•
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  
5
47) requirements for animal confinement buildings.  
Setpoint temperature range is -40° to +220°F (-40° to  
104°C).  
T775A,B  
T775A,B  
+
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.  
APPLICATION  
•
•
Linear platinum temperature sensor with T775A,B.  
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.  
Water-tight linear platinum temperature sensor with  
T775C,D.  
•
•
•
•
Adjustable temperature range and differential.  
LCD indication for mode and output status.  
Keypad provides ease of programming and operation.  
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.  
Accuracy is within +/- 1°F (at nominal operating  
ambient temperature of 77°F and voltage input).  
•
Stage(s) independently programmed for heating or  
cooling.  
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.  
•
•
24/120/240 Vac input voltage.  
Spdt relay outputs.  
Contents  
Application ........................................................................  
Features ...........................................................................  
Specifications ...................................................................  
Ordering Information ........................................................  
Installation ........................................................................  
Wiring ...............................................................................  
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Checkout .......................................................................... 10  
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T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
SPECIFICATIONS  
IMPORTANT  
Setpoint Adjustment Range: -40° to 220°F (-40° to 104°C).  
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.  
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.  
Operating Ambient Temperature:  
One and Two Stage units: -30° to 140°F.  
Three and Four Stage units: -30° to 125°F.  
Models (see Table 1):  
The T775A,B Electronic Temperature Controllers provide  
staged on-off temperature control for ducts, tanks, chillers,  
heating and refrigeration units, and other applications  
where electronic accuracy and remote sensing are desired.  
The T775C,D Electronic Remote Temperature Controllers  
provide staged on-off temperature control of heating,  
cooling and ventilating systems in agricultural confinement  
buildings, storage areas, and heavy industrial applications.  
Operating Humidity:  
5% to 95% relative humidity (rh) noncondensing.  
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.  
Dimensions: See Fig. 1 and 2.  
Electrical Ratings:  
Voltage Input: 24/120/240 Vac, 50/60 Hz (+10%/-15%).  
Power Consumption:  
Mounting: Mounts on any suitable horizontal or vertical  
surface (see Fig. 3 and 4 for mounting hole locations).  
For one and two stage units:  
8
VA maximum at 60 Hz.  
Temperature Accuracy: +/-1°F (at nominal voltage in 77°F  
10 VA maximum at 50 Hz.  
For three and four stage units:  
13 VA maximum at 60 Hz.  
20 VA maximum at 50 Hz.  
[
25°C] ambient, nominal sensor value). Accuracy may vary  
based on deviation from nominal values of input voltage,  
operating ambient and sensor ambient.  
Table 1. T775 Models.  
Maximum Operating  
Relay  
Inputs Outputs Ambient Temperature  
Model  
T775A1001  
T775A1019  
T775A1027  
T775A1035  
T775B1000  
T775B1018  
T775B1026  
T775C  
Comments  
1
1
1
1
2
2
2
1
2
1
2
3
4
2
3
4
4
4
140°F (60°C)  
140°F (60°C)  
125°F (52°C)  
125°F (52°C)  
140°F (60°C)  
125°F (52°C)  
125°F (52°C)  
125°F (52°C)  
125°F (52°C)  
Includes one 193987GA Sensor.  
Includes two 193987GA Sensors.  
NEMA 4X enclosure. Includes one 203401B Remote Sensor.  
NEMA 4X enclosure. Includes two 203401B Remote Sensors.  
T775D  
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).  
Honeywell Customer Care  
2.  
1
885 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.  
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3-2489—2  
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T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
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).  
SELECT  
SET  
ENTER  
Approvals:  
Underwriters Laboratories Inc. Listed: File no. E4436.  
Canadian Standards Assoc. certified: File no. LR47125.  
8
-1/2  
(216)  
Accessories:  
T775A,B:  
5
-7/32  
A775A1003 Temperature Sensor Simulator.  
C7100C Duct Mount Averaging Sensor.  
(
134)  
1
2
98212CA Water Resistant Sensor.  
03401B Water Tight Sensor.  
1-1/4  
32)  
(
T7047C1090 Wall Mounted Sensor Case.  
1
1
1
1
07324A Bulb Holder, duct insertion.  
21371A Copper Immersion Well.  
21371E Stainless Steel Well.  
1-1/4  
32)  
3
-13/16 (97)  
4-3/4 (121)  
(
07048 Heat Conduction Compound, 4 ounce.  
C7043A1098 Case and Immersion Well for running conduit  
to sensor.  
2-3/8 (60)  
M344C  
7
/8 (22) DIAMETER  
T775C,D:  
21371A Copper Immersion Well.  
1
Fig. 1. Approximate dimensions of T775A,B in in. (mm).  
121371E Stainless Steel Well.  
1
07408 Heat Conduction Compound, 4 ounce.  
C7043A1098 Case and Immersion Well for running conduit  
to sensor.  
6
(153)  
-1/4 (133)  
5
3
-1/2 (89)  
MOUNTING  
HOLES  
9
(
229)  
6
-1/2  
(
165)  
7
/8 (22)  
DIAMETER  
1
-1/4  
(
32)  
1
-3/8  
M1301B  
(
34)  
Fig. 2. Approximate dimensions of T775C,D in in. (mm)  
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63-2489—2  
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T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
LCD TEMPERATURE  
DISPLAY  
C \ F  
F/C SELECTION  
DIP SWITCHES FOR  
SENSOR SELECTION.  
PRESENT ON T775B  
ONLY  
PROGRAMMING  
KEYS  
SELECT  
SET  
ENTER  
SA SB  
MOUNTING HOLE  
LOCATION  
SENSOR INPUT,  
TOD, AND 24VAC  
TERMINALS  
1
2
3
4
5
6
7
8
HOLE A  
SENSOR TOD  
A
24V SENSOR  
B
LINE VOLTAGE  
INPUTS  
OUTPUT 2  
OUTPUT 1  
NC  
120V  
NC  
COM  
NO  
COM COM  
NO  
240V  
KNOCKOUT B  
NO  
COM  
NC  
KNOCKOUT C  
NO  
COM  
NC  
OUTPUT 3  
OUTPUT 4  
RELAY OUTPUT STAGES  
MAXIMUM OF FOUR STAGES)  
NOTE: T775A TERMINAL BLOCK CONTAINS ONLY  
TERMINALS 1-6 AND HAS NO DIP SWITCHES  
(
FOR SENSOR SELECTION  
M7423  
Fig. 3. Feature locations for T775A,B.  
LCD TEMPERATURE  
DISPLAY  
C \ F  
F/C SELECTION  
DIP SWITCHES FOR  
SENSOR SELECTION.  
PRESENT ON T775D  
ONLY  
PROGRAMMING  
KEYS  
SELECT  
SET  
ENTER  
SA SB  
SENSOR INPUT,  
TOD, AND 24VAC  
TERMINALS  
1
2
3
4
5
6
7
8
HOLE A  
SENSOR TOD  
A
24V SENSOR  
B
MOUNTING  
HOLES  
EARTH  
GROUND  
WIRE  
OUTPUT 2  
OUTPUT 1  
NC  
COM COM  
NO  
240V  
120V  
NC  
COM  
NO  
HOLE B  
NO  
COM  
NC  
NO  
COM  
NC  
LINE VOLTAGE  
INPUTS  
OUTPUT 3  
OUTPUT 4  
HOLE C  
NOTE: T775C TERMINAL BLOCK CONTAINS ONLY  
TERMINALS 1-6 AND HAS NO DIP SWITCHES  
RELAY OUTPUT STAGES  
FOR SENSOR SELECTION  
M7427  
Fig. 4. Feature locations for T775C,D.  
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T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
INSTALLATION  
When Installing this Product...  
T775  
1.  
Read these instructions carefully. Failure to follow them  
could damage the product or cause a hazardous  
condition.  
C \ F  
2.  
3.  
4.  
Check ratings given in instructions and on the product to  
ensure the product is suitable for your application.  
Installer must be a trained, experienced service  
technician.  
After installation is complete, check out product  
operation as provided in these instructions.  
SELECT  
SET  
ENTER  
GROUND  
SHIELD  
SA SB  
TO T775  
CABLE OR TO  
GROUNDING  
SCREW  
1
2
3
4
5
6
7
8
SHIELDED  
CABLE  
SENSOR TOD  
A
24V SENSOR  
B
CAUTION  
Electrical Shock or Equipment Damage Hazard.  
Can shock individuals or short equipment  
circuitry.  
OUTPUT 2  
OUTPUT 1  
NC  
Disconnect power supply before installation.  
120V  
NC  
COM  
NO  
COM COM  
NO  
240V  
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  
NO  
COM  
NC  
NO  
COM  
NC  
SHIELDED  
CABLE  
OUTPUT 3  
OUTPUT 4  
(
T775A,B) or Fig. 2 (T775C,D) as a guide.  
NOTE: DO NOT GROUND  
GROUNDING SCREW  
SHIELDED CABLE AT  
SENSOR END.  
Sensor Location  
The 193987GA Sensor can be located up to 1000 feet (304m)  
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. 7. The 193987GA is not a water tight or water  
resistant sensor. For wet applications, see the Accessories list  
in the Specifications section.  
SENSOR  
NOTE: TO MINIMIZE NOISE PICKUP, MAKE CONNECTION  
FROM SHIELDED CABLE AS CLOSE AS POSSIBLE  
TO SENSOR BODY.  
M7430  
Fig. 5. Using shielded cable (cable runs longer than 25 ft).  
NOTE: Use heat conductive compound in immersion wells.  
See Accessories in the Specifications section.  
Multiple sensors can be parallel-series wired to sense average  
temperatures in large spaces.  
CAUTION  
Can short equipment circuitry.  
Make sure that metal tube of sensor does not short  
against T terminals in wall-mounted case.  
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. 8.  
Electrical Shock Hazard.  
Sensor Mounting  
Sensors can be mounted on a wall or panel for sensing space  
temperature (Fig. 7), strapped to a pipe or inserted in a well  
COVER SENSOR  
LEADS WITH  
SENSOR PLACED  
IN WELL  
(
Fig. 6) for hot/cold water sensing, or taped to a standard cap  
HEAT CONDUCTIVE  
COMPOUND  
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.  
1
/2 NPT  
IMMERSION  
WELL  
M5249  
Fig. 6. Sensor inserted in immersion well.  
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63-2489—2  
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T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
WIRING  
T7047C1090  
WALLMOUNT SENSOR  
CASE (OPTIONAL)  
1
93987GA  
SENSOR  
CAUTION  
LEADWIRES  
TO T775  
Electrical Shock or Equipment Damage Hazard.  
Can shock individuals or short equipment  
circuitry.  
SCREW  
TERMINAL  
Disconnect power supply before installation.  
SCREW  
TERMINAL  
CAUTION  
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.  
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.  
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.  
CAUTION: POSITION SENSOR AWAY  
FROM SCREW TERMINALS.  
M8109C  
Fig. 7. Sensor mounted on wall.  
NOTE: Hole A should only be used for sensor, low-voltage  
and contact closure wiring.  
SENSORS  
When wiring the input power, only one source of power can be  
applied to the T775 (for example, 24 Vac or 120 Vac or  
2
1
40 Vac). Knockouts B and C can be used to gain access to  
20 Vac or 240 Vac input terminals and the load relay output  
terminals.  
See Fig. 11 through 14 for typical T775 wiring and applications.  
IMPORTANT  
Poor wiring practices can cause erratic temperature  
readings from the 193987GA Sensor. Avoid the  
following to ensure 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.  
•
•
•
•
•
•
TO T775 CONNECTIONS 1 AND 2 (SENSOR A)  
OR 7 AND 8 (SENSOR B).  
M7431  
Fig. 8. Parallel-series wiring of sensors.  
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).  
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T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
OPERATION  
Control Algorithm  
°F/°C Selection  
A single jumper plug controls °F/°C indication of the displayed  
temperature value. See Fig. 3 and 4 for the location of this  
jumper. The unit ships with the jumper installed in the °F mode.  
To operate the device in the °C mode, remove the jumper.  
Replacing the jumper reinstates the °F mode.  
On/Off Control  
The T775AC operate with one temperature input supplied by  
the remote sensor while T775B,D have two temperature  
inputs. The T775A,B,C,D are all capable of providing up to four  
stages of on/off control relay outputs. Each controller stage 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 programming keys.  
NOTES: If, upon removing the jumper plug, the device does  
not display °C:  
—
—
Remove power from the device.  
Replace power to the device.  
Heating Mode Operation  
DIP Switch Selections  
•
Relay outputs energize at the temperature setpoint minus  
the differential value.  
On the T775B,D, DIP switches are provided for assignment of  
each relay output stage to its operating sensor. If an individual  
switch is depressed to the right—toward its corresponding load  
number (1 through 4 on DIP switch)—Sensor B is the  
controlling sensor for that output stage. If an individual switch  
is depressed to the left, Sensor A is the controlling sensor for  
the output stage. An example of the switches and their  
corresponding positioning is shown in Fig. 9.  
•
Relay outputs de-energize at the temperature setpoint  
value.  
Cooling Mode Operation  
•
Relay outputs energize at the temperature setpoint plus  
differential value.  
•
Relay outputs de-energize at the temperature setpoint  
value.  
SENSOR A SENSOR B  
SWITCH  
EXAMPLE  
Using a device with one input and one relay output, the  
corresponding load energizes at the following temperatures  
based on the initial settings:  
LOAD 1  
PWB  
•
•
Setpoint: 68°F  
Differential: 2°F  
LOAD 2  
SWITCH  
LOAD 1 IS CONTROLLED BY  
SENSOR A WHEN SWITCH IS  
DEPRESSED ON THE LEFT  
Outputs Energized  
Heating Mode: Stage One energizes at 66°F.  
PWB  
Cooling Mode: Stage One energizes at 70°F.  
A
B
LOAD 2 IS CONTROLLED BY  
SENSOR B WHEN SWITCH IS  
DEPRESSED ON THE RIGHT  
SIDE VIEW  
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.  
(
AS SHOWN)  
M3292  
Fig. 9. DIP switch settings for sensor selection.  
Device Setup  
1.  
Determine loads to be controlled and the operating mode  
heat or cool) and enter them in the Device Programming  
(
Worksheet (Table 2).  
Contact Closure Override Input  
Table 2. Device Programming Worksheet.  
The two-terminal input allows the user to override a relay-  
energized condition on all outputs. This is done using contact  
closure between terminal pins 3 and 4 (TOD). (See Fig. 3 and  
Load 1:  
SetPt 1  
Diff 1  
Load 2:  
On at  
Off at  
4
for location.) This can be achieved manually or by using an  
EMS controller or time clock with normally open contacts  
W7505 or S7005, for example).  
(
SetPt 2  
Diff 2  
On at  
Off at  
When this override is active:  
—
The display shows the number of stages that would be  
energized  
Load 3:  
—
—
The words STAGE ENERGIZED flash on the display.  
Energized stages de-energize until the override returns to  
inactive (Off).  
SetPt 3  
Diff 3  
On at  
Off at  
Load 4:  
SetPt 4  
Diff 4  
On at  
Off at  
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T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
Programming Keys  
The four programming keys are Select, Up and Down (arrows),  
and Enter:  
For example: Load 1: Compressor 1 (cool)  
Setpt 1  
Diff 1  
On at  
Off at  
•
Select: Sequentially prompts the user about what parameter  
is being displayed. After the last parameter value is viewed,  
pressing the Select key again displays the control values  
from the beginning of the display loop. The parameters are:  
2
.
For two sensor models (T775B), determine which loads  
will be controlled from sensor A or sensor B and enter on  
the worksheet.  
—
—
—
—
—
setpoint,  
differential,  
stage energized,  
heat or cool (operation mode),  
1,2,3,4 (indicating assigned stage).  
For example: Load 1: Compressor 1 (cool)—Sensor A  
•
•
Up and Down: Allow the displayed parameter to be  
increased or decreased. After pressing Select, a control  
value can be changed using these keys. Control values  
increase or decrease by 1°F or 1°C each time an arrow key  
is pressed.  
Setpt 1  
Diff 1  
On at  
Off at  
Enter: Places the new value in the microprocessor memory.  
3.  
Determine setpoint (Setpt) and switching differential  
Diff) for each load and enter on the worksheet.  
(
IMPORTANT  
Control values/operations are not placed in the micro-  
For example: Load 1: Compressor 1 (cool)—Sensor A  
processor memory until the Enter key is pressed.  
Setpt 1  
Diff 1  
78°F  
4°F  
On at  
Off at  
Press the Select and Enter keys at the same time to change  
the control algorithm from heating to cooling or from cooling to  
heating:  
—
Heating and cooling parameters are not displayed during  
normal Select key sequences.  
The only parameters displayed after pressing the Select  
and Enter keys at the same time are 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.  
The next stage of heat or cool assignment appears after  
pressing the Select key. When all stages are programmed,  
the display reverts to sensed temperature and load  
energized status.  
4.  
Refer to the Control Algorithm subsection of Operation  
section to calculate the load on and off temperatures.  
Enter them on the worksheet.  
—
NOTE: Remember that the on/off outputs are off at  
setpoint in both heating and cooling operating  
modes. When in cooling mode, the load turns  
off at setpoint plus the differential. When in  
heating mode, the load turns on at setpoint  
minus the differential.  
—
—
For example: Load 1: Compressor 1 (cool)—Sensor A  
NOTE: Control values and operation selection remain in the  
device memory even after the power is removed.  
Setpt 1  
Diff 1  
78°F  
4°F  
On at  
Off at  
82°F  
78°F  
Display  
Once power is applied or restored to the device, the display  
counts down from 210 until the display reads zero. During this  
time all previously energized outputs de-energize. This is  
intended to protect compressors in the event of a power failure.  
CAUTION  
The T775 will not allow the user to program for both  
heating and cooling loads to be energized at the  
same time.  
NOTE: To avoid viewing the entire countdown, press the  
Select key.  
If this situation results, cooling loads will be energized  
and heating loads will be prevented from 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.  
The LCD display now shows what it normally reads:  
—
—
—
load (sensed) temperature,  
stages energized,  
and, for two sensor devices, the sensor (Sensor A or  
Sensor B) being read.  
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.  
NOTE: At any time during programming, a 60 second pause  
between key presses reverts the display to indicate  
the sensed temperature and stage status.  
For two sensor applications, the user has three options for  
display of sensed temperature. The display can be configured  
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.  
to:  
—
—
—
lock onto continuous Sensor A,  
lock onto continuous Sensor B sensed temperature,  
alternate between Sensor A and Sensor B (at approximate  
five-second intervals).  
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T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
This selection is accomplished in the Select screen scrolling  
loop:  
8. Press Select to go to the next stage.  
9. Repeat steps 6 through 9 for additional stages.  
10. Press Select after setting the last stage to return to the  
display of the sensed temperature.  
1
.
To lock on to either sensor, use the Select key to scroll  
through the loop to the temperature prompt of interest.  
Stop at Sensor A or Sensor B sensed temperature point.  
When the loop is stopped at any other prompt, the dis-  
play alternates between Sensor A and Sensor B sensed  
temperatures.  
2.  
.
3
Programming Stage Control Values  
1
2
.
.
Press Select to display the current stage setpoint.  
Press Set (up arrow) to increase or Set (down arrow) to  
decrease to the desired setpoint.  
NOTE: Pressing the Select key at the end of the pro-  
gramming sequence configures the display for  
alternating temperature display.  
3
4
.
.
Press Enter to place the displayed value into memory.  
Press Select to display the current stage switching  
differential.  
5.  
Press Set (up arrow) to increase or Set (down arrow) to  
decrease the switching differential.  
Device Programming  
6
7
8
.
.
.
Press Enter to place the displayed value into memory.  
Repeat steps 1 through 6 to program an additional stage.  
To return to stage 1 parameters:  
a. T775A,C: Press Select two times.  
b. T775B,D: Press Select four times  
Default Values  
When power is initially applied to the T775, the control points  
will be at their default value set at the factory. See Table 3 for  
default values.  
9. Scroll through the programming loop a second time to  
confirm that the appropriate values were entered into  
memory by pressing Select.  
Table 3. Default Programming Values.  
10. For the T775A,C, skip to step 12.  
Setpoint (°F) Differential (°F) Operating Mode  
Stage 1 72  
Stage 2 70  
Stage 3 68  
Stage 4 66  
2
2
2
2
Heat  
Heat  
Heat  
Heat  
NOTE: The T775B and D have three display options for the  
sensed temperature:  
(
(
(
1) Sensor A only.  
2) Sensor B only.  
3) Alternating between Sensor A and Sensor B (at  
approximately five-second intervals).  
1
.
For the T775B and D, 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).  
Before programming the T775, verify that the °F/°C  
selection jumper is properly installed. The T775 ships  
from the factory with the jumper in the °F position. If °C is  
desired, remove the jumper.  
1
1. To change the T775B,D display option:  
a. Sensor A only: Press Select after viewing the final  
stage switching differential.  
2.  
b. Sensor B only: Press Select a second time.  
c. Alternate between A and B: Press Select a third time.  
2. 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.  
1
3.  
Apply power to the device. The device begins counting  
down from 210. This countdown sequence lasts for  
approximately 3-1/2 minutes.  
IMPORTANT  
NOTE: If, upon removing the jumper plug, the device  
does not display °C:  
1
. For the T775A and C only: After initial programming,  
altering the setpoints for stage 1 up or down results in  
a change in setpoints 2, 3, and 4 by the same number  
of degrees and in the same direction.  
(
a)Remove power from the device.  
(b)Replace power to the device.  
2. The control rejects any change to the stage 1 setpoint  
if it results in exceeding control limits (-40° to +220°F  
4
5
.
.
Press Select to override the time delay.  
Press Select and Enter keys simultaneously to begin  
programming the load operating mode (Heat or Cool).  
Press the Set (down arrow) to change to cooling. The  
Set (up arrow) changes back to heating.  
[
-40° to +104°C]) for subsequent stages. This allows  
easy sequential output staging modifications while  
keeping the margin intact between setpoints.  
6
.
.
7
Press Enter to program mode displayed into memory.  
9
63-2489—2  
href="
T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
CHECKOUT  
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.  
Error Messages  
There are seven error messages that can display in response  
to T775 software or hardware problems. The error Codes that  
can flash on the display are:  
Table 4. Temperature Offset Based on Wire Length.  
•
SF: Sensor Failure  
—
A flashing SF indicates an out-of-range or defective  
sensor. Make sure that the sensors are connected  
properly. For T775A,C all loads de-energize when this  
error message flashes.  
For the T775B,D the loads controlled by the out-of-  
range sensor de-energize. The display flashes 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) operate normally. Only the  
load(s) controlled by the defective, out-of-range, or  
unconnected sensor de-energize.  
Sensor Wire Length  
to 399 ft  
400 to 599 ft  
Calibration Offset  
None required.  
0
1.0 degrees  
2.0 degrees  
3.0 degrees  
—
6
8
00 to 799 ft  
00 to 1000 ft  
After the controller is installed and wired, apply power. Make  
initial adjustments and desired settings:  
1.  
As shown in Fig. 10, 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  
NOTE: Sensor values below -40°F or above 220°F are  
out-of-range.  
(Fig. 10), the loads controlled by each sensor.  
2
.
.
Write the operating mode (heat or cool) for each stage in  
the Checkout Table (Fig. 10).  
Write the sensed temperature for each load on the  
Sensed Temp line.  
Write the differential for each load on the Differential line.  
Write the setpoint for each stage (Off temperature). Cal-  
culate the “On Temperature” for each stage.  
•
•
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.  
3
4
5
.
.
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.  
NOTE: “On temperature” is setpoint plus differential for  
cooling, and it is setpoint minus differential for  
heating.  
•
•
OF: Stray Interrupt Failure  
— An unused interrupt occurred. This error cannot be field  
repaired. Replace the device.  
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 (Fig. 10). As shown in the example, the display  
indicates, in the lower right corner, energized stages. If  
no stages are energized, the words “stage energized”  
will not appear.  
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 micro-  
NOTE: If the sensed temperature is between the On  
and Off temperatures, the load may either be  
energized or de-energized. Refer to the Control  
Algorithm section (in Operation) for further  
explanation.  
—
processor is defective. This error cannot be field  
repaired. Replace the device.  
AE: RAM error  
The internal Random Access Memory (RAM) of the  
—
8
.
.
If an error message flashes, refer to the description of  
these messages. If SF flashes:  
a. Check sensor connections.  
b. 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).  
If an error message other than SF flashes, the device  
cannot be field repaired. Replace the device.  
microprocessor is defective. This error cannot be field  
repaired. Replace the device.  
Setpoint Calibration  
To maintain temperature accuracy, use 18 AWG two-conductor  
sensor wires. If the length of the sensor wire exceeds 400 feet,  
recalibration will be necessary to maintain accuracy. Table 4  
shows the corresponding temperature offset to use for different  
9
6
3-2489—2  
10  
href="
T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
CHECKOUT EXAMPLE WITH SENSOR A = 68 AND SENSOR B = 73  
LOAD 1  
HEAT OR COOL (HEAT)  
MODE  
LOAD 2  
(HEAT)  
LOAD 3  
(HEAT)  
LOAD 4  
(HEAT)  
DIFFERENTIAL  
2
2
2
2
DESIGNATED  
SENSOR  
A
B
A
B
1
1
1
1
7
7
2
0
OFF  
7
6
0
8
CLOSED  
74 OFF  
76 OFF  
SETPOINT  
ON 2  
OPEN 2  
72 ON 2  
74 ON 2  
SENSED  
TEMPERATURE  
6
8
73  
68  
73  
LOAD 1  
IS ON  
LOAD 2  
IS OFF  
LOAD 3  
IS ON  
LOAD 4  
IS ON  
STAGE ENERGIZED 1 3 4  
SELECT  
SET  
ENTER  
NOTE: RELAYS ARE DE-ENERGIZED AT SET POINT  
CHECKOUT TABLE  
LOAD 1  
LOAD 2  
LOAD 3  
LOAD 4  
HEAT OR COOL  
MODE  
DIFFERENTIAL  
DESIGNATED  
SENSOR  
SETPOINT  
SENSED  
TEMPERATURE  
1
2
INDICATES LOAD STATUS WHEN SENSED TEMPERATURE REACHES SETPOINT.  
INDICATES LOAD STATUS WHEN SENSED TEMPERATURE REACHES SETPOINT  
MINUS DIFFERENTIAL (HEAT MODE).  
M7426A  
Fig. 10. Checkout Table and checkout example with Sensor A = 68°F and Sensor B = 73°F.  
11  
63-2489—2  
href="
T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
C \ F  
COOL MODE  
TEMPERATURE  
FALL  
3
RELAY 1 AND 2  
ENERGIZED  
SELECT  
SET  
ENTER  
DIFFERENTIAL  
2
SA SB  
SETPOINT 2  
RELAY 1 ENERGIZED  
NULL  
2
DIFFERENTIAL  
1
1
2
3
4
5
6
7
8
L1  
SENSOR A  
SENSOR TOD  
A
24V  
TEMPERATURE  
RISE  
(
HOT)  
2
SETPOINT 1  
2
4 VAC  
1
L2  
HEAT MODE  
TEMPERATURE  
FALL  
NULL  
SETPOINT 1  
OUTPUT 2  
OUTPUT 1  
NC  
DIFFERENTIAL  
1
120V  
NC  
COM  
NO  
LOAD 2  
COM COM  
240V  
RELAY 1 ENERGIZED  
NO  
SETPOINT 2  
LOAD 1  
DIFFERENTIAL  
2
RELAY 1 AND 2  
ENERGIZED  
TEMPERATURE  
RISE  
1
2
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.  
FOR T775B,D: CONNECT SENSOR B TO PINS 7 AND 8.  
M7421A  
DIP SWITCHES FOR SENSOR SELECTION. PRESENT OF T775B,D ONLY.  
Fig. 11. Two-stage control, 24 Vac input, 24 Vac load.  
6
3-2489—2  
12  
href="
T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
1
20 VAC INPUT; 120 VAC LOADS  
C \ F  
3
SELECT  
SET  
ENTER  
SA SB  
2
1
2
3
4
5
6
7
8
SENSOR A  
SENSOR TOD  
A
24V  
2
OUTPUT 2  
OUTPUT 1  
NC  
120V  
NC  
COM  
NO  
COM COM  
NO  
240V  
WHT  
1
1
20 VAC  
BLK  
COOL MODE  
TEMPERATURE  
FALL  
LOAD1  
LOAD 2  
RELAY 1 AND 2  
ENERGIZED  
DIFFERENTIAL 2  
SETPOINT 2  
2
40 VAC INPUT; 240 VAC LOADS  
RELAY 1 ENERGIZED  
NULL  
C \ F  
3
DIFFERENTIAL 1  
SETPOINT 1  
TEMPERATURE  
RISE  
SELECT  
SET  
ENTER  
TEMPERATURE  
FALL  
SA SB  
HEAT MODE  
NULL  
SETPOINT 1  
DIFFERENTIAL 1  
2
1
2
3
4
5
6
7
8
SENSOR A  
SENSOR TOD  
A
24V  
RELAY 1 ENERGIZED  
2
SETPOINT 2  
DIFFERENTIAL 2  
RELAY 1 AND 2  
ENERGIZED  
OUTPUT 2  
OUTPUT 1  
NC  
120V  
NC  
COM  
NO  
TEMPERATURE  
RISE  
COM COM  
NO  
240V  
RED  
BLK  
2
40 VAC  
1
LOAD1  
LOAD 2  
1
2
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.  
FOR T775B,D: CONNECT SENSOR B TO PINS 7 AND 8.  
DIP SWITCHES FOR SENSOR SELECTION. PRESENT OF T775B,D ONLY.  
M7422A  
Fig. 12. Two-stage control, 120 or 240 Vac input; 120 or 240 Vac load.  
13  
63-2489—2  
href="
T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
1
20 VAC INPUT; 120 VAC LOADS  
C \ F  
3
SELECT  
SET  
ENTER  
SA SB  
COOL MODE  
TEMPERATURE  
FALL  
1
2
3
4
5
6
7
8
2
SENSOR TOD  
A
24V SENSOR  
RELAY 1,2,3 AND 4  
ENERGIZED  
SENSOR A  
B
2
DIFFERENTIAL 4  
SETPOINT 4  
RELAY 1,2 AND 3  
ENERGIZED  
OUTPUT 2  
OUTPUT 1  
NC 120V  
COM COM  
NO 240V  
NC  
COM  
NO  
DIFFERENTIAL 3  
SETPOINT 3  
RELAY 1 AND 2  
ENERGIZED  
WHT  
NO  
COM  
NC  
NO  
COM  
NC  
DIFFERENTIAL 2  
SETPOINT 2  
120 VAC  
1
BLK  
OUTPUT 3  
OUTPUT 4  
RELAY 1 ENERGIZED  
DIFFERENTIAL 1  
SETPOINT 1  
TEMPERATURE  
RISE  
LOAD 4  
LOAD 3  
LOAD 2  
LOAD 1  
NULL  
2
40 VAC INPUT; 240 VAC LOADS  
C \ F  
HEAT MODE  
3
TEMPERATURE  
FALL  
NULL  
SETPOINT 1  
SELECT  
SET  
ENTER  
DIFFERENTIAL 1  
SA SB  
RELAY 1 ENERGIZED  
SETPOINT 2  
DIFFERENTIAL 2  
1
2
3
4
5
6
7
8
2
SENSOR TOD  
A
24V SENSOR  
RELAY 1 AND 2  
ENERGIZED  
SENSOR A  
B
2
SETPOINT 3  
DIFFERENTIAL 3  
RELAY 1,2 AND 3  
ENERGIZED  
OUTPUT 2  
OUTPUT 1  
SETPOINT 4  
NC 120V  
COM COM  
NO 240V  
NC  
COM  
NO  
DIFFERENTIAL 4  
RED  
RELAY 1 ,2,3 AND 4  
ENERGIZED  
NO  
COM  
NC  
NO  
COM  
NC  
TEMPERATURE  
RISE  
240 VAC  
1
BLK  
OUTPUT 3  
OUTPUT 4  
T775A  
LOAD 4  
LOAD 3  
LOAD 2  
LOAD 1  
1
2
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.  
FOR T775B,D: CONNECT SENSOR B TO PINS 7 AND 8.  
DIP SWITCHES FOR SENSOR SELECTION. PRESENT OF T775B,D ONLY.  
M7424A  
Fig. 13. Four stage control, 120 or 240 Vac input, 120 or 240 Vac load.  
6
3-2489—2  
14  
href="
T775A,B,C,D REMOTE TEMPERATURE CONTROLLER  
C \ F  
3
SELECT  
SET  
ENTER  
SA SB  
2
1
2
3
4
5
6
7
8
L1  
SENSOR A  
SENSOR TOD  
A
24V SENSOR  
(
HOT)  
B
2
2
4 VAC  
1
L2  
OUTPUT 2  
OUTPUT 1  
NC 120V  
COM COM  
NO 240V  
LOAD 3  
LOAD 1  
NC  
COM  
NO  
LOAD 4  
LOAD 2  
NO  
COM  
NC  
NO  
COM  
NC  
OUTPUT 3  
OUTPUT 4  
COOL MODE  
HEAT MODE  
TEMPERATURE  
FALL  
NULL  
RELAY 1,2 AND 3  
ENERGIZED  
SETPOINT 1  
TEMPERATURE  
FALL  
DIFFERENTIAL 1  
DIFFERENTIAL 3  
SETPOINT 3  
RELAY 1 ENERGIZED  
RELAY 1 AND 2  
ENERGIZED  
SETPOINT 2  
DIFFERENTIAL 2  
DIFFERENTIAL 2  
SETPOINT 2  
RELAY 1 AND 2  
ENERGIZED  
RELAY 1 ENERGIZED  
SETPOINT 3  
DIFFERENTIAL 3  
DIFFERENTIAL 1  
SETPOINT 1  
TEMPERATURE  
RISE  
RELAY 1,2 AND 3  
ENERGIZED  
TEMPERATURE  
RISE  
NULL  
NOTE: FOR THERMOSTAT APPLICATIONS, CONNECT CONTACT NO OF COOLING STAGE TO Y1 (AND SECOND STAGE TO Y2)  
CONNECT CONTACT NO OF HEATING STAGE TO W1 (AND SECOND STAGE TO W2).  
1
2
3
POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.  
FOR T775B,D: CONNECT SENSOR B TO PINS 7 AND 8.  
DIP SWITCHES FOR SENSOR SELECTION. PRESENT OF T775B,D ONLY.  
M7425A  
Fig. 14. Four-stage control, 24 Vac input; 24 Vac load.  
15  
63-2489—2  
href="
Automation and Control Solutions  
Honeywell International Inc.  
Honeywell Limited-Honeywell Limitée  
35 Dynamic Drive  
1
985 Douglas Drive North  
Golden Valley, MN 55422  
customer.honeywell.com  
Scarborough, Ontario M1V 4Z9  
®
©
U.S. Registered Trademark  
2005 Honeywell International Inc.  
6
3-2489—2 B.B. Rev. 07-05