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1
Commercial T775 Series 2000
Stand-Alone Temperature
and Humidity Controllers
User Manual
By Piotr Blaut IP2
This technical report reviews the T775 humidity and temperature Stand-Alone Controller
manufactured by Honeywell.
1Safety:
The T775U it is not a limit or safety control device - is the operating control device.
Used in applications that requiring safety or limit controls - a separate safety or limit control
device is required.
10/20/2013

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Contents
1.0 Principle of Operation of T775U Controller............................................ 1
1.1 Principles of control of temperature and humidity. ................................... 1
1.2 T775U Controller ........................................................................ 2
2.0 End-User Instructions. ..................................................................... 3
2.1 Features.................................................................................. 3
2.2 T775U2006 and T775U2016 N Universal Models ........................................ 6
3.0 Outline of Installation and Connectivity .................................................. 6
3.1 Installation Instructions ................................................................. 6
3.2 General Mounting Instructions .......................................................... 6
3.21 Controller Mounting.................................................................. 7
3.22 Humidity Sensor Mounting and Location ............................................ 7
3.23 Temperature Sensor(s) Mounting and Location..................................... 8
3.24 Wiring Connections Access. ......................................................... 8
3.25 Controller Wiring .................................................................... 8
3.26 Humidity Sensor Wiring............................................................. 10
3.27 Temperature Sensor Wiring ........................................................ 10
3.28 CHECKOUT .......................................................................... 11
4.0 Setup ...................................................................................... 11
4.1 Humidity Sensor Calibration......................................................... 11
4.2 Temperature Sensor Calibration..................................................... 11
4.3 Interface Overview................................................................... 11
4.4 Programming the T775U. ............................................................ 11
References .................................................................................... 12
Figures and tables............................................................................. 12
Appendix ...................................................................................... 13
A.1.0 T775U Universal Model Specifications............................................... 13

3. 1
1.0 Principle of Operation of T775U Controller
1.1 Principles of control of temperature and humidity.
Commercial systems requires a high control accuracy of temperature and humidity.
The environment to be conditioned is controlled at a targeted dew point
temperature and then reheated to a specified air temperature. Maintaining a
constant dew point and air temperature will produce a very constant relative
humidity [1].
Figure 1 Principles of control the temperature and humidity
A. The air is directed through a water spray area with a closely controlled
temperature. The water spray is adjusted to maintain the dew point
temperature of the targeted condition. As the air passes through the water
spray, it is cooled down to the temperature of the water and approaches
saturation.
B. The air leaves the spray chamber through a mist eliminator and is mixed with
air that has by-passed the spray area.
C. The air passes over an electric heater (to warm the air back to the desired
temperature).
The temperature of the water spray is automatically adjusted by the T775U
Controller by the feedback from a RH sensor in the controlled space.

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Also the power of heating of the electric heater is adjusted by the T775U
Controller by the feedback from a temperature sensor in the controlled space.
1.2 T775U Controller
The Stand-Alone Controller uses a variety of sensors via an analogue input for
processing and analysis. T775U uses a PID controller algorithm to compute the
relevant output to control Humidity and Temperature. T775U can make all
decisions at the access point - the device is able to operate independently from
any other device or system[2].
The T775U has an easy setup for configuring control of temperature or humidity
with a range of inputs, such as:
 0-5 Vdc
 0-10 Vdc
 4-20 mA
Control humidity with % RH displayed, CO2 with ppm displayed, or control pressure
with psi, Pa, or kPa displayed. Outputs include two modulating and two relay
outputs that can each have their own set-point. The T775U offers complete
versatility in a single control[3].
T775U Universal Stand Alone Controller (see Fig.2) that controls pressure,
humidity, temperature or any control medium that inputs 1097 Ω PTC, 0-10 Vdc or
4-20 mA. [1].
Figure 2 Honeywell T775 Series 2000 Stand-Alone Controller
The T775U Controller is equipped with 2SPDT, 2 Analogue outputs and 2 x sensor inputs
and can be used for applications where electronic accuracy and remote sensing of
temperature, humidity or pressure are required [2].

5. 3
2.0 End-User Instructions.
2.1 Features.
 Graphical Interface
User-friendly Graphical Interface (see Fig.3) - easy and the intuitive programming
will save time [6].
 Protective Enclosures
Possible purchase the controllers with NEMA 4X enclosures - to protect them from
water and corrosion.
 Internal Time Clock Scheduler
The Setback and Disable Output options, controlled by the built-in scheduler or
digital input). Helps save energy during unoccupied times and gives more control of
the equipment without needing to purchase an additional time clock. Run times
can be displayed for the first 4 relay outputs.
 Modulating High Or Low Limit Control
To protect equipment from freezing or overheating, models have the ability to
adjust the control temperature at Sensor A to protect equipment at Sensor B. The
controller adjusts its modulating output to prevent exceeding the user-entered
High or Low limit for Sensor B
 Sensor Calibration
Calibrate input sensors up to +/-6°C for temperature and up to +/-10 % of range for
other sensors (e.g. pressure, humidity) to compensate for resistance drops in
longer sensor wire runs (see Fig.4).
Figure 3 T775U Controller Graphical Interface

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Figure 4 Sensor Calibration Setup on Display
 Built-in the keypad lockout
Figure 5 Keypad Lockout
 Independent Modulating Outputs
Up To Two Independent Modulating Outputs (see Fig. 6) [6] - each output can be
individually configured for 0-10 Vdc, 2-10 Vdc, 4-20 mA or Series 90.
Figure 6 Modulating Outputs Setup
 Sensor labels displayed on the Home screen
Descriptive labels for each sensor selected from a list can be memorized and
displayed on the screen.
Figure 7 Sensor labels displayed on the Display

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 All T775s can be powered with low or line voltage (24/120/240 Vac)
No need to add a separate transformer
 Configurable Minimum Off Time
Setting a minimum off time can protect equipment and reduce the need for a
separate time delay device (See Fig.8).
Figure 8 Minimum off Time Setting
Optional Configurable Integral and Derivative Times Standard on every device.
This feature provides pinpoint (PI or PID) control on modulating outputs set up.
The reaction times and behaviour can be adjusted to give more control. Anti-
integral wind-up is standard (See Fig.9).
Figure 9 PI or PID setup
 Displayed the Relay Runtime.
Quickly and easily check to see how many hours a stage has been running.
Reset to zero at any time
Figure 10 Relay Runtime on display

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2.2 T775U2006 and T775U2016 N Universal Models
Figure 11 T775U2006 and T775U2016 N Universal Models
3.0 Outline of Installation and Connectivity
 Failure to follow instructions given by manufacture guidelines could result in
damaged controllers or hazardous conditions.
 The manufacturer recommends that installation be provided by a trained,
experienced service technician.
 Following installation, product operation must be re-checked and verified
3.1 Installation Instructions
The order of the installation procedure:
A. Mounting
B. Wiring
C. Checkout
D. Interface overview and Programming
E. Setup
3.2 General Mounting Instructions
IMPORTANT
 The producer recommend to install the controller in environment free of acid
fumes or other deteriorating vapours that can attack the metal parts of the
controller circuit board.
 The controller should be installed in a place that allows clearance for wiring,
servicing, and removal.
 Poor wiring will cause erratic readings from the sensor. For proper operation, good
mechanical connections are necessary to both the sensor and the controller.

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3.21 Controller Mounting
The controller can be mounted on any convenient interior location by using the four
mounting holes provided on the back of the enclosure. The controller dimensions can be
checked in Fig. 12, [6].
The controller may be mounted in any orientation - however, installation follow the
orientation shown in Fig. 12 permits proper viewing of the LCD display and use of the
keypad.
3.22 Humidity Sensor Mounting and Location
Humidity Sensors (Sensor A only). The controller accepts 0-10 Vdc or 4-20 mA input with a
range of 0-100%. A range of sensors are available [7] and these may be mounted on a wall
or panel. During the installation the user is requested to follow the installation
instructions specific to the sensor used.
Figure 12 controller dimensions

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3.23 Temperature Sensor(s) Mounting and Location
Temperature sensors may be located up to a maximum of 304 metres from the T775U
controller. The sensors may be:
 mounted on a wall or panel for sensing space temperature
 strapped to a pipe
 inserted in an immersion well for hot or cold water sensing
 taped to a standard cap or bulb holder for duct air sensing.
The manufacturer recommends mounting sensors with the lead wires exiting the bottom of
the sensor to prevent moisture or condensation entering the sensor [6]. See the available
Temperature Sensors (Sensor A or B) to purchase separately[7].
3.24 Wiring Connections Access.
The two screws on the left side of the enclosure can be removed to gain access to the
wiring connections. It is important that one avoids damaging the fragile ribbon cables
connecting the keypad and LCD display to the controller circuit board [6].
3.25 Controller Wiring
Used during the installation - wiring must comply with specified on installation wiring
diagrams or with applicable electrical codes and ordinances. Controller wiring is
terminated to the screw terminal blocks located inside the device[6].
Access to the terminals can be gained through standard conduit knockouts (A through E -
See in Fig. 13) located around the enclosure:
• Knockouts A and B are designed for sensor and low-voltage wiring.
• Knockouts C, D and E are designed to gain access to the load relay output terminals and
120/240 Vac power wiring.
NOTE: Only one source of power can be applied to the T775U (24 Vac or 120 Vac or 240 Vac).
IMPORTANT:
 A 24 Vac power must not be used to power any external loads if 120 Vac or 240 Vac
is used to power the T775U.
 A separate earth ground is required.
 Electrostatic discharge can short equipment circuitry.
The wiring connection terminals are shown in Fig. 13 and are described in Table below
(See Fig. 14) [6].

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Figure 14 T775U wiring connection terminals [4]
Figure 13 T775U wiring connection terminals [8]

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3.26 Humidity Sensor Wiring
Sensors with a 0-5 Vdc, 0-10Vdc or 4-20mA input to the T775U must be wired to the Sensor
“A” terminal. Sensor B is used only as a temperature input. Sensors use standard AWG 18
unshielded wire. For cable runs greater than 25 feet, shielded cable is recommended [6].
For wiring details, see Fig. 15 (below).
Figure 15 Humidity Sensor Wiring [8]
3.27 Temperature Sensor Wiring
For wiring details, see Fig. 16 (below).
Figure 16 Temperature SensorWiring [8]

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3.28 CHECKOUT
All connections made at the controller terminals should be inspected and verified with the
installation wiring diagrams. In case the wiring changes are required - the power from the
controller must be cut off. The power connection should be double checked. The power
can be applied after the controller is mounted and wired [6].
4.0 Setup
Setup provides the ability to change the factory default settings for the temperature
sensors and outputs, to enable/disable reset control, and to enable/disable scheduling.
4.1 Humidity Sensor Calibration
A calibration parameter is available using Setup mode. The calibration range is +/- 10% of
the Min Value to Max Value range setup for the sensor. Examples of the Humidity Sensor
Calibration [8].
4.2 Temperature Sensor Calibration.
As wire length increases, resistance increases and thus the temperature reading increases.
If it necessary to calibrate the sensor input see "CALIBRATE (Sensor A or B)" [8].
4.3 Interface Overview.
The T775U controller uses an LCD panel and 6-button keypad to provide status information
and permit user input of the programming, setup, and scheduling parameters [9].
4.4 Programming the T775U.
The controller must be programmed before being placed into service. The Programming
process uses a hierarchical menu structure that is easy to use [9].

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References
[1] General Information Honeywell Humidity Controllers - Commercial
[2] Electronic Universal Controller General Information - Technical Information
[3] Product Data and Specifications-Series 2000 Electronic Stand-Alone Controllers
[4] Installation Materials-Series 2000 Electronic Stand-Alone Controller
[5] SPECIFICATION DATA Product Data and Specifications-Series 2000 Electronic Stand-
Alone Controllers
[6] Installation Instructions-Series 2000 Electronic Stand-Alone Controller
[7] Wiring. Sensors available to purchase separately.
[8] Setup. Calibration Humidity and Temperature Sensors Calibration Instructions and
Examples (page 17).
[9] Programming the T775U Controller(page 26).
Figures and tables
Figure 1 Principles of control the temperature and humidity................................ 1
Figure 2 Honeywell T775 Series 2000 Stand-Alone Controller ................................ 2
Figure 3 T775U Controller Graphical Interface ............................................... 3
Figure 4 Sensor Calibration Setup on Display ................................................. 4
Figure 5 Keypad Lockout....................................................................... 4
Figure 6 Modulating Outputs Setup............................................................ 4
Figure 7 Sensor labels displayed on the Display .............................................. 4
Figure 8 Minimum off Time Setting............................................................ 5
Figure 9 PI or PID setup........................................................................ 5
Figure 10 Relay Runtime on display ........................................................... 5
Figure 11 T775U2006 and T775U2016 N Universal Models .................................... 6
Figure 12 controller dimensions ............................................................... 7
Figure 14 T775U wiring connection terminals................................................. 9
Figure 13 T775U wiring connection terminals................................................. 9
Figure 15 Humidity Sensor Wiring ............................................................ 10
Figure 16 Temperature Sensor Wiring ........................................................... 10

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Appendix
A.1.0 T775U Universal Model Specifications
Power: 24, 120, or 240 Vac; 50/60 Hz. [3]
A separate earth ground is required for any power source.
Power Consumption:
• 8 VA maximum at 60 Hz
• 10 VA maximum at 50 Hz
Operating and Storage Temperature Ambient Rating:
• -40° to 52°C @ 50 Hz
• -40° to 60°C @ 60 Hz
Relative Humidity: 5% to 95% non-condensing
All T775 controllers are field-mountable in any orientation to either a panel or wall.
Digital Input (DI):
• 18 Vdc and 3.5 mA (for choosing external contact)
• Alternating Current (AC):
— 30 Vac RMS; 1.5 A steady 3 A inrush P.F. 0.45 NC
— 20 Vac RMS; 100 mA minimum load on NO and NC contacts
Direct Current (DC): 1 mA - at 100 mV DC minimum load NOTE: In applications requiring a gold
contact signal relay, an external signal relay or additional load resistor may be needed for the
digital output.
Relay Contact Output Ratings (N.O. and N.C.):
• 1/2 hp; 9.8 AFL, 58.8 ALR @ 120 Vac
• 1/2 hp; 4.9 AFL, 29.4 ALR @ 240 Vac
• 125 VA pilot duty @ 120/240 Vac
• 10A @ 24 Vac (resistive)
Modulating Outputs:
• 0-10 Vdc; drive a minimum of 2,000 Ohms
• 2-10 Vdc; drive a minimum of 2,000 Ohms
• 4-20 mA; drive a maximum of 600 Ohms
• Electronic Series 90; requires 340 Ohm resistor (included) across terminals R and W
• Floating
Sensed Temperature Limits:
Minimum -51° C / Maximum 132° C
High Set point Limit: An irreversible high limit set point can be configured to meet local code
requirements.
Sensed Temperature Accuracy:
• T775: 1°C @ ambient room temperature of 25° C.
• 50021579-001 and T775-SENS-WR: +/-.24° from -30° to 120° C
Set point Range: -40° to 120°C
Time Clock: Two settable time periods per day are standard on all models.

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Volatile Memory: The date and time settings are retained for 24 hours after a power outage.
After a power loss of more than 24 hours, the date and time settings may need to be re-entered.
All other settings are stored permanently [3].