Honeywell T6570, T8570 Series Digital Fan-Coil Thermostats
Product Data
Application
The T6570 Series Digital Fan-Coil thermostats provide line voltage on/off control for fans, valves, compressors, or auxiliary electric heaters in fan-coil and small air-conditioner applications. The T8570 Series provides low voltage control for these functions. Models are available for control of single-stage air-conditioners and various fan-coil units, including 2-pipe, 2-pipe with manual heat/cool changeover, 4-pipe with manual heat/cool changeover, and 4-pipe with automatic heat/cool changeover.
All models are suitable for multiple applications. Changes in output wiring and external links between wiring terminals can configure the thermostat for the appropriate application. The fan can also be controlled from the thermostat. In some cases, it is wired to run continuously and can be switched off with the On/Off switch. Other models can be installed with the fan running continuously or cycling with the thermostat. Compressors and auxiliary electric heaters can be controlled using a relay or contactor controlled by the thermostat.
Features
- Simple user interface.
- Attractive modern styling ideal for offices or hotels.
- Digital display of ambient temperature, with user-activated temperature display.
- Digital display shows mode icons when cooling or heating relays operate, or when energy savings mode is active.
- Push button setpoint adjustment.
- Switches allow manual control of system operation and fan speed.
- Energy savings mode: External energy savings input from time switch, occupancy sensors, or hotel cardkey overrides comfort setpoint with setback heating or cooling setpoint.
- Energy savings input is configurable for normally open or normally closed.
- Proportional plus integral (P+I) control algorithm for precision temperature regulation.
- Mounts directly onto wall or standard junction box or vertical junction box with an optional adapter plate.
- Installer setup mode allows changes of operating parameters.
- Selectable °C or °F display.
- Adjustable deadband (on some models) for heat and cool control.
- Selectable energy savings setup cooling and setback heating setpoints.
- Adjustable maximum heating and minimum cooling setpoint limits.
- Adjustable minimum relay off-times (heating or cooling) for compressor short-cycle protection.
- EEPROM permanently retains user settings during power loss (no batteries required).
- Capability to display temperature sensor failure for easier troubleshooting.
- Optional remote sensor (T8575D only).
Specifications
Table 1. Specifications
| Models | Voltage | Applications | Features | Switches | Control | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2-Pipe Fan Coil | 4-Pipe Fan Coil | Number of Relays | Energy Savings Input | Fan Auto | Changeover Auto | Remote Sensor (SPST) | On/Off (SP3T) | 3-Speed Fan | Heat/Cool | Wiring Diagram | ||
| T6574B | 120V, 208~277V, 50 - 60 Hz | •² | 1 | • | • | • | • | • | • | Fig. 6 | ||
| T6575B | •¹ | 1 | • | • | • | • | • | • | Fig. 7 | |||
| T6575C | 2 | • | • | • | • | • | • | Fig. 8 | ||||
| T6575D | 2 | • | • | • | • | • | • | Fig. 9 | ||||
| T8574B | 24V, 50 - 60 Hz | •² | 1 | • | • | • | • | • | • | Fig. 10, 13 | ||
| T8575B | •¹ | 1 | • | • | • | • | • | • | Fig. 11, 13 | |||
| T8575C | 2 | • | • | • | • | • | • | Fig. 12, 13 | ||||
| T8575D | 2 | • | • | • | •⁴ | • | • | Fig. 15, 16 | ||||
¹ Heating application
² Cooling application
³ 2-pipe system with external aquastat.
⁴ Optional accessory.
General Specifications
- Setpoint Range: 10°C to 30°C (50°F to 90°F).
- Supply Voltages: 24 (NEMA - rated transformer), 120, 230, 277 Vac (±10%), 50/60 Hz (depending on model selected), 0.5 A.
- Ambient Ratings:
- Temperature: Operating Range: 5°C to 45°C (41°F to 113°F). Shipping and Storage Range: -20°C to 55°C (-4°F to 131°F).
- Humidity Range: 5 to 95% RH, non-condensing at 26°C (79°F).
- Thermostat Output: 1spdt or 2 spst relay outputs (depending on model).
- Enclosure: Plastic (cover, base, and wallplate).
- Control Performance: On/Off control with P+I algorithm gives typical control to 0.75°C (1.5°F) at 22°C (72°F) and 50% duty cycle.
- Junction Box Mounting: Direct mounting on single gang NEMA 2" x 4" surface mount electrical box, or on 4" x 4" box with optional 272878 adapter plate.
- Wiring: 11 terminals; screw-in terminals capable of accepting up to 2 x 18 AWG, 1 x 14 AWG, or 1.5 mm² wires. Some terminals pre-fitted with color-coded flyleads.
Ordering Information
When purchasing replacement and modernization products, refer to the TRADELINE® Catalog or price sheets for complete ordering numbers from your TRADELINE® wholesaler or distributor.
For additional questions, information, or comments, please write or phone:
- Your local Honeywell Automation and Control Products Sales Office (check white pages of your phone directory).
- Honeywell Customer Care, 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 are located in all principal cities worldwide. Manufacturing occurs in Australia, Canada, Finland, France, Germany, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.
Electrical Rating
Table 2. Electrical Rating (50-60 Hz)
| 24V | 120V | 208V | 230V | 277V | |
|---|---|---|---|---|---|
| Amps (Resistive) | 3.8 | 3.8 | 3.8 | 3.8 | 3.8 |
| Full Load Inductive | 3.0 | 3.0¹ | 3.0 | 3.0 | 3.0 |
| Pilot Duty | 100 VA | ||||
¹ Equivalent to NEMA 1/8 horsepower rating; allowable load must be determined by adding nameplate full load and locked rotor rating of all loads.
Operational Life & Switches
- Minimum Operational Life (at maximum load): Thermostat contacts (at 120 Vac): 100,000 cycles
- Manual Switches: 10,000 operations.
- Energy Savings Input: 24 Vdc dry contact, maximum resistance of 1000 ohms. (See 'Caution' on page 3).
- Protection Class: IP30.
- Approvals: CSA Certified C/US LR158158 for Canada and the U.S.A. Meets CE requirements.
Accessories
- Adapter plate for mounting on single- or double-gang NEMA-standard vertical switch box: 272878 (line voltage models, 24V 2000 series), 272881 (24 V models, 1000 series).
- T8109: Remote temperature sensor for T8575D.
- W6380: Fan switching center for T8574/T8575 products.
Installation
When Installing this Product...
- Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condition.
- Check the ratings given in the instructions and on the product to ensure suitability for your application.
- The installer must be a trained, experienced service technician.
- After installation, check product operation as provided in these instructions.
⚠️ CAUTION
Electrical Shock or Equipment Damage Hazard. Can shock individuals or short equipment circuitry. Disconnect power supply before installation.
ℹ️ IMPORTANT
T6570 Series are line voltage powered devices. All wiring must comply with national and local electrical codes, ordinances, and regulations. Provide disconnect means and overload protection as required.
T8570 Series thermostats must be powered by an Approved 24 Vac, Class 2 transformer (such as a W6380 Relay Control Center).
Location
The T6570, T8570 series thermostats are the temperature control element in a fan-coil or air-conditioning system. They must be located approximately 1.5m (5 ft.) above the floor in a position with good air circulation to sense room temperature. The optional T8109 sensor can be used to sense temperature in return air ductwork instead of at the thermostat.
ℹ️ IMPORTANT
Do not mount the device where it can be affected by:
- Drafts or dead spots behind doors or in corners.
- Hot or cold air from ducts.
- Radiant heat from the sun or appliances.
- Unheated (uncooled) areas such as an outside wall behind the thermostat.
- Concealed pipes or chimneys.
Mounting
Any T6570, T8570 series thermostat can be mounted directly on the wall on a 65x65mm junction box, or a 2"x4" horizontal junction box. An optional adapter plate is available for mounting on a 4"x4" or vertical junction box (See Fig. 2). Mounting screws are supplied for alternatives.
- Feed leadwires through the wiring access hole of the wallplate and adapter plate (if used).
- Attach supply wires using wire nuts (not provided) or screw terminals, as appropriate.
- Locate the wallplate in the horizontal mounting position. See Fig. 2 if using the vertical junction box adapter plate.
- Push leadwires into the electrical junction box and attach the wallplate to the box using machine screws provided in the appropriate mounting holes.
- Attach thermostat to wallplate:
- Locate the two center side holes on the back of the thermostat.
- Align the holes with the two wallplate side tabs.
- Press down firmly to snap the thermostat into place.
Diagram Description: Fig. 2. Mounting the vertical junction box adapter plate M17505 Optional adapter plate.
This figure illustrates the optional adapter plate (M17505) used for mounting the thermostat onto a vertical junction box. It shows how the plate attaches to the junction box and provides mounting points for the thermostat wallplate.
Removing the thermostat
⚠️ CAUTION
Equipment Damage Hazard. Improper removal can damage the thermostat. Carefully follow the thermostat removal directions.
If it is necessary to remove the thermostat from the wallplate (see Fig. 3):
- Use a screwdriver to pry the thermostat's left side away from the base.
- Use the screwdriver to pry the thermostat's right side away from the wallplate.
Diagram Description: Fig. 3. Removing the thermostat
This figure shows the process of removing the thermostat from its wallplate. It depicts using a screwdriver to gently pry the thermostat away from the wallplate, first on the left side and then on the right side.
Thoroughly check wiring to the wallplate before finally mounting the thermostat on the wall.
Operation
Control
PROPORTIONAL + INTEGRAL (P+I) CONTROL
Like a mechanical thermostat, the T6570, T8570 Series have On/Off control output. However, this output is regulated by a P+I algorithm, enabling the thermostat to control closer to setpoint than conventional thermostats. This results in performance where the space temperature is maintained within 0.75°C (1.5°F) of the setpoint, regardless of fan speed.
P+I action minimizes the difference between the temperature setpoint and the effective control point by adjusting the output on-time until the control point matches the setpoint. The on-time is based on a fixed cycle rate of 4 cycles/hour for cooling (8 cycles/hour for heating), and the proportional band is 1.6°C (2.9°F).
? NOTE: Integral action corrects temperature control errors of proportional-only control but is slower to react to large temperature or setpoint changes. These thermostats also feature optional built-in time delays for equipment protection, which can inhibit rapid response to large setpoint changes if active.
SINGLE-STAGE COOLING OR HEATING CONTROL (SEE FIG. 4)
In cooling mode, the user setpoint is positioned at the bottom of the Proportional Band, so the setpoint effectively becomes the temperature where cooling switches off. In heating mode, the user setpoint is positioned at the top of the Proportional Band, and this is the temperature where heating switches off.
? NOTE: This also applies to models with manual heat/cool changeover.
Diagram Description: Fig. 4. Single stage control.
These diagrams illustrate single-stage temperature control. The top graph shows cooling control, where the cooling switches off at the user setpoint, which is at the lower edge of the proportional band. The bottom graph shows heating control, where heating switches off at the user setpoint, which is at the upper edge of the proportional band. It also depicts how a change in user setpoint affects the control points and how a user setpoint change can be restricted by limits.
AUTOMATIC CHANGEOVER WITH ZERO ENERGY DEADBAND (SEE FIG. 5)
This type of control is available on auto-changeover models only. The user setpoint centers on the Zero Energy Deadband. The cooling switch-off point is positioned at the bottom end of the cooling proportional band, and the heating switch-off point is positioned at the top end of the heating proportional band. Zero Energy Deadband width is selectable in the Installer Setup mode.
EXAMPLE: Using a deadband of 2°C (4°F) and a user setpoint of 22°C (72°F), the effective heating setpoint is 21°C (70°F) and the effective cooling setpoint is 23°C (74°F). A change to the user setpoint causes both heating and cooling setpoints to change in parallel. This change is restricted to the minimum cooling setpoint or maximum heating setpoint limits set within the Installer Setup mode.
Diagram Description: Fig. 5. Sequence control with deadband.
This diagram illustrates temperature control with a deadband, typically for auto-changeover systems. The user setpoint is in the center of the deadband. Cooling switches off at the upper limit of the cooling proportional band (which is above the deadband), and heating switches off at the lower limit of the heating proportional band (which is below the deadband). The diagram shows how the user setpoint change affects both heating and cooling switch-off points.
OPERATING MODES
The thermostat has two main operating modes: Comfort and Energy Savings. It also has an OFF mode selected by the On/Off switch.
OFF MODE
When the system switch is set to Off, power is removed from the thermostat electronics and output terminals, and the display goes blank. The thermostat will reboot when power is restored with the On/Off switch.
? NOTE: This On/Off switch is a functional switch and should not be used as an isolating switch.
STARTUP
On first powering up, or after the On/Off switch has been set to On, the thermostat undergoes a startup and self-checking sequence. First, all LCD display segments illuminate to check the display. Next, a number appears indicating the software version. The final check is a sensor check. On completion of the startup sequence (approx. 2 seconds), the thermostat resumes normal control in either Comfort or Economy mode. On initial power-on, the temperature setpoint defaults are as shown in Table 3. The current setpoint is stored in EEPROM and retained if the thermostat is switched off and then on again.
Table 3. Power Up Default Setpoints
| 1 relay or heat cool changeover models | 2 relay + cool sequence models | |||
|---|---|---|---|---|
| °C Scale | °F Scale | °C Scale | °F Scale | |
| Setpoint Default | 22 | 73 | 22 | 73 |
| Cooling OFF point | — | — | 23 | 75 |
| Heating OFF point | — | — | 21 | 71 |
COMFORT MODE
This is the normal operating mode where the thermostat controls to the user-selected setpoint. On initial power-up, the user setpoint will return to the last known or default value. Control action is determined by default settings or installer-set parameters.
ENERGY SAVINGS MODE
Energy Savings mode is activated by a dry contact closure on the special Energy Management System (EMS) input from an occupancy detector, window contact, etc. If the signal via input terminals 10 and 11 calls for Energy Savings mode, the thermostat controls to user/installer-defined setback setpoints for increased energy savings. The display shows a $ symbol to indicate Energy Savings mode is active.
For example, if the user setpoint is 21°C (70°F) and the Energy Savings mode setpoint for cooling (unoccupied cooling setpoint) is set to 28°C (82°F), the thermostat controls to 28°C (82°F) when the input signal activates economy mode. There is no user override as long as the EMS signal is present. Default Energy Savings mode setpoints are shown in Table 4.
The Energy Savings mode input can be configured in the installer setup mode to be activated by either a short-circuit (default) or open-circuit signal.
User Programming Modes
Additional Switches
FAN SPEED SWITCH (SP3T LINE VOLTAGE)
Where supplied, the fan switch allows selection of three settings: low, medium, or high. ? NOTE: The installer should select Constant Fan mode if the fan motor is a type that does not start reliably at low speed.
SYSTEM HEAT/COOL SWITCH (SPST LOW VOLTAGE)
Where supplied, this switch signals the microprocessor to operate the relays in either heating or cooling mode. In heating mode, the cooling relay is disabled. In cooling mode, the heating relay is disabled.
TEMPERATURE (COMFORT) SETPOINT
The temperature setpoint can be adjusted between 10°C and 30°C in steps of 0.5°C using the [UP] and [DOWN] keys. If °F is set in the installer setup mode, the range is 50°F to 90°F, adjustable in 1°F steps.
DISPLAY
The measured room temperature is normally displayed (unless rt = 0 in installer setup mode). The first press of the [UP] or [DOWN] keys switches to display the user setpoint. If no key is pressed for 5 seconds, the display returns to showing the room temperature.
When the cooling relay is closed, this is indicated by a ❄️ symbol. Closure of the heating relay is indicated by a ? symbol.
If there is a wiring problem or the room temperature is less than 5°C (40°F) or over 38°C (100°F), the display shows an SF (Sensor Failure) warning. If this warning is not due to a wiring problem, it will disappear once the remote sensor or thermostat comes within the 4.5 to 37.8°C (40 to 100°F) range. If the SF warning is due to a faulty remote sensor connection, the thermostat will not transfer measurement to the internal sensor. To resolve this, power down the thermostat, disconnect or fix the remote sensor connection, and then re-power the thermostat.
Installer Setup Mode
The thermostat allows many operating parameters to be adjusted via an Installer Setup Mode. Each parameter has a two-letter identifier code shown on the display during the programming sequence. A description of these is shown in Table 5.
PROGRAMMING PARAMETERS
The installer setup mode is accessed by reducing the setpoint to 10°C (50°F), waiting 3 seconds (or until room temperature is displayed), and then pressing the [UP] and [DOWN] keys simultaneously for 3 seconds. If the Minimum Cooling Setpoint was previously increased above 10°C (50°F), reduce the setpoint to the new value before pressing the buttons.
The first parameter identifier is displayed, and its value can be changed by pressing the [UP] key. The first press shows the default value; subsequent presses alter the value, wrapping around. Press [DOWN] to select the parameter value and move to the next parameter. After the final parameter, a further press of [DOWN] exits programming mode.
PARAMETER VALUES
Each parameter has a default value used on first power-up. This can be changed in Installer Setup Mode and is stored in EEPROM, so it is not lost on power interruption. To restore default values, change the temperature scale (tS) from °C to °F (or vice versa) and back again.
PROGRAMMING EXAMPLE
To enter the installer setup mode:
- Press to change the temperature setpoint to 10°C (50°F).
- Wait 3 seconds, or until the room temperature is displayed.
- Press and hold together until [tS] is displayed.
- Press once to show the default Temperature Scale value. Continue pressing to cycle through all possible values for this parameter.
- When the desired value is displayed, press once to select it. This moves to the next parameter, whose identifier will be displayed.
- Use [UP] and [DOWN] to move between parameters and alter values.
- When the last parameter [rt] is selected, a final press of [DOWN] returns the display to normal operating mode.
Table 5. Thermostat Parameter Options
| Parameter | ID | Description | °C Scale | °F Scale | ||
|---|---|---|---|---|---|---|
| Default | Values | Default | Values | |||
| Temperature Scale | tS | Allows selection of either °C or °F scale | Yes | — | No | — |
| Dead Band | db | Setting deadband (Zero Energy Band) | 2 | 2, 3, 4 | 4 | 3, 4, 5 |
| Heat or Cool Operating Mode | OP | Setting operating mode on single relay, non-changeover models, to either Heat or Cool | 0: cool 1: heat | 0: cool 1: heat | ||
| Unoccupied Cooling Setpoint | uC | Program unoccupied cooling setpoint for energy savings. | 25 | 25 to 30 | 77 | 77 to 90 |
| Unoccupied Heating Setpoint | uH | Program unoccupied heating setpoint for energy savings | 18 | 10 to 18 | 65 | 50 to 65 |
| Minimum Cooling Off Time | CO | Setting cooling off-time for short cycle prevention. | 0 | 0, 3, 4, 5 | 0 | 0, 3, 4, 5 |
| Minimum Heating Off Time | HO | Setting heating off-time for short cycle prevention. | 0 | 0, 3, 4, 5 | 0 | 0, 3, 4, 5 |
| Minimum Cooling Setpoint (Low Limit) | CL | Sets the minimum allowable cooling setpoint. | 10 | 10 to 30 | 50 | 50 to 90 |
| Maximum Heating Setpoint (High Limit) | HL | Sets the maximum allowable heating setpoint. | 30 | 10 to 30 | 90 | 50 to 90 |
| Energy Savings Configuration | ES | Activate energy savings mode by a choice of either contact closure or contact opening. | 1 | 1: normally open 0: normally closed | 1 | 1: normally open 0: normally closed |
| Display of Room Temperature | rt | Allows installer to restrict temperature display to set point only. With this parameter, the unit will only display the set point temperature. Useful where setpoint limits (HL and CL) will affect control performance and Room Temperature display will disagree with user setpoint. | 1 | 1: room temp. 0: setpoint only | 1 | 1: room temp. 0: setpoint only |
Wiring
Table 6. Leadwire Color Code (if fitted)
| Terminal | Color | Use |
|---|---|---|
| 1 | Black (BK) | L1 (Hot) |
| 2 | White (WH) | L2 (N) |
| 3 | Orange (OR) | Heat |
| 4 | Yellow (YL) | Cool |
| 5 | Gray (GY) | Damper |
| 6 | Violet (VI) | Fan Common |
| 7 | Red (RD) | Fan Low |
| 8 | Blue (BU) | Fan Medium |
| 9 | Brown (BN) | Fan High |
| 10 | — | |
| 11 | — | Energy Mgt. System |
Wiring Diagrams
The following figures illustrate various wiring configurations for the T6570 and T8570 series thermostats. Always ensure power is disconnected before wiring.
- Fig. 6. Wiring 2-pipe cool-only thermostat with fan On/Auto switch. This diagram shows connections for a 2-pipe system used exclusively for cooling, with a fan On/Auto switch.
- Fig. 7. Wiring 2-pipe heat-only thermostat with fan On/Auto switch. This diagram illustrates wiring for a 2-pipe system used exclusively for heating, featuring a fan On/Auto switch.
- Fig. 8. Wiring 2-pipe seasonal heat/cool changeover with external aquastat, fan On/Auto switch. This diagram depicts a 2-pipe system with manual heat/cool changeover, an external aquastat, and a fan On/Auto switch.
- Fig. 9. Wiring 2-pipe heat/cool with manual heat/cool changeover switch, continuous fan or cycled fan. This diagram shows a 2-pipe system with manual heat/cool changeover and options for continuous or cycled fan operation.
- Fig. 10. Wiring 4-pipe, heat/cool with manual heat/cool changeover switch, continuous fan. This diagram illustrates a 4-pipe system with manual heat/cool changeover and continuous fan operation.
- Fig. 11. Wiring 4-pipe, auto heat/cool changeover. This diagram shows a 4-pipe system with automatic heat/cool changeover.
- Fig. 12. Wiring 4-pipe, auto heat/cool changeover, with fan On/Auto switch. This diagram depicts a 4-pipe system with automatic heat/cool changeover and a fan On/Auto switch.
- Fig. 13. Wiring 4-pipe, heat/cool with manual heat/cool changeover switch, cycled fan, using external relay. This diagram shows a 4-pipe system with manual heat/cool changeover, cycled fan, and the use of an external relay.
- Fig. 14. W6380 wiring diagram. This diagram illustrates the schematic for the Honeywell W6380 Fan-Relay Control Center, which provides 24 Vac power and wiring terminations for valve, relay, and contactor loads.
- Fig. 15. Wiring 2-pipe, 24V cool-only thermostat with fan On/Auto switch. This diagram shows wiring for a 24V low-voltage, 2-pipe cool-only thermostat with a fan On/Auto switch.
- Fig. 16. Wiring 2-pipe 24V heat thermostat with fan On/Auto switch. This diagram illustrates wiring for a 24V low-voltage, 2-pipe heat-only thermostat with a fan On/Auto switch.
- Fig. 17. Wiring 2-pipe heat/cool with manual heat/cool changeover switch, continuous or cycled fan. This diagram shows wiring for a 24V low-voltage, 2-pipe heat/cool thermostat with manual changeover and options for continuous or cycled fan.
- Fig. 18. Wiring 4-pipe 24V heat/cool with manual heat/cool changeover switch, continuous fan. This diagram depicts wiring for a 24V low-voltage, 4-pipe heat/cool thermostat with manual changeover and continuous fan.
- Fig. 19. Wiring 4-pipe 24V auto heat/cool changeover with continuous fan. This diagram shows wiring for a 24V low-voltage, 4-pipe auto heat/cool changeover thermostat with continuous fan.
- Fig. 20. Wiring 4-pipe 24V auto heat/cool changeover thermostat with fan On/Auto switch. This diagram illustrates wiring for a 24V low-voltage, 4-pipe auto heat/cool changeover thermostat with a fan On/Auto switch.
Important Wiring Notes:
- For power supply, provide disconnect means and overload protection as required. Special service CO/ALR solderless connectors must be used when connecting with aluminum conductors, otherwise a fire hazard may result.
- Jumper terminals are often used for specific configurations (e.g., fan operation modes, auto/on fan, continuous/cycled fan). Refer to individual diagram notes for details.
- Terminal 5 may be used to operate a 24 Vac ventilation damper actuator.
- EMS function is typically disabled when using certain configurations or external relays.
Wiring Remote Sensor
The T8109 is an optional remote sensor that can be used as an alternative to the internal sensor of the T8575D. The T8109 remote sensor plugs into the J2 header in the back of the thermostat. On power-up, the T8575D will look for a T8109. If one is connected, it will use this sensor for control. If not, it will use the internal sensor.
To change the sensor source, turn off the thermostat power, disconnect the current sensor source, connect the new sensor source, and re-power the thermostat. On power-up, the T8575D will find the new sensor source and use it for control.
To extend the sensor cable, use only shielded cable (e.g., Beldfoil® 18 AWG) up to a maximum of 70 feet (20m). The sensor connections are polarity sensitive; connect the shielded wire to the sensor's blue wire, as shown in Fig. 21.
Diagram Description: Fig. 21. Wiring optional remote sensor for the T8575D model.
This diagram shows how to connect the optional T8109 remote temperature sensor to the T8575D thermostat via the J2 header. It highlights the polarity sensitivity and the use of shielded cable, indicating which wire connects to the blue sensor wire.
Cautions
⚠️ CAUTION
Equipment Damage Hazard. Operation at low temperatures can cause fan coil damage. This thermostat is not a safety device. Do not use it where the space temperature is outside the device operating range. A display of SF indicates a space temperature outside the thermostat operating range (5°C to 45°C). With SF displayed, the thermostat ceases to operate.
⚠️ CAUTION
Equipment Damage Hazard. Improper operation can cause compressor damage. Do not operate cooling if outdoor temperature is below 50°F (10°C). Refer to manufacturer recommendations. To avoid compressor damage, allow the compressor to remain off for five minutes before restarting.
