Item specifics
Description
◆ Model
XH-W1209 Digital Thermostat Module
◆ Supply Voltage
DC 12V (5V/24V versions also available)
◆ Power Consumption
Standby ≤35mA, Relay ON ≤65mA
◆ Output Relay
10A (some versions rated 20A)
◆ Display
0.28-inch 3-digit 7-segment LED (Red/Blue options)
◆ Temperature Range
-50°C ~ 110°C
◆ Resolution
0.1°C (-9.9~99.9°C) / 1°C (other ranges)
◆ Sensor Type
NTC 10K 0.5% waterproof thermistor
◆ Sensor Cable Length
Approx. 50cm
◆ Cooling Mode (C)
Relay activates when measured temperature ≥ set point; deactivates when temperature ≤ set point - hysteresis
◆ Heating Mode (H)
Relay activates when measured temperature ≤ set point; deactivates when temperature ≥ set point + hysteresis
◆ Normal Display
Current real-time temperature
◆ LL Alarm
Sensor open circuit or not connected
◆ HH Alarm
Temperature out of range (-50~110°C)
◆ --- Display
High temperature alarm triggered
◆ Relay Indicator
LED ON = relay closed, OFF = relay open
◆ PCB Dimensions
Approx. 48×40×14mm
◆ Mounting Holes
4x M3 screw holes
◆ Optional Accessory
Acrylic protective case
◆ Operating Environment
-10~60°C / 20%-85% RH
◆ Heating Applications
Aquarium/pet enclosure heating
Incubator temperature control
Fermentation chamber management
Heating pad/blanket control
◆ Cooling Applications
Refrigerator/freezer control
Cooling fan automation
Equipment cabinet cooling
Water cooling system control
◆ DIY Automation
Smart home temperature integration
Arduino/Raspberry Pi expansion
Greenhouse environmental control
3D printer heated bed management
◆ High Precision
0.1°C control accuracy for precision applications
◆ No Programming Required
Standalone operation with button interface
◆ Dual Mode
Heating/Cooling switchable — two devices in one
◆ Rich Parameters
6 adjustable settings for various scenarios
◆ Power-off Memory
Built-in EEPROM saves all settings
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FAQ:
1.What is the XH‑W1209 digital temperature controller and its key specifications?
The XH‑W1209 is a compact programmable thermostat module designed for precise temperature control in heating or cooling applications. It uses a waterproof NTC 10 kΩ thermistor as its temperature sensor, a 10‑A relay as the output switch, and a 3‑digit LED display for status and settings. Key specifications: operating voltage 12 V DC (some variants accept 24 V), measurement range ‑50 °C to +110 °C, control accuracy ±0.1 °C, and a relay rated for 10 A at 250 V AC. The module can be configured for heating mode (relay on when temperature is below set‑point) or cooling mode (relay on when temperature is above set‑point). It also features adjustable hysteresis, temperature calibration, and delayed start protection for compressors.
2.How do I wire the XH‑W1209 to power, a sensor, and a load?
The board has clearly labelled screw terminals. Connect 12 V DC (or 24 V depending on your model) to the +V and GND power terminals — polarity is important; reverse connection may damage the module. The NTC sensor connects to the two‑pin terminal labelled Sensor (non‑polarised). The relay output provides NO (normally open), COM (common), and NC (normally closed) contacts. To control a load (heater, fan, compressor), wire the power source to COM and the load to NO. The relay contacts are isolated and can switch up to 10 A at 250 V AC. After wiring, the display lights up and shows the current temperature.
3.How do I set the target temperature and switch between heating and cooling modes?
Press the SET button once to enter the set‑point mode; the display flashes. Use the UP and DOWN buttons to adjust the desired temperature. Press SET again to confirm. To change the operating mode, long‑press SET for 3 seconds to enter the parameter menu. Scroll to parameter P0 and set it to H for heating mode or C for cooling mode. In heating mode, the relay closes when the temperature falls below the set‑point; in cooling mode, it closes when the temperature rises above the set‑point. The on‑board LED indicates relay status.
4.What is hysteresis (parameter P1) and how do I set it?
Hysteresis (also called differential or dead‑band) prevents the relay from chattering on and off rapidly near the set‑point. For example, in heating mode with a set‑point of 25 °C and hysteresis of 1 °C, the relay turns on at 24 °C and turns off at 25 °C. To adjust, enter the parameter menu (long‑press SET), navigate to P1, and use UP/DOWN to set the desired value (0.1 °C to 30 °C). A smaller hysteresis provides tighter control; a larger hysteresis reduces relay cycling and is better for compressors.
5.Can I calibrate the temperature reading of the XH‑W1209?
Yes, the module includes a temperature calibration function (parameter P2). If the displayed temperature differs from a known reference thermometer, you can apply an offset. Enter the parameter menu, go to P2, and set a positive or negative correction value (range ‑10.0 °C to +10.0 °C). For example, if the sensor reads 24.5 °C but the actual temperature is 25.0 °C, set P2 to +0.5 °C. The module will then display the corrected value. Re‑calibrate after replacing the sensor or if large measurement errors appear.
6.What is the compressor delay protection (parameter P4), and why is it important?
Parameter P4 sets a minimum off‑time for the relay after it has been switched off. This is essential when controlling refrigeration compressors or air conditioners, which should not be restarted immediately after stopping (to avoid damage from high back‑pressure). The delay can be set from 0 to 10 minutes. When the relay turns off, the module counts down the delay and ignores any new cooling demand until the timer expires. If you are controlling a heater or a simple fan, set P4 to 0 to disable the delay.
7.How can I reset the XH‑W1209 to factory default settings?
There is no single‑button factory reset, but you can manually restore the default values by entering the parameter menu and adjusting each parameter to its original setting. The typical factory defaults are: P0 = H (heating), P1 = 0.5 °C (hysteresis), P2 = 0.0 °C (calibration), P3 = 0 (unused), P4 = 0 min (compressor delay), P5 = 0 (unused), P6 = 0 (high‑temperature alarm, off). If the module behaves erratically, power‑cycle it and re‑enter the desired settings.
8.What is the maximum switching capacity of the relay, and can it directly drive a heater?
The on‑board relay is rated for 10 A at 250 V AC (resistive load) and 10 A at 30 V DC. This means it can directly switch most small‑ to medium‑sized resistive heaters, fans, pumps, and solenoid valves. For inductive loads (motors, compressors), the current rating must be derated, and an external snubber circuit or MOV should be used across the relay contacts to suppress voltage spikes. If the load exceeds the relay rating, use an external contactor or solid‑state relay (SSR) driven by the XH‑W1209’s relay. The relay is galvanically isolated from the control circuit.
9.What sensor comes with the XH‑W1209, and can I extend the cable?
The module is supplied with a waterproof NTC thermistor (10 kΩ at 25 °C) with a ~1 m cable. The sensor is sealed in a stainless‑steel or plastic tube, making it suitable for liquid immersion, aquariums, refrigeration ducts, and outdoor use. You can extend the cable up to several metres using a standard two‑core wire (twisted pair recommended for noise immunity). Keep the extension away from high‑current AC cables to avoid interference. If you need a different sensor type (e.g., a bare‑bead NTC for faster response), it must also be a 10 kΩ NTC with the same beta coefficient (typically B = 3950).
10.What are the most common problems, and how can I troubleshoot them?
• Display shows “LLL” or “HHH” — the sensor is open‑circuit (LLL) or short‑circuited (HHH); check the sensor connection and cable.
• Relay does not switch — verify the mode (P0) is correct; check that the temperature has actually crossed the set‑point ± hysteresis; listen for the relay click.
• Inaccurate readings — use the calibration (P2) to correct the offset.
• Display flickers or module resets — the power supply may be unstable; use a regulated 12 V supply with at least 200 mA capability.
• Relay chatters rapidly — increase the hysteresis (P1) to at least 0.5 °C.
11.What are the most typical applications for the XH‑W1209 thermostat?
It is used in incubators, aquarium temperature control, pet terrariums, fermentation chambers, small greenhouses, DIY air conditioners, server cabinet cooling, 3D printer enclosure heaters, and any project that needs automatic heating or cooling within a predefined temperature range. Its low cost, simplicity, and on‑board relay make it a favourite for both hobbyist and light‑industrial automation tasks.