W1209 12V Digital Thermostat Temperature Controller Module with NTC Sensor – Heating & Cooling Automation

Automate Temperature Control for Any DIY Project The W1209 Digital Thermostat Temperature Controller Module is a compact, self-contained solution for automating heating and cooling devices based on real-time temperature readings. Whether you're building a homebrew fermentation chamber, a reptile habitat controller, a greenhouse ventilation system, or a 3D printer enclosure heater, the W1209 gives you precise, programmable temperature control at a fraction of the cost of commercial thermostats. Simply connect 12V DC power, wire your heating or cooling device to the onboard relay, plug in the included NTC temperature sensor, and set your target temperature. The module does the rest — continuously monitoring the ambient temperature and switching your device on or off to maintain your desired setpoint. ⚠️ NOTE: This is the standard 12V Version of the W1209 Temperature Controller We also offer a 24V version, which requires 24V support power:   24V W1209 Temperature Controller Why Choose This Module? Ready to use out of the box — Includes the controller board and a waterproof NTC temperature sensor probe with cable. No soldering, no additional components needed. Wide temperature range — Measures from -50°C to 110°C (-58°F to 230°F) with ±0.1°C resolution, suitable for freezer monitoring, incubation, fermentation, and high-heat applications. Powerful onboard relay — Switches loads up to 10A at 120VAC or 10A at 14VDC, enough to directly control fans, small heaters, solenoid valves, Peltier coolers, and more. Heating AND cooling modes — Configurable for either heating (relay ON when temp drops below setpoint) or cooling (relay ON when temp rises above setpoint) via a simple menu setting. Adjustable hysteresis — Set a temperature differential (1°C–15°C) to prevent rapid relay cycling, extending the life of your connected equipment. Bright LED display — Easy-to-read 3-digit display shows the current temperature at a glance, even in dim environments. Simple 3-button interface — Set/Menu, Increment (+), and Decrement (–) buttons make programming fast and intuitive. No complicated menus or manuals required. Compact footprint — Board measures just 48mm × 40mm — small enough to embed into enclosures, control panels, or project boxes. Temperature alarm — Configurable high and low temperature alarm thresholds alert you when conditions move outside your desired range. Sensor delay protection — Built-in delay setting prevents false triggering from momentary temperature fluctuations. Popular Applications Application Mode How It Works 🍺 Homebrew / Fermentation Cooling Activates a fan or cooler when wort temperature rises above target 🐍 Reptile / Terrarium Heating Heating Turns on a heat lamp or heat mat when enclosure cools below setpoint 🌱 Greenhouse / Grow Room Cooling Triggers exhaust fans when temperature exceeds threshold 🖨️ 3D Printer Enclosure Heating Maintains stable chamber temperature for ABS/ASA printing 🧊 Mini Fridge / Kegerator Cooling Controls compressor or Peltier module to maintain cold storage temp 🐔 Egg Incubator Heating Keeps incubation temperature steady for optimal hatch rates 🏠 Pipe Freeze Protection Heating Activates heat tape when ambient temp drops near freezing 🔧 Equipment Cooling Cooling Turns on cooling fans when electronics or machinery overheat Technical Specifications Parameter Value Supply Voltage DC 12V (9V–12V operating range) NOTE: The maximum input support voltage should not exceed 12V. In applications such as an automobile or RV where the battery voltage can exceed 12V, a regulator circuit or a 12V to 9V buck voltage converter with the input to the converter connected to the battery and the output to the W1209 will provide a stable 9V DC supply for the W1209 Temperature Range -50°C to 110°C (-58°F to 230°F) Measurement Accuracy ±0.1°C resolution Temperature Sensor NTC 10K thermistor (0.5% tolerance), waterproof probe Relay Output 1 channel, 10A @ 120VAC / 10A @ 14VDC Control Modes Heating (H) or Cooling (C), user-selectable Hysteresis Range 1°C to 15°C, adjustable Display 3-digit red LED, 0.36" Refresh Rate 0.5 seconds Static Current ≤35mA Operating Current ≤65mA Board Dimensions 48mm × 40mm (1.9" × 1.6") Operating Humidity 20%–85% RH (non-condensing) Programmable Settings at a Glance The W1209 features seven user-configurable parameters accessible through a simple long-press menu: Code Setting Range Default P0 Heat / Cool Mode H (Heat) / C (Cool) H P1 Hysteresis 1°C – 15°C 2°C P2 Upper Temp Limit — 110°C P3 Lower Temp Limit — -50°C P4 Temperature Correction Offset -7°C to +7°C 0°C P5 Relay Activation Delay 0 – 10 minutes 0 min P6 High Temperature Alarm — OFF Quick Start Guide Connect power: Wire 12V DC to the power input terminals (+ and –). Attach the sensor: Plug the NTC sensor probe into the 3-pin header on the board. Wire your load: Connect your heating or cooling device to the relay output terminals (K0 and K1). The relay acts as a simple on/off switch. Set your target temperature: Use the + and – buttons to set your desired temperature on the display. Configure mode: Long-press the SET button to enter the settings menu. Set P0 to H for heating or C for cooling. Done! The module will now automatically control your device to maintain the target temperature. ⚠️ Important: This is the 12V version. We also offer a 24V version that requires 24V DC input for proper operation. If you need a 24V version, please see our W1209 24V Digital Thermostat Controller. 📘 Full installation and programming instructions are available on our support page: W1209 Installation & Operating Instructions Display Error Codes Code Meaning LLL Sensor disconnected or temperature below range HHH Temperature above measurable range 888 Sensor is disconnected. Plug a 10K NTC thermistor into the module --- Sensor short circuit Pro Tips Extend sensor cable carefully: The NTC sensor cable can be extended up to ~5 meters using shielded wire without significant accuracy loss. Beyond that, consider using a shorter run or adding a pull-up resistor for signal integrity. Use with a relay module for higher loads: While the onboard relay handles up to 10A, for high-power devices (space heaters, large compressors), use the W1209 relay output to trigger a higher-rated external relay or contactor. Calibrate with P4: If your sensor reads slightly high or low compared to a reference thermometer, use the P4 temperature correction offset (±7°C) to fine-tune accuracy. Mount in a ventilated enclosure: For long-term installations, house the board in a project box with ventilation holes to protect it from dust and moisture while allowing airflow to the board. What's in the Box ✅ 1× W1209 Digital Thermostat Controller Board ✅ 1× Waterproof NTC Temperature Sensor Probe with 0.5M (~18 inch) cable Note: 12V DC power supply and load wiring are not included. A 12V battery or standard 12V DC adapter (minimum 1A recommended) is required for operation. 📄 Documentation & Resources User Manual & Hookup Guide (English)  User Manual & Hookup Guide (Español/Spanish)  All Temperature Measurement & Control Guides Need a longer probe? See our 1 Meter long NTC Thermistor Probe that can be used with the W1209. Want a W1209 with an acrylic plastic case: Click on this link to our W1209 with a case.