W1209 Programmable Digital Thermostat – Automatic Temperature Control from -50°C to +110°C
Whether you are managing a DIY fridge, an incubator, an aquarium, or a solar heating system, maintaining precise temperatures is essential. Without a dedicated controller, you risk overheating your equipment or wasting energy. The W1209 digital thermostat offers a compact, reliable, and affordable solution for automated temperature management.
Note: For electrical loads exceeding 20A, we recommend using an external contactor controlled via the thermostat’s relay.
Why choose this model? (Key Advantages):
- Wide Measurement Range — Covers -50°C to +110°C, making it equally effective for deep-freeze applications or high-heat resistance setups.
- 20A Dual Relay (NO/NC) — Capable of directly controlling small compressors, heating elements, or solenoid valves without the need for additional circuitry.
- 0.1°C Resolution — Provides precise readings and reacts to minimal temperature fluctuations, which is critical for sensitive processes.
- Fully Programmable Parameters — Features heating/cooling modes, adjustable hysteresis, activation delay, sensor calibration, and high-temperature alarms.
- Low Power Consumption — Operates on just 35–65mA, making it ideal for battery or solar-powered systems.
- NTC Probe Included — Ready to use straight out of the box with no extra accessories required.
Performance and Specifications
The W1209 module updates its readings every 0.5 seconds, ensuring the relay reacts quickly to sudden temperature changes—a vital feature for refrigeration where every degree matters. The NO/NC dual relay provides complete flexibility, allowing you to use direct or inverse logic without modifying your electrical wiring. If the included NTC probe does not meet your specific length or application requirements, the module is also compatible with PTC sensors. Its compact 48.5 x 40 mm footprint makes it easy to integrate into any housing or electrical panel.
| Parameter | Value / Detail |
|---|---|
| Temperature Measurement Range | -50°C to +110°C |
| Sensor Compatibility | NTC (included), PTC |
| Display Resolution | 0.1°C |
| Measurement Accuracy | ±0.1°C |
| Hysteresis Accuracy | 0.1°C |
| Refresh Rate | 0.5 seconds |
| Current Consumption | 35mA – 65mA |
| Display | 0.28-inch 3-digit LED |
| Supply Voltage | 12V DC |
| Maximum Relay Current | 20A |
| Relay Type | Dual: Normally Open (NO) / Normally Closed (NC) |
| Operating Temperature | -10°C to +60°C, 20%–85% humidity |
| Module Dimensions | 48.5 x 40 mm |
Programming and Usage Instructions
- Press and hold the SET button for 5 seconds to enter the parameter menu.
- Navigate through parameters using the + and – buttons, and confirm your selection with SET.
- P0 – Operating Mode: C (Cooling) / H (Heating) — default: C
- P1 – Hysteresis: range 0.1–30°C — default: 2
- P2 – Upper Temperature Limit: max 110°C — default: 110
- P3 – Lower Temperature Limit: min -50°C — default: -50
- P4 – Sensor Calibration: -7°C to +7°C — default: 0
- P5 – Relay Activation Delay: 0–600 seconds — default: 0
- P6 – High-Temperature Alarm: 0–110°C — default: OFF
- To reset to factory settings: press and hold the + and – buttons simultaneously.
- For the most accurate readings, mount the sensor bulb facing upwards, away from direct air currents.
Package Contents
- 1x W1209 Digital Thermostat Module
- 1x NTC Temperature Probe
Frequently Asked Questions
What power supply does the W1209 thermostat require?
It operates exclusively on 12V DC. To use it with a 230V AC mains supply, you will need a suitable power adapter or transformer.
Can it control a refrigeration compressor or a heating element?
Yes. The 20A relay supports direct control of small compressors, electric heaters, solenoid valves, and fans. For loads exceeding 20A, please connect an external electrical contactor controlled via the relay.
Can the included NTC probe be replaced with a longer one or a different type?
Yes, the module supports both NTC and PTC probes. You can use a probe with a longer cable or different specifications without needing any hardware modifications.
How do I switch between cooling and heating modes?
Enter the menu (hold SET for 5 seconds) and adjust parameter P0: select H for heating or C for cooling.
What is the practical difference between NO and NC contacts?
The NO (Normally Open) contact closes when the relay is activated—used when you want the equipment to start once the set temperature is reached. The NC (Normally Closed) contact opens upon activation—useful when you need to switch off equipment once the threshold is reached.
Photo Gallery
B****** D***s –
Amazing little board. I use it to trigger a cooling fan and it hasn’t let me down.