Weil McLain 389-900-229 Sensor

The Weil McLain 389-900-229 Sensor is a critical 10k ohm NTC component designed for multi-functional integration within hydronic heating systems. Engineered for high-accuracy thermal feedback, this Universal 3-In-1 Sensor serves as an outdoor reset sensor, an indoor strap-on supply sensor, or a specialized well sensor depending on your installation requirements. When utilized as an outdoor sensor, it allows the boiler control to modulate water temperatures based on ambient conditions, significantly improving boiler heating efficiency and reducing short-cycling. The kit typically includes the sensor head and a weatherproof enclosure to ensure long-term durability against environmental exposure. For contractors performing maintenance on BMC or BMC-6X series controllers, this sensor is the direct replacement part for maintaining precise outdoor reset control logic. Its versatility as a strap-on sensor makes it ideal for monitoring secondary loop temperatures or system headers without tapping into the piping, ensuring a non-invasive yet accurate HVAC temperature monitoring solution for any commercial or residential Weil McLain application.

• Multi-Application Versatility: Can be configured as an outdoor ambient sensor, a pipe-mounted strap-on sensor, or a thermal well immersion sensor.
• System Efficiency: Enables outdoor reset functionality to optimize fuel consumption and maintain consistent indoor comfort.
• Rugged Construction: Features a weatherproof temperature sensor housing that protects internal thermistor logic from moisture and debris.
• Simplified Integration: Direct compatibility with Weil McLain control boards, requiring no external conversion modules for 10k ohm resistance signaling.

What is the resistance value of the 389-900-229 sensor?
This is a standard 10k ohm NTC (Negative Temperature Coefficient) sensor. Resistance decreases as the temperature rises, allowing the controller to calculate precise thermal data.

Can I extend the wiring for this sensor?
Yes, you can typically extend the sensor leads up to 500 feet using 18 AWG shielded twisted-pair wire to prevent electromagnetic interference from affecting the readings.

Where should the sensor be mounted for outdoor reset?
For the most accurate outdoor temperature readings, mount the sensor on the North side of the structure, at least 10 feet above grade, away from exhaust vents, windows, or direct sunlight.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.