Hydrolevel 48-3250-59 Replacement Sensor

For technicians servicing hydronic systems, the Hydrolevel 48-3250-59 Replacement Sensor is the direct OEM solution for maintaining signal integrity in HydroStat 3000 and 4000 series controllers. This 24-inch thermistor sensor assembly provides the precise thermal feedback necessary for the controller?s low water cut-off (LWCO) and temperature limit functions. When a hydronic boiler temperature sensor fails, it often triggers nuisance lockouts or inaccurate firing cycles; this Hydrolevel replacement part restores factory-spec resistance-to-temperature curves. The 24" lead length allows for flexible routing through the jacket to the immersion well, ensuring the thermistor bulb sits deep enough to avoid ambient air interference. Engineered as a high-reliability HVAC temperature probe, it integrates seamlessly with existing HydroStat 3250-Plus and similar 3000/4000 series logic boards without requiring field calibration. Professional-grade construction prevents moisture ingress at the sensing tip, a common cause of drift in aging hydronic sensors.

Technical Specifications and Benefits

• Direct Compatibility: Engineered specifically for Hydrolevel HydroStat 3000 and 4000 series digital limit controllers.
• Precise Thermal Feedback: High-accuracy thermistor sensor ensures the controller maintains tight differential control for fuel economy.
• Optimal Lead Length: The 24-inch sensor lead provides ample slack for proper cable management within the boiler cabinet.
• Critical Safety Integration: Restores dependable low water cut-off sensing when paired with the appropriate Electro-Well.
• Rugged Build: Designed to withstand the high-temperature environment of residential and commercial hydronic heating applications.

Common Questions

Will this sensor work with all HydroStat models?
The Hydrolevel 48-3250-59 is compatible with most 3000 and 4000 series controllers, including the 3250-Plus. Always verify the lead length and plug configuration against the existing harness before installation.

What are the symptoms of a failing Hydrostat sensor?
Common indicators include erratic temperature displays, "Sensor Shorted" or "Sensor Open" error codes on the LED interface, and the boiler failing to fire despite a call for heat.

Does this include the immersion well?
This is the replacement thermistor sensor and lead only. If the internal well is corroded or leaking, a separate Hydrolevel Electro-Well must be sourced to ensure the probe remains dry and responsive.

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.