Utica-Dunkirk 40154B008 Limit Switch

The Utica-Dunkirk 40154B008 Limit Switch is a critical high-limit safety control designed for specific residential and commercial hydronic heating systems. Rated for an operating range of 170-200F, this automatic reset limit switch monitors heat exchanger temperatures to prevent thermal runaway and equipment damage. As a genuine OEM Utica boiler replacement part, it ensures precise calibration within the aquastat control circuit, maintaining system integrity during the combustion cycle. This L170-20F temperature switch is engineered for high-cycle reliability, providing a normally closed (NC) circuit that opens when the 200°F threshold is breached. For contractors servicing Dunkirk gas boilers or Utica hydronic units, utilizing this exact 40154B008 thermal switch is essential for meeting manufacturer specifications and maintaining the pressure vessel safety rating. Its compact footprint and standard mounting flange allow for streamlined field replacement in tight vestibules.

Key Benefits for Technicians:

• Precision Temperature Cut-out: Calibrated for a 170°F to 200°F range to ensure thermal safety without premature nuisance tripping.
• Automatic Reset Functionality: Restores circuit continuity once temperatures drop below the 170°F differential, reducing unnecessary service calls.
• Broad Compatibility: Engineered specifically for Utica and Dunkirk hydronic systems, ensuring a perfect fit and electrical match.
• Industrial-Grade Construction: Built to withstand the high-ambient heat environments found in modern gas-fired boiler cabinets.

Common Technical Questions:

When should the 40154B008 limit switch be replaced?
If the boiler fails to fire despite a call for heat, or if the unit is cycling on the limit switch below the 200°F threshold, the internal bimetal disc may have fatigued, requiring a new Utica 40154B008.

Is this switch compatible with electric boilers?
This specific limit is designed primarily for gas-fired hydronic systems. Consult your wiring diagram to ensure the voltage and amperage ratings align with your specific control board requirements.

Can I bypass this limit for testing purposes?
Temporary bypassing is only for immediate diagnostic continuity testing by a licensed professional. Running a system without a functional 200F auto limit switch creates a significant safety hazard.

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.