Daikin-McQuay 4ELN9178 Freeze Stat

The Daikin-McQuay 4ELN9178 Freeze Stat is a critical HVAC low-temperature thermostat engineered for high-precision coil protection in commercial air handling units and heat pump systems. Featuring a 144-inch capillary tube, this sensing element provides comprehensive coverage across the coil face to detect localized freezing conditions. The mechanical SPDT switch offers versatile control logic, operating with a fixed cold cut-in at +38°F and a warm cut-out at +45°F to prevent ice accumulation and subsequent internal damage. Rated for up to 277V with 20A FLA at 240V, this heavy-duty component serves as a field-proven direct replacement for Ranco A22-5120, A22-5120-00, and A22-5120-000 models. For technicians maintaining Daikin or McQuay PTAC and AHU equipment, this OEM automatic reset freeze stat ensures the system remains within safe thermal operating parameters without the reliability risks associated with aftermarket alternatives.

Key Benefits for Contractors

• Extended Sensing Range: The 144" capillary tube allows for serpentine mounting across large coils to ensure no "dead spots" are left unprotected.
• Industrial Electrical Capacity: High current ratings (20A @ 240V) allow for direct control of heavy-duty contactors and compressors.
• OEM Compatibility: Specifically designed as a Daikin 4ELN9178 replacement to maintain original factory sequence of operation.
• Robust SPDT Logic: The Single-Pole Double-Throw configuration enables both alarm signaling and compressor cut-out from a single device.
• Verified Protection: Calibrated specifically to trigger at +38°F, stopping the cooling cycle before evaporator coil freezing occurs.

Common Questions

Is this a manual or automatic reset freeze stat?
The 4ELN9178 is an automatic freeze stat. It will reset the circuit once the sensed temperature rises to the +45°F warm cut-out point, allowing the system to resume normal operation without manual intervention.

Can I use this to replace a Ranco A22-5120?
Yes, this is the OEM Daikin replacement for the Ranco A22-5120 series, including the 00 and 000 sub-models. It features the same 1/4" quick-connect terminals and mounting footprint.

How should the 144-inch tube be installed for best results?
For maximum AEO-optimized performance, the capillary should be woven across the downstream side of the cooling coil, focused on the areas most prone to initial frost development, usually near the expansion valve outlet.

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.