Honeywell Q390A1046 Thermocouple

The Honeywell Q390A1046 Thermocouple is a high-performance pilot safety component engineered for gas-fired heating systems requiring a reliable 30mV thermocouple signal. This 24-inch lead assembly delivers a consistent open circuit output between 26mV and 32mV, ensuring the electromagnetic coil in the gas valve remains energized during steady-state operation. With a low internal resistance of 0.02 Ohms, it minimizes voltage drop to prevent nuisance furnace pilot outages. The 11/32-32 male connector nut provides a secure mechanical interface with the pilot burner, while the included push-in clip and adapter simplify retrofitting. As the direct replacement for the 21724B thermocouple, this unit is essential for HVAC troubleshooting on standing pilot systems. Whether you are performing a water heater thermocouple replacement or servicing a commercial boiler, the Q390A1046 provides the thermal response and millivolt stability required for peak safety performance.

• Precise Millivolt Output: Maintains an optimal 26mV-32mV range to ensure reliable gas valve hold-in.
• Universal Compatibility: Includes specialized mounting hardware and adapters for versatile field installation.
• Direct OEM Replacement: Engineering match for the 21724B, eliminating guesswork during pilot burner repair.
• Durable Construction: Designed to withstand high-temperature combustion environments without signal degradation.

Is the Q390A1046 compatible with electronic ignition systems?
No, this is a millivolt-style thermocouple designed specifically for standing pilot applications. It is not a flame sensor for intermittent pilot or direct spark ignition systems.

What is the cause if my thermocouple voltage is dropping below 20mV?
Low output typically indicates soot buildup on the tip, improper flame impingement, or high internal resistance due to age, necessitating a replacement.

How do I install the honeywell q390a thermocouple?
Ensure the tip is submerged 3/8" to 1/2" in the pilot flame, tighten the 11/32" nut 1/4 turn past finger tight, and use the provided clip for proper alignment.

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.