Resideo Q340A1108 Thermocouple

The Resideo Q340A1108 Thermocouple is a heavy-duty, universal pilot safety component designed for standing pilot systems in residential and commercial gas-fired equipment. This 48-inch thermocouple provides a reliable 30mV nominal output, with an open circuit range of 26mV to 32mV, ensuring consistent millivolt signal transmission to the gas valve. Engineered with a low internal resistance of 0.03 Ohms, it minimizes voltage drop to prevent nuisance pilot outages. The lead features an 11/32-32 male connector nut for a secure fit into standard gas control blocks. To simplify field replacement, this unit includes a universal adapter and a push-in clip, making it a versatile replacement thermocouple for furnaces, water heaters, and boilers. Its robust construction is built to withstand high combustion chamber temperatures while maintaining accurate thermoelectric response for critical safety shut-off functions.

• Standard 30mV Output: Ensures compatibility with a wide range of millivolt gas valves and pilot burners.
• Extended 48-Inch Lead: Provides sufficient length for large-scale boiler cabinets and reach-in furnace configurations.
• Low Resistance Core: 0.03 Ohms resistance ensures maximum current flow for reliable electromagnet engagement in the valve.
• Universal Mounting Kit: Includes the necessary push-in clip and adapter to replace most OEM pilot assemblies.

What causes a thermocouple to fail prematurely?
Repeated thermal stress, soot accumulation on the hot junction, or flame impingement cooling can degrade the junction. If the pilot flame is too small or blue-only, it may not generate the necessary 26mV-32mV for the valve to stay open.

Is the Q340A1108 compatible with electronic ignition systems?
No, this is a standing pilot thermocouple designed for millivolt systems. Electronic or intermittent pilot systems typically require a flame sensor or a powerpile/thermopile generator depending on the circuit voltage requirements.

How tight should the 11/32 connector nut be?
Finger-tighten the nut into the gas valve, then turn it an additional 1/4 turn with a wrench. Over-tightening can damage the internal copper lead or the valve's connection point.

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.