Resideo Q340A1090/U 36" Thermocouple

Item #: HONE-Q340A1090/U
Mfr. part #: Q340A1090/U
UPC: 085267067430

Key specifications

Connection11/32 32 Male Connector Nut
Resistance0.02 ohms
Length36 in.

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$14.53

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Shipping weight: 0.12 lb
Box size: 4.6 × 4.55 × 0.65 in

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Brand	Resideo
Manufacturer part #	Q340A1090/U
Connection Type	11/32 32 Male Connector Nut
Voltage	30 mV; Open circuit output--26 mV to 32 mV
Application	Thermocouple for Standing Pilot Applications
Includes	Adapter and Push In Clip
Temperature Ratings (F)	Hot Junction--1400 F; Cold Junction--780 F
Resistance	0.02 ohms
Length (in.)	36 in.
Prop 65 Warning	WARNING/CA WARNING/CALIFORNIA WARNING: “Risk of cancer and reproductive harm from exposure to [Lead]. See www.P65Warnings.ca.gov.”
UPC	085267067430

The Q340A1090 is a thermocouple from Resideo (Honeywell Home), 36 inches long.

The thermocouple is the safety device on a standing pilot appliance. Its tip sits in the pilot flame and generates a small DC voltage, and that voltage is what holds the pilot safety valve open. Lose the flame, lose the voltage, and the valve closes within seconds — no electronics, no power supply, nothing to fail closed.

Output is measured in millivolts, and it falls as the tip oxidizes. A pilot that lights, holds while the button is pressed, and drops the moment the button is released is the classic sign: the thermocouple is still making some voltage but no longer enough to hold the valve in.

Length is what makes one thermocouple different from another in this family. Buy the length that reaches, and route the lead away from the flame path — a thermocouple lead cooked against the burner fails early and looks fine doing it.