Resideo Q390A1053/U 30 mV Thermocouple Includes a 30 in Leads, 11/32-32 Male Connector Nut Connection, Push-In Clip, and Adapter Assembly

The Q390A1053 is a thermocouple from Resideo (Honeywell Home), 30 inches long, 30 mV output.

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.

The 11/32-32 male connection is the standard gas valve thread for this class of thermocouple.

• Brand: Resideo (Honeywell Home)
• Manufacturer Part #: Q390A1053/U
• Type: Thermocouple
• Output: 30 mV
• Length: 30 in
• UPC: 085267069274
• Category: Thermocouples & Thermopiles

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