null

Thermocouples

Thermocouples

Shop furnace and water heater thermocouples for pilot ignition systems. Furnace Part Source carries snap-fit, universal, and OEM thermocouples from Robertshaw, Honeywell, Rheem-Ruud, Lochinvar & A.O. Smith, Utica-Dunkirk, and other leading brands by length and millivolt output.

Use the product list below to find the correct thermocouple by part number, length, or equipment model. Always confirm the length, millivolt output, and connection type before ordering to help avoid fitment issues.

  • Product
  • Qty in Cart
  • Quantity
  • Price
  • Subtotal
  • Total: items /

Adding your products to cart

View Cart Continue Shopping

Furnace Thermocouples

A thermocouple is a safety device that detects whether the pilot flame is lit and signals the gas valve to remain open. If the pilot flame goes out, the thermocouple cools and shuts off gas flow, which helps prevent unburned gas from accumulating.

Furnace Part Source carries a range of thermocouples for residential and light-commercial furnaces, boilers, and water heaters, including snap-fit designs, universal replacement thermocouples, and OEM-specific parts.

Common Thermocouple Parts We Carry

Common replacement thermocouples include:

  • Snap-fit thermocouples that connect without threading into the pilot burner.
  • Threaded thermocouples for OEM and standard pilot burner connections.
  • Universal replacement thermocouples designed to cross-reference several OEM part numbers.
  • High-temperature thermocouple kits for water heater and specialty applications.

How to Find the Right Thermocouple

Before ordering, check the existing thermocouple for the part number and length, which is typically measured from the tip to the connection nut. Confirm the connection style, since snap-fit and threaded thermocouples are not interchangeable without an adapter.

For best fit, compare:

  • Original thermocouple part number
  • Length, typically measured in inches
  • Connection style, such as snap-fit or threaded
  • Millivolt output, if specified by the equipment manufacturer

Thermocouples From Leading HVAC Brands

Our catalog includes thermocouples from Robertshaw, Honeywell, Rheem-Ruud, Lochinvar & A.O. Smith, Utica-Dunkirk, Williams Comfort Products, Nordyne, Reznor, BASO, and other major manufacturers, covering a range of lengths and connection styles.

Need Help Matching a Thermocouple?

Not sure which thermocouple you need? Use the length and part number from your existing thermocouple to narrow the search, or contact Furnace Part Source for help identifying the correct replacement.

Thermocouple FAQs

What does a thermocouple do?

A thermocouple senses heat from the pilot flame and generates a small voltage that holds the gas valve open. If the pilot goes out, the thermocouple cools and the valve closes to stop gas flow.

What are signs of a failing thermocouple?

Common signs include the pilot light going out repeatedly, the pilot lighting but not staying lit, or the main burner failing to ignite even with a lit pilot.

Are all thermocouples the same length?

No. Thermocouples come in various lengths, typically ranging from about 18 to 72 inches. Measuring the original thermocouple is the most reliable way to confirm the correct replacement length.

Can I use a universal thermocouple on any furnace?

Universal thermocouples are designed to fit a range of equipment, but you should still confirm the length, connection style, and millivolt output match your original part before ordering.