What is a Thermocouple and How Does it Work?

Dec 18, 2017 | Heating

Thermocouples are sensors used to measure temperature. It is a device used inside a gas furnace in Kansas, to assist the pilot light in keeping your furnace running and safe. It works rather like a fail-safe to keep unburned gas from accumulating and burning, exploding or causing another type of health risk.

A thermocouple consists of two wires, or wire legs, made from different metals. The legs are welded together at one end, into a junction, where the temperature is measured. A voltage is created when the junction senses a change in temperature. The voltage can then be interpreted using thermocouple reference tables to calculate the temperature.

There are many types of thermocouples. Different types are best suited for different applications. Usually they’re selected on a temperature-range and sensitivity-needed basis. Thermocouples are available in different combinations of metals or calibrations: base metal thermocouples, Types J, K, T, E, and N, are the most common; nobel metal thermocouples, Types R, S, C, and GB, are high-temperature calibrations. Call B&C Mechanical with any questions you may have about thermocouples. Our experienced technicians have the necessary knowledge and training to answer your questions.

Every calibration has a different environment and temperature range, though the maximum temperature is contingent upon the diameter of the thermocouple wire used. Therefore, a very thin thermocouple may not reach the full-temperature range. Because of its low cost and temperature range, the K type thermocouple is known as a general-purpose thermocouple.

Due to thermocouples measuring in wide temperature ranges and being comparatively rugged, they are often used in industry. When choosing a thermocouple, the following factors must be considered for the best result:

  • Determine the application where the thermocouple will be used.
  • Analyze the temperature ranges for the thermocouple exposure.
  • Assess any chemical resistance needed for the thermocouple or sheath material.
  • Evaluate the need to abrasion and vibration resistance.
  • List all, if any, installation requirements.

Thermocouples are usually selected based on their high-temperature limits, wide temperature ranges, low cost, and durable nature. They’re used in a wide range of temperature-measurement processes, typically science, industry, and OEM applications. Thermocouples are used in nearly all industrial markets, such as cement, oil/gas, power generation, biotech, and paper and pulp. They are also used in everyday Kansas appliances like furnaces, toasters, and stoves.

Request service online today. B & C Mechanical provides commercial repair, replacement, installation, and maintenance services to residents in Kansas and Missouri. From Olathe to Kansas City, Blue Springs to Raytown, we are the #1 HVAC company in the area. Visit our service area page for the list of communities we serve. We service residents in areas surrounding these towns as well. If you don’t see your town listed, call us at 913-681-0088 and find out what we can do for you.


B & C Mechanical is proud to offer commercial heating and cooling services to residents in Kansas and Missouri. In Kansas, our service ares include Olathe, Overland Park, Leawood, Lenexa, Prairie Village, Shawnee, Merriam, Mission, Kansas City, Roeland Park, and surrounding communities. In Missouri, our service areas include Blue Springs, Gladstone, Grandview, Independence, Lees Summit, Liberty, North Kansas City, Raytown, South Kansas City, and surrounding communities. Call us now at 913-681-0088 or request service online.