What Is Thermocouple In Water Heater?

Understanding what a water heater thermocouple is and how it works is important for homeowners who want to ensure their water heater is always in good working condition. A thermocouple, also referred to as a “temperature sensing device”, is a safety device located on gas-fired water heaters that shuts off the gas if the pilot light goes out.

In this article, we will discuss what a thermocouple is and how it works, potential problems, and basic tips for maintenance. Whether you are a seasoned homeowner or a new homeowner, this article will provide insight into the importance of the thermocouple and its role in keeping your water heater running smoothly and safely.

What is thermocouple in water heater?

A thermocouple in a water heater is an electrical device that is used to measure the temperature of the hot water that is flowing through it. It consists of two wires (usually copper and nickel or iron and nickel) connected to a sensing unit.

When the hot water coming out of the water heater passes through the thermocouple, the electrical current changes in both wires. This is measured by the sensing unit, which then sends a signal to the water heater’s control board signaling to heat up or cool down the water, depending on the detected temperature.

How Does A Thermocouple Work?

A thermocouple works by detecting the temperature of the hot water passing through it. It consists of two wires that are connected to a sensing unit.

When hot water passes through the thermocouple, the current flowing between the two wires changes. This change in current is detected by the sensing unit and is sent to the control board.

The control board then turns on or off the heater to control the water temperature accordingly.

Advantages of Having a Thermocouple in Water Heater

  • Provides Accurate Temperature Measurement: A thermocouple provides an accurate measurement of the water temperature as it has the ability to detect even the slightest of temperature changes.
  • Highly Reliable: A thermocouple is much more reliable than other temperature measuring devices such as thermistors or pressure switches.

  • Easy Maintenance: A thermocouple requires minimal maintenance and is easy to install.
  • Cost Effective: Installing a thermocouple is much more cost-effective than purchasing an additional hot water temperature controller.


A thermocouple in a water heater is an important component for ensuring accurate water temperature control. It is more reliable compared to other temperature measuring devices and requires minimal maintenance. Installing a thermocouple is also cost-effective. Therefore, it is an important component to consider when purchasing a new water heater.

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