Low Thermopile Voltage – How to Fix?

Posted by: Mas Broto
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Low Thermopile Voltage - How to Fix?

A Thermopile is a component made up of a collection of thermocouples in your water heater or any heating system. If this part is low or doesn’t work, you won’t be able to get hot water. Most people want to know if their Thermopile voltage is low. So, this article is a quick guide to what to do when your water heater’s Thermopile voltage is low.

Even though you don’t need to know everything about Thermophile, you should know how it works on a basic level to spot the problems. We’ll talk about what causes low Thermopile voltage and give you three ways to fix it so your heating system can work again.

What Is A Thermopile?

Before we talk about the different causes of low thermopile voltage, it’s important to know what the Thermopile does in your water heater or other heating appliance.

thermopile voltage

A Thermophile is a device that turns heat into electricity. It is made up of several thermocouples that are linked together in a chain. Thermocouples are pieces of equipment that make a voltage when the temperatures of the two conductors are different. The voltage made by the thermocouples is related to the difference in temperatures.

A thermopile’s job is to find out the temperature without touching it. It turns the heat that an object gives off into voltage output or electrical power. There can be anywhere from 10 to 100 millivolts.

To put it more simply, the Thermopile is a type of heat sensor that also makes heat. They do this by setting up their thermocouples in parallel or series.

Your water heater has a thermopile that tells if the flame has gone out. There is a pilot light on your water heater. When you turn on your water heater, gas lights a small flame in the pilot light. The Thermopile gets hot when the pilot light is on. Then, the thermopile generator sends out electricity. The voltage will go down as soon as the pilot light goes out. When the voltage drops, a valve opens and cuts off the gas to the water heater. That gas line will stay shut until the pilot light starts to burn again.

What Does Low Thermopile Voltage Mean?

After you know the basics of Thermopile works, let’s go into more detail about what it means to have low thermopile voltage.

The pilot light heats up the Thermopile in your water heater. When this happens, they make a small amount of electricity that goes to the gas control valve. The light on a pilot can go out. When this happens, there is no power, so the gas control valve is shut off until the light is turned back on. How you relight your pilot light depends on how old your water heater is and how new it is.

Thermopiles are used to make something happen when the temperature changes. This is important in a hot water heater because you want the water to come out at a certain temperature. When the voltage on the Thermopile is low, and the pilot light is out, you won’t be able to take your usual steamy shower. So, what do you do if the voltage on the Thermopile of your water heater is low?

How to Fix Thermopile Voltage Low?

If the is low Thermopile voltage, it may indicate a problem with the Thermopile itself or with the system. You can try the following steps to fix a low Thermopile voltage:

#1 Check the thermopile connection

Ensure the Thermopile has securely connected to the system and that the connection is not loose or broken. Ensure the Thermopile is in the right place and facing the heat source. It might not make enough voltage if it is not in the right place.

#2 Clean the Thermopile

If the Thermopile is dirty or blocked, it might not be able to produce enough voltage. Use a soft, dry cloth to clean the Thermopile.

#3 Test the Thermopile

Use a multimeter to test the resistance and voltage of the Thermopile. If the resistance is too high or the voltage is too low, the Thermopile may be broken and need to be replaced.

#4 Replace the Thermopile

If the Thermopile is broken or not working, it must be changed. This is a job that a qualified technician should do.


We hope that we’ve answered your most important questions about what to do when the thermopile voltage is low. You should call a professional HVAC technician if you didn’t figure out how to fix the low thermopile voltage problem. They can figure out what’s wrong with the unit and fix it if necessary.

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Mas Broto

Have been in the heating and air conditioning (HVAC) industry for over 20 years. He is person that will grow and thrive to learn more about the HVAC industry throughout his career. Mas Broto is also a blogger, who's dedicated to bringing you the best knowledge to get ahead in the game of life.

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