Thermopile Voltage Low

Thermopile Voltage Low

A thermopile is actually a collection that may introduce together many thermocouples in the context of water heaters and many other heating appliances. 

Thermopiles are used to cause something to happen when the temperature changes. This is important in hot water heaters because you want the water to come out at a certain temperature. 

Thermopiles are interesting devices used to measure temperature variations. In various applications, maintaining the optimal thermopile voltage is critical to ensure accurate readings. 

However, encountering low thermopile voltages can raise questions and concerns. 

As mentioned earlier, this device will convert thermal energy into electrical energy. No wonder it is also used in water heaters. 

It would be hard to get desired normal stream shower, if the voltage of the thermopile will low, and the pilot light goes out.

Thermopile devices are commonly used in heating devices such as gas furnaces, water heaters and other heating devices. 


How Does Thermopile Work Can Guide Us To Know Thermopile Voltage Low 

Before knowing the reason for the thermopile’s low voltage you should understand the role of thermopile in your gas fireplace or other heating appliances. 

These thermocouples are connected in the form of a series. When there is a difference in temperature between the two conductors, the thermocouples produce the voltage. 

Thermocouples will work by measuring the temperature difference from the junction area where the output voltage of the thermocouple was measured. 

Suppose the thermopile could not produce the voltage within a certain threshold. It will not let the valves be opened and gas will not flow to the burners.

The thermopile also produces a voltage used to run the gas valve. That is used to control the flow of gas to the burner. 

Between the two conductors, the temperature differential produces the voltage in a thermopile. 

If the temperature is too low, the voltage will be too low. The thermopile must be at the correct temperature to operate the appliances correctly. 

What Does Thermopile Voltage Low Mean? 

A situation where the output voltage generated by a thermopile becomes below the expected or optimal range. 

When the thermopile drops its voltage below the threshold, it indicates potential issues. Having temperature sensing or the function of the thermopile itself. 

When the unit is unable to convert thermal energy into electric energy, the thermopile has a low voltage. Indeed thermopile needs heat to generate voltage and deliver it to the heating appliances.

A pilot light heats a thermopile in a water heater to generate electricity. This unit connects multiple thermocouples in series or parallel configurations. Electricity is created by the temperature difference between two conductors. 

The thermocouple generates voltage and supplies it through the gas control valve when the burner is turned on. If the current is below a certain level, the devices will not heat up or initiate ignition. 

Additionally, if the pilot light is off, the thermopile does not generate electricity and closes the gas control valve. 

So the mechanism relies on the pilot light and temperature differences to generate enough current for the heating devices. 

In short, a thermopile provides an output in terms of temperature, which is required for water heaters and other heating devices. For the work of these devices, you should be aware of when thermopile voltage low. 

The temperature difference between two conductors is crucial in thermopile voltage. So check out the reasons why your thermopile is running at low voltage.

Thermopiles are used to cause something to happen when the temperature changes. This is important in hot water heaters because you want the water to come out at a specific temperature. 

Generally, this number falls in the range of 650 to 850. A thermopile voltage low means the thermopile voltage has dropped far below this number. This means the voltage has dropped too low. When you want to use your water heater, the gas line is shut off. 

What Are Thermocouples: 

Thermocouples are temperature sensors that use the Seatback effect as their basis for temperature measurement. They are made up of two distinct kinds of metal wires that have been linked at one end to create a junction. 

What Are Thermocouples

This junction produces a modest voltage when subjected to a temperature gradient (a difference in temperature between the two ends). The temperature at the sensing end of the thermocouple can be measured using this voltage, which is proportional to the temperature differential.

The two metal wires that make up a thermocouple are often composed of dissimilar alloys or metal combinations.

Thermocouple types that are most frequently used include: 

Type K: Constructed of Alumel (Nickel-Aluminum) and Chromel (Nickel-Chromium). Due to their wide temperature range and good precision, they are widely used. 

Type J: Constructed of iron and copper-nickel Constantan. They are frequently employed in the food business and are appropriate for lower temperature monitoring. 

Type T: Constructed from copper and constant. They offer high-accuracy measurements for low-temperature applications. 

Type E type T Type J Type N thermocouple

Type E: Constructed of Constantan and Chromel. They are frequently employed in the petrochemical sector and have good precision. 

Type N: Constructed of Nisil (Nickel-Silicon) and Nicrosil (Nickel-Chromium-Silicon). They provide good stability and high-temperature resistance. 

Thermocouples Wires:

A thermocouple consists of a number of wires connected to it. Loose or damaged wires in these wires can cause thermopile voltage low. Thermocouples are usually connected at one end by two metal wires. 

A number of thermocouples are now available in thermopile. Their separate metal junctions use the temperature difference between the two junctions to produce a more accurate voltage. 

Technical Error: 

A final cause of thermopile voltage low is a technical error. This is common with old or damaged thermopile units where the thermocouple wires or metal terminals are damaged. As a result, the unit does not operate on regular days. 

Whenever thermocouples are heated by the pilot light, the metal wires generate a thermoelectric current to pass through the gas control valve. Thermopile voltage low problems will occur if the wiring is damaged or loosely connected. 

There Are Various Common Factors Behind Thermopile Voltage Low

  • Sometimes, you may find that the connected appliances are not working properly and have trouble heating or burning the water. 
  • These symptoms indicate a malfunction due to thermopile low voltage. 
  • Modern heating devices include indicators to ensure continuous internal operation. LEDs will pop up if your water heater or fireplace thermopile runs low voltage. 
  • Old or poor quality thermopiles mainly cause problems during working days. Additionally, some ordinary occasions can also trigger low voltages in these units. 
  • For example, strong winds can blow out the pilot system and affect the voltage output across the thermocouples. 
  • Other problems can arise from falling chimney caps and water heater bottom drafts. 
  • Sometimes thermopile low voltage problems are caused by cold junction faults, loose wires, and faulty internal units.
  • Additionally, the location of your device, such as a windy area, can cause thermopile voltage low issues. 
  • Disrupting the flow of electrical current or a faulty connection may cause the thermopile voltage low. 

A cold junction thermocouple is a process located below the thermopile unit. This electrical device has two junctions, hot and cold. Hot junction contacts the device you want to measure the temperature (water heater, fireplace, etc.). 

The other part is a cold junction which is not in contact with any device but helps keep the temperature constant (like room temperature). Now the voltage output or power of the thermopile depends on the temperature difference between the cold and hot junctions. 

Checking Measures You Should Take To Know About Thermopile Voltage Low 

First, you should ensure the unit is free from these uncertain effects. 

The next step is to check the thermopile to see if there is any technical fault.

Ensure that all connections are fastened and free of damage or corrosion. 

Make sure the requirements of the temperature gradient meets your thermopile because the thermopile depends on the temperature to generate voltage. 

Keep an eye on the thermal insulation around the thermopile which can impact its performance because improper insulation can cause its malfunction. 

And verify that the thermopile is accurately insulated to maintain accurate readings 

Shield your thermopile from adverse environmental factors, like humidity, extreme temperature or exposure to electromagnetic fields. That can disrupt the work of thermopiles. 

Check the age of your thermopiles because tear and wear can degrade the materials’ vulnerability over time, leading to a decrease in voltage issues.

Pay attention to the configuration of your circuit because it can hinder the flow of current through the thermopile. 

Ensure that it is manufactured properly following the manufacturer’s guidelines or schematic diagrams. 

To make sure temperature gradient adequacy according to the desired application. 

To ensure a sufficient temperature between the cold and hot junctions of the thermopile

How You Can Fix Your Thermopile Voltage Low? 

A thermopile voltage low may indicate a problem with the thermopile itself. You can try the following steps to fix this problem. 

Fix The Connection: 

The first thing which can make your thermopile voltage low better is its secure connection to the system. 

Ensure the thermopile is at the right place facing the heat source. So it could produce. 

Clean The Thermopile:

Clean the thermopile if it is dirty or blocked, otherwise, it will not produce enough voltage, always use a soft, dry and clean cloth. 

Two Tests For Thermopile Voltage Low Checking 

There are two ways to test a thermopile, and you can do both of them yourself. Don’t panic. The process is fairly straightforward. Once you have the right tools, you can run this test in no time. You don’t need any experience to work with a water heater other than turning it on. The only thing you need to get started is a multimeter capable of reading millivolts. 

Open Circuit Thermopile Testing 

You need to follow the lighting label on your water heater. Then you can continue to turn on the pilot and let it run for about three minutes. 

If your pilot still doesn’t light, you need to hold the pilot button – turn the gas control knob to the pilot position, and you need to push and keep it – you need to perform this step during the test.

You can use a multimeter, which can measure millivolts, and connect one lead to the left side of the wire harness, and the other lead to the right side of the wire harness. If your meter reads 300 millivolts or more, 

your thermocouple is fine. But if it reads less than 300 millivolts, you need to replace the cushion that is just assembled. 

Closed Circuit: 

You must disconnect the red and white pilot cables from the throttle control. You can use a multimeter, which can measure millivolts, and connect one lead to the red wire and the other lead to the white wire. 

Always follow the lighting instructions on your heater, then turn on the pilot and let the heater run for about three minutes. 

Your gas control knob must be in the pilot position. Repeat this test. If it reads more than 400 millivolts, it shows you a good thermophile output for your device. If you see that the result is less than 400 millivolts, this indicates you have a bad thermopile. 

Replacement With New Thermopile 

Use a multimeter to test the resistance and voltage of the thermopile. If it is not working properly so change it with a new one.

You Can Replace Thermopiles 

Turn The Gas Supply Off: 

The first step is to turn off the gas supply to your water heater. Turn the gas on/off control knob to the OFF setting. To access the component, remove the protective cover. 

Removes Circuit Wires: 

At this point, the thermopile wires and igniter should be disconnected. It may take some twisting to get it out. Removal of the pilot tube and manifold should be done carefully. Connections come loose easily, make sure you use the right size tools for the job. During this step, be careful. You don’t want to mess up any wires or tubes. 

Remove The Manifold Door: 

There are two screws that secure the manifold door assembly. You will need to remove these screws to gain access to the thermopile outside of this door. 

Once the door is open, be prepared to note where the tubes and wires fit and attach to the manifold door. You need to remember their exact location when you replace the thermopile.

After passing through the door, move the burner assembly out of the chamber. You will now have access to Thermopylae. 

Pull Off Pilot Assembly And The Thermopile Wire: 

You will see the manifold door retaining clip. Go ahead and remove it. Remove the screws holding the shield and pilot assembly in place. Disconnect the thermal switch wiring. After following these steps, it is possible to pull the pilot assembly out through the manifold easily. You may have to twist it around to get it to come out. 

Replace The Old Thermopile Wire With A New: 

Strip the new wire to connect the thermopile. Thread it into the manifold door. Make sure you sit it all the way down. Once it’s in place, secure the manifold door retaining clip back where you found it. All you have to do is click on the position. 

By The Manifold, Door Remove The Wires: 

Feed the alternate thermopile wire and pilot tube into the manifold port. Don’t bend the pilot tube while doing this. You may have some trouble reassembling it when you’re ready.

Enter The Component Block Of The Manifold: 

Avoid pinching the wires while inserting the component block, and return the pilot assembly to shield their original positions. 

When you insert the component block, avoid pinching the wires. The ingredient block will slide into place when you feed through the door. 

Make sure the insulation of each wire is aligned with the component block.

Reattach The Thermal Switch Wires: 

Place the shortest wires on the left. Check to see if the gasket for the manifold door is damaged. Do not reinstall a damaged gasket. You have to change it. Since you are already working on this part of your water heater, you may want to take the opportunity to do it. 

After Replacing The Manifold Door Make It Secure: 

There is a burner plate with a tab at the base. Insert it into the slot which is on the bracket. This bracket is for the burner at the base of the chamber. 

When it connects with the bracket you should hear and feel it. It should sit there safely. After placing the burner, move it from left to right to ensure that it does not move.

If you are able to move the entire burner, it is not seated properly. You have to fix this problem. Now, you have to put the manifold door back in place using the screws you removed. 

Reattach The Pilot Tube And Start The Gas Flow: 

First, reconnect the pilot tube. After it does the same act with the manifold tube. Put the wiring back into position for the thermopile. 

Reconnect the wiring to the igniter. Turn on the gas and set the thermostat knob to the pilot. Press the knob. Press the switch which will ignite the flame at the same time. 

Press until you see a blue flame. You should not smell any gas. If there is any smell, it means your pilot tube is not in place. It needs to sit correctly before going any further. 

Adjust The Temperature: 

If there is no gas smell, the knob is now seated correctly. It’s time to set your desired temperature. Keep holding its knob down for a minute. Wait to let go until the control light starts blinking. Now, set the desired temperature. 

Make Sure There Is No Gas Leakage:

You may not smell gas in the air, but you still want to be sure. You can confirm if you don’t have gas leaks with a soap test. Make a solution with soap and water and pour some around connections and valves. Check to see if there are bubbles. If you see bubbles, try reconnecting the lines. If this does not work, turn off the gas and seek professional help. 

Can You Deal With Thermopile Low Voltage? 

If you follow the step-by-step troubleshooting guide, the problem will be solved quickly. But remember that problem will be different for everyone. 

A few minor mistakes, twisted furnace setting, right adjustment, installation mistakes etc. can cause voltage problems in the thermopile. 

So remember, a healthy thermocouple reading should be between 650-850 millivolts. If you fix every possible step, replace the old unit, and are still experiencing a voltage problem, contact a professional. 


For everyone, it is important to know about the working of thermopiles and their voltage for better performance. After identifying the reasons and taking steps for appropriate troubleshooting, anyone can fix the low thermopile voltage problems. 

Always check the temperature gradients, connections, and environmental factors and pay attention to the circuit layout. If there is a need to replace an ageing or damaged thermopile to maintain optimum voltage make sure good quality gadget. 

Remember, many factors affect the thermopile current or its voltage reading. You can confirm the thermopile voltage low using a multimeter. 

If the low voltage persists for hours, go through our troubleshooting steps, such as repairing cold junctions, testing the unit, and replacement. 

Professional help is required only if none of the correct steps works in your favor. 

FAQs Related To Thermopile Voltage Low 

Why is the thermopile voltage reading low?

A low thermopile voltage reading can have many causes, including loose connections, insufficient temperature differential, thermal insulation problems, environmental factors, ageing or damaged thermopile, or circuit misconfiguration. 

How can you address your thermopile low voltage? 

Check all securing connections and ensure an adequate temperature gradient. Inspect insulation, address environmental factors and review the circuit configurations. 

How long can a thermopile last? 

In general, the age of a thermopile is not fixed. If the unit is used and maintained properly, it can last for years or decades. 

How much a thermopile take time to heat up? 

Typically, a thermopile takes 30-60 seconds to heat up to show a proper reading. But you should make sure that the pilot valve is open, and the flame should go out when you press the start button.

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