How to Test a Gas Fireplace Thermocouple
- Locate Gas Valve and Pilot Assembly. The thermocouple will resemble a long copper wire running between the pilot light and the gas supply valve.
- Hold Pilot Open to Heat Thermocouple. Push in the control valve and light the pilot flame. ...
- Watch Pilot with Main Burners On. Even if the pilot lights, a draft may have diverted it from the thermocouple. ...
How to test a thermocouple on a gas refrigerator?
MultiMeter Thermocouple Test Procedure
- First, remove the thermocouple.
- Secondly, turn on the meter and set it to Ohms. ...
- Thirdly, start the flame and put the tip of the thermocouple in the fire.
- Next, ensuring the tip is nice and hot from the flame, take one lead from the meter and put it on the shaft of the thermocouple and the other lead ...
How to measure temperature with a thermocouple?
- Measure the “VD” millivoltage as shown above.
- Measure the actual temperature of the reference junction with a thermometer.
- Go to the table for the thermocouple being used and look up the millivoltage produced at that temperature.
- Add that millivoltage to the millivoltage measured as “VD” to get a total.
How to measure your fireplace?
Measure the front opening of your fireplace. 2. Measure the back width of your fireplace. 3. Measure the depth of the floor from back wall to the front of your fireplace. 4. Measure the inside height of the fireplace from the floor to the lowest point inside the fireplace. Once you have completed measurements, use our gas log or fire glass ...
How to test a thermocouple with meter?
- Method 1: Resistance Test. Carefully remove the faulty thermocouple from the gas appliance. ...
- Method 2: Open Circuit Test. In this test, the same setup as above will be used, but instead of measuring resistance, voltage generated by the thermocouple will be measured and ...
- Method 3: Closed Circuit Test. ...
How do you check if a thermocouple is working?
1:473:21How to test a thermocouple with a meter (grounded & ungrounded)YouTubeStart of suggested clipEnd of suggested clipIf I take my wire and attach it to anywhere along the sheets of the probe. I attached to the sheathMoreIf I take my wire and attach it to anywhere along the sheets of the probe. I attached to the sheath and I'm getting continuity this is a grounded thermocouple if this was an ungrounded thermocouple.
How long does a thermocouple last on a gas fireplace?
Thermocouples can last up to 10 years if properly installed and maintained, while furnaces can last 15-20 years, although either may wear out sooner in multifamily units.
How do I know if my thermocouple is broken?
After about a minute, when you're sure the probe has gotten hot, place one lead on the shaft of the thermocouple and the other lead on the connector. If the reading is less than 25 millivolts, the thermocouple is bad and needs to be replaced.
How do you read a thermocouple with a multimeter?
0:183:10How to test a thermocouple with meter - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo why not show you how to do it with the multimeter. So the first thing you want to do is go toMoreSo why not show you how to do it with the multimeter. So the first thing you want to do is go to your volt setting. And you want to be on DC milliamps. So I'm going to click that. And see the symbol
How do I know if my thermocouple is bad on my gas fireplace?
2:313:43Fireplace How To: Testing A Thermocouple - YouTubeYouTubeStart of suggested clipEnd of suggested clipYou should replace the thermocouple. So to recap the readings to look for are 8 to 30 millivolts.MoreYou should replace the thermocouple. So to recap the readings to look for are 8 to 30 millivolts. And if the readings are less than 7million. You should replace the thermocouple.
How much does it cost to replace a thermocouple in a gas fireplace?
between $150 and $250When replacing a thermocouple or thermopile with the help of a professional, you can expect to pay between $150 and $250.
Can I bypass a thermocouple?
Realistically, you have just disabled the thermocouple, but you can also reach in and unclip it from its holding bracket where it meets the pilot light. In most cases it will be held on with a gravity clip, but some are held on with a screw that must be removed with a small screwdriver.
How do you clean a thermocouple on a gas fireplace?
How to Clean a Thermocouple on a Gas Fireplace [3 Steps]Step 1: Leave the gas to cool first if it has been burning.Step 2: Polish the thermocouple.Step 3: Blow it out.Step 4: Light the gas.
What happens when thermocouple goes bad?
This means that if the thermocouple goes bad, there is no way of detecting if the pilot light is burning or not. And when the pilot light goes out, you will not have hot water supply in your plumbing system. To test if the problem is with the thermocouple, try to relight the pilot.
How does a thermocouple work on a gas fireplace?
When turned on, the pilot in a gas stove generates heat, which travels through a thermocouple. As the heat reaches the second junction of the thermocouple, it generates electrical voltage. The fireplace uses this voltage to open the gas valve, allowing gas to flow out and start a fire.
Should thermocouple be in pilot flame?
The pilot flame should touch the thermocouple at a specific level. If the flame is blue and weak, and barely reaches the thermocouple, it needs to be stronger. If it extends well above the thermocouple, it's too strong.
What resistance should a thermocouple read?
A thermocouple should exhibit very low resistance. Attach the negative lead to the red wire, and the positive lead to the yellow. In this case, the reading will be about three ohms.
How do you clean a thermocouple on a gas fireplace?
How to Clean a Thermocouple on a Gas Fireplace [3 Steps]Step 1: Leave the gas to cool first if it has been burning.Step 2: Polish the thermocouple.Step 3: Blow it out.Step 4: Light the gas.
How much does it cost to replace thermocouple?
Thermocouple – $20 to $150 The thermocouple is an apparatus that senses whether the pilot light is lit and triggers the gas control valve. Repairs typically cost about $150 to have it done professionally, though a new thermocouple itself only costs about $20 on average.
How do thermocouples fail?
After enough time, metal fatigue can cause a thermocouple to break. Thermocouples that are regularly exposed to extreme heat stress or extreme conditions are more likely to go through metal fatigue. If thermocouples start to give out unusual readings, it may be suffering from metal fatigue.
Why does the pilot light on my fireplace keep going out?
The Fix: Pilot Light to Gas Fireplace Won't Stay Lit This can be an indication that your fireplace thermocouple is either bad or worn out. However, if your pilot is lit but the gas fireplace isn't, then there's probably a problem with your thermopile.
How to test thermocouple with multimeter?
How to Test a Thermocouple with a MultiMeter. If you test the thermocouple with the multimeter and you get a reading above 25, then you have another issue. Importantly, always make sure the tip of the thermocouple is directly in the pilot flame. If the tip is in the flame, you have held the nob on the gas valve down for longer than a minute, ...
How to read infinity on a thermocouple?
First, remove the thermocouple. Secondly, turn on the meter and set it to Ohms. Touch the two leads together from the meter, and you should get a reading close to zero. With the leads apart, you will read infinity. That is simply a test to check the meter for continuity. Finally, NOW TURN THE METER TO VOLTS.
How many millivolts should a pilot gas valve be?
Finally, if the reading is less than 25 millivolts replace the thermocouple as most standing pilot gas valves need 25 or more millivolts to keep the pilot flame lit. The thermocouple millivolt range should be above 25 millivolts. If so then it is good.
What is the tip of a thermocouple called?
That provided a means of proving the main burners would ignite when the main valve opened. The tip of the thermocouple is called the hot junction and is where the two dissimilar metals join. A weld joins the two metals. The other part of the thermocouple tip is called the cold junction.
What is a thermocouple?
A thermocouple is a safety device for a standing pilot gas system. Originally, it had a ratio of copper and nickel and was labeled a Coppel ( Copper/Nickel) element. Thomas Seeback discovered it in 1821. In the early 1900s, Honeywell applied it to the safety gas valve.
What happens when the heat hits the hot junction or tip of the thermocouple?
When the heat hits the hot junction or tip of the thermocouple, it produces millivolts. This fractional voltage energizes a small solenoid designed for millivolts. As long as the solenoid is energized, the pilot valve inside the gas valve remains open. That allows the main valve inside the gas valve to feed the main burners with gas.
How many cubic feet of gas is 1 CCF?
Number of British Thermal Units used. 1 CcF is equal to 100 Cubic Feet of Gas. This is how most gas companies will bill you. If your gas company uses Therms then input the number of Therms on your gas bill. 1 Therm = 1 CcF.
Where should the thermocouple sit in a fire?
Even if the pilot lights, a draft may have diverted it from the thermocouple. The thermocouple should sit in the top third of the blue cone of fire. Watch the flame during operation to see if it strays.
What does a thermocouple look like?
The thermocouple will resemble a long copper wire running between the pilot light and the gas supply valve. The pilot light usually looks like a narrow bent tube cut at a shear angle. Shut off the furnace gas to remove and clean the thermocouple if it is covered with soot.
How to check if thermocouple is at fault?
To double-check that the thermocouple is at fault, look at the dial to locate a position labeled “Off.” Spin the dial to shut off the gas supply. If this isn’t possible, follow the metal pipe leading into the pilot light controls. It will have a small valve on top of it. Turn the valve counterclockwise to stop the flow of gas.
Where is the thermocouple on a gas thermostat?
Locate the thermocouple on the gas control thermostat. The gas control thermostat will be on the outside of the gas tank, possibly on a nearby wall. Look for a flexible tube plugged into the side of the thermostat. It is often colored silver or red.
How to remove thermocouple from thermostat?
Remove the thermocouple with a wrench. Go back to the thermostat and locate the metal nut holding the thermocouple in place. Use a 7⁄16 in (11 mm) wrench to rotate the nut counterclockwise and free the thermocouple. Turn on the multimeter.
What does it mean when a thermocouple is white?
If your thermocouple is coated with a white, chalky material, this may indicate it's not functioning properly. [15]
How to measure resistance?
For the test, the type of multimeter with red and black clamps is easiest to use. Flip on the multimeter’s power switch. Spin the settings dial to change the measurement to Ohms, represented by the horseshoe-shaped symbol . This is used to measure electrical resistance.
What is a thermocouple?
A thermocouple is a safety device that helps control the gas supply in gas-heated furnaces. When it stops working, the furnace’s pilot light also turns off. For a basic test, attempt to turn on the pilot light again. If you’re still unsure or don’t have a working pilot light, test the thermocouple with a multimeter.
How to test a multimeter?
Test the multimeter by holding the leads together. Hold the black and red clamps, or leads, apart. When you point them in opposite directions, the meter should stay to the left at infinity. Bring the leads together and watch as the meter changes to 0.
How to inspect thermocouple?
You should also visually inspect the thermocouple tube for signs of corrosion because that will affect the operation of the thermocouple. Use a wrench to make sure the nut is tightly connected to the gas valve. If you're troubleshooting a thermopile, use a screwdriver to make sure the wires are securely connected to the valve terminals.
How to tell if a thermocouple is bad?
The definitive way to identify a bad thermocouple is to test it using a multimeter with alligator clips on the leads. Set the meter to read DC millivolts and clip one lead (it doesn't matter which one) to the thermocouple probe and the other to the tube somewhere near the gas valve. Turn on the pilot, let it burn for 30 seconds and note the reading. Anything less than 25 mV indicates a faulty thermocouple.
How does a thermocouple work?
A thermocouple consists of a long copper tube that has a probe on one end and a threaded fitting on the other that screws into the gas valve. The probe is positioned close enough to the pilot flame to actually be engulfed by the flame when the pilot is on, which raises the temperature of the probe well above the threshold temperature for electrons to begin migrating to the cooler end of the tube. This occurs by virtue of a phenomenon known as the Seebeck effect, whereby an electric potential is generated between dissimilar metals when there's a large temperature difference, and the thermocouple probe and tubing are indeed made of different metals.
What happens if the thermopile drops to zero?
If it drops to zero, the thermopile has a short and needs to be replaced. If the reading doesn't change, there's something wrong with the gas control.
What happens if the thermocouple isn't working?
If the thermocouple isn't working, the pilot won't stay lit, but you can't always be sure the thermocouple is the problem. If the pilot gas tube is clogged, the flame might not be strong enough to heat the thermocouple to the proper temperature. Light the pilot and observe the quality and size of the flame. It should be mostly blue, burn steadily and be large enough to engulf the thermocouple probe. If it's yellow or orange, undersized and unsteady, the pilot tube is probably clogged, and it needs to be cleaned.
What is the function of thermocouple?
The function of the thermocouple is to send a signal to the gas valve to stay open while the pilot is on . Many contemporary gas appliances have ...
What is the probe on a thermopile?
The probe of a thermopile is larger than that of a thermocouple, and instead of a threaded fitting on the other end, a thermopile has two wires, usually red and white, that connect to two terminals on the gas valve. The terminals are labeled TP and TP/TH, as illustrated at My Gas Fireplace Repair.
How to Test Thermocouple on Gas Fireplace?
The thermocouple is a protection device that controls the gas supply to the gas-heated fireplace. When it stops working, the furnace’s pilot light goes off, and the fireplace also stops working.
How to test for bad thermocouples?
This is the most reliable way to test. To identify bad thermocouples in this test, use a multimeter with a lead alligator clip. Set the meter to read dc millivolts. Now carefully clip one lead to the thermocouple probe, and the other to the tube near the gas valve.
What do gas fireplace soldiers use?
Gas fireplace soldiers primarily use thermocouples and thermopile devices to generate electricity. Thermocouples act as a sensor for gas flow. It supplies gas to the pilot lightthrough a gas valve.
Why is my thermocouple not working?
It may be that the pilot gas tube is closed. If this is the case, the flame will not be strong enough to heat the temperature to the right temperature.
How to tell if a thermocouple is closed?
First, illuminate the pilot and observe the size and quality of the flame. It should be mostly blue. Will burn slowly and will be large enough to attach the thermocouple probe. If it is not yellow or orange, irregularly shaped, and unstable, the pilot tube is closed. Clean it.
What is a thermocouple?
The thermocouple is a heat-sensitive device placed on a gas fireplace. When the pilot is turned on, it sends a small electrical signal to the gas valve and keeps the gas valve open. This is an essential part of your fireplace, which does not burn the pilot if it fails, and when the pilot fails, the fireplace also stops working.
What is the purpose of a thermocouple?
This voltage is mainly used to control the main gas. This voltage produced is measured in millivolts. Its main power is the pilot light.
How to replace thermocouple?
The only tool you need to replace a thermocouple is a wrench. Use it to unscrew the connector that holds the thermocouple to the gas valve, then unhook the probe from its clip and pull out the entire thermocouple assembly. Before you do this, be sure to turn off the line valve on the gas supply.
What is a thermocouple?
All gas appliances with standing pilots, such as furnaces and water heaters, have a thermocouple. It's a cylindrical probe about 4 inches long and a quarter to a half inch in diameter that's attached to a 1- to 2-foot length of copper tubing. The probe is positioned next to the pilot opening so that its tip is in the flame when the pilot is on. The other end of the tube connects to the gas valve by a threaded connector.
How does a pilot flame probe work?
The tip of the probe contains a heat-sensitive material that generates a small electric voltage – around 25 millivolts – when it's heated by the pilot flame. The voltage sends a signal to the gas valve to stay open. Without this signal, the valve closes automatically to prevent the release of unburnt gas. When you light the pilot, you usually have ...
How long does it take for a thermocouple to heat up?
When you light the pilot, you usually have to hold in the gas valve manually for about 10 seconds to give the thermocouple time to heat up. Once it has reached the required temperature, you can release the valve control and the pilot will continue burning.
How long does a thermocouple last on a gas furnace?
The thermocouple lasts for 10 years or more, and when it fails, the pilot won't stay lit and the fireplace won't work.
How long is a spherical probe?
It's a cylindrical probe about 4 inches long and a quarter to a half inch in diameter that's attached to a 1- to 2-foot length of copper tubing. The probe is positioned next to the pilot opening so that its tip is in the flame when the pilot is on.
Can you replace a fireplace with a voltmeter?
Replacing it is a relatively simple job that you can accomplish with a wrench. Before you replace it, though, it's a good idea to test it with a voltmeter to make sure it's actually malfunctioning. If it checks out, the problem with your fireplace could be a blockage in the pilot tube or a faulty gas valve. Advertisement.
