What does a thermocouple do in a gas fireplace?

The thermocouple on your gas fireplace is a heat-sensitive device that keeps the pilot gas tube open while the pilot is lit. It does this by generating a small electric current -- on the order of 10 to 30 millivolts -- as a signal to the gas valve.

Also to know is, what happens when a thermocouple goes bad?

If the appliance has a thermocouple, the problem may be a faulty thermocouple. The thermocouple, which operates as a safety device, turns the gas supply off when the pilot light goes out. When a thermocouple fails, the pilot light won't stay lighted. A burned out or broken thermocouple should be replaced.

Furthermore, how long should a thermocouple last? The thermocouple can do this because, in its probe, it contains two different metals, and a voltage is generated when one of them is heated. This is the result of a phenomenon known as the Seebeck Effect. Nothing lasts forever, and when the thermocouple wears out, the pilot won't stay lit and your appliance won't work.

Also know, how long does a thermocouple last on a gas fireplace?

Thermocouples can last several years, but they don't typically last as long as the furnace itself. If the pilot remains lit, but the main furnace doesn't stay lit, it's time to replace the thermocouple. Replacement thermocouples are in stock at most hardware and home improvement stores.

How do I know if my thermocouple is working?

Select the ohms or resistance option on your multimeter. Place one test lead on the side of the thermocouple and the other to the end that screws into the gas valve. If the thermocouple has proper continuity, a small resistance reading should be visible on the multimeter.

What causes a thermocouple to fail?

Changes in temperature can cause regular expansion and contraction in metal, which will cause thermocouples to weaken over time. After enough time, metal fatigue can cause a thermocouple to break.

Are thermocouples universal?

Universal Thermocouples. Universal thermocouples, as the name implies work on most water heaters. They are available online and in home supply stores for a reasonable cost. The length and the thread type are the two concerns when purchasing one.

What does a thermocouple look like on a gas fireplace?

The thermocouple on your gas fireplace is a heat-sensitive device that keeps the pilot gas tube open while the pilot is lit. The thermopile is a related device that you should test at the same time -- its function is to open the gas to the burners.

How do you troubleshoot a thermocouple?

Method 1 Turning on the Pilot Light

1. Locate the pilot light controls on the gas valve.
2. Turn the pilot light on for 30 seconds.
3. Release the button to see if the pilot light goes out.
4. Turn off the gas supply to test the thermocouple again.
5. Count to 20 and wait for the pilot light to go out.

Why does my thermocouple keeps burning out?

1) Faulty Thermocouple. If your pilot light won't stay lit, the thermocouple is very likely the culprit. The thermocouple is the copper rod the pilot flame directly hits. Sometimes it's referred to as the "flame sensor." It's a safety mechanism that shuts the gas off should the pilot go out.

What does a thermocouple look like?

The thermocouple looks like a piece of metal tubing smaller than a soda straw. To find it, first locate the gas control box. This is the box that the main gas line enters, where you turn the gas on in the furnace. The other end of the thermocouple sits in the flame of the pilot light.

Can you clean a thermocouple?

If the Thermocouple is faulty it will cause the unit to shut down. How to clean? Remove Thermocouple from pilot assembly, using steel wool or emery cloth to lightly clean the tip removing any soot or build up that might have accorded due to an improper pilot flame.

What happens if you wire a thermocouple backwards?

ARE YOUR THERMOCOUPLE WIRES BACKWARDS? If your thermocouple leads are backwards, then the measured temperature will be shown as varying in the opposite direction from ambient (e.g. if the instruNet terminals are at 25°C and the thermocouple is at 35°C, and the leads are backwards, then instruNet will report 15°C).

Why does my pilot light keep turning off?

Usually, a problem with the thermocouple causes the pilot light to go out. The thermocouple is the small copper rod that the pilot light hits. The thermocouple's job is to shut a gas safety valve if the pilot light goes out. That's important because gas is always being supplied to the pilot to keep the flame lit.

How much does it cost to replace a thermocouple?

Thermocouple Replacement - $20-$150 Calling a professional plumber to install a new thermocouple should only be up to $150. If you do the work yourself, you will only pay the price of the part which is about $20.

How do you adjust a thermocouple?

To adjust the thermocouple, you must tighten the thermocouple nut with a wrench. Take care not to apply too much pressure to the nut -- just tighten it slightly. Then try lighting the pilot. If the pilot won't stay lit, replace the thermocouple with a new one of the same type.

How close should the thermocouple be to the pilot light?

about 1/2 inch

How do you test a gas valve?

How to Check the Furnace Gas Valve With a Multimeter

1. Turn off the furnace at the wall control.
2. Take out the bolts in the service panel on the side of the furnace using a nut driver.
3. Pull the wires off the gas valve terminals.
4. Turn the test control on the multimeter to "mV," which stands for millivolt.

Why does my gas fireplace go out after a few minutes?

1) There's enough gas flow to maintain the pilot light, but after you burn the larger flame a few minutes pressure drops too low to support the larger flame and it goes out. Pressure builds in the header while you scratch your head, allowing you to run it a few mintues again until pressure drops too low again.

Why would a gas fireplace keep going out?

My first guess would be the thermocouple is bad, or going bad. The thermocouple is a small device that generates electricity from heat, they are used in gas furnaces and such to shut off the gas in case the pilot goes out (so gas doesn't continue to flow and fill the room).

Should the pilot light always be on in a gas fireplace?

Electronic ignition is when the pilot light on a gas fireplace/insert/stove is only running when the fireplace is on, this means that the unit is likely to have a battery backup as well. A standing pilot is always on, always using a small amount of gas to run constantly unless the gas is physically turned off.

How do I know if my gas fireplace is working?

You should:

1. Inspect the glass doors for cracks or latch issues.
2. Check that gas logs are in the proper position.
3. Turn gas off at the shut-off valve and test the igniter.
4. Ignite the fire and look for clogged burner holes. If present, turn off gas and clear obstructions with a pin or needle.