What happens when a thermocouple goes out?

What happens when a thermocouple goes out?

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.

Does cleaning a thermocouple work?

The best way to clean your thermocouple is to use either a piece of steel wool or the coarse side of a sponge to gently clean off any soot or other remnants. You can use a pencil eraser to clean between the threads of the screw that connects the thermocouple to the control valve of your system.

Can a thermocouple work intermittently?

a safety device that has started to go bad, or has failed permanently. In this client’s case, the thermocouple was initially working intermittently, and then finally failed. This allowed the gas to flow long enough to heat up the thermocouple and generate some electrical current flowing back to the gas valve.

Will a pilot light on a thermocouple go bad?

A thermocouple senses the heat of the pilot and allows gas to flow to the burner. A bad thermocouple will shut off gas to both the pilot and the burner so the pilot light won’t stay lit.

What causes a thermocouple to fail?

METAL FATIGUE 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. If thermocouples start to give out unusual readings, it may be suffering from metal fatigue.

How long should thermocouple last?

In effect, new thermocouples were installed into contaminated tubes, causing the degradation of the sensors and generating greater than a 100°F shift in accuracy. In this scenario, thermocouple life, which should have been close to one year, was shortened to within a week.

Should the flame touch the thermocouple?

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.

Will a pilot stay lit with a bad thermocouple?

How do I know if my thermocouple is working?

If the thermocouple is working, you should be able to measure 30 to 40 millivolts of voltage at the connection end of the tube when the pilot flame is on. You can test this yourself using a multimeter, but you may need a helper to keep the pilot flame burning while you do it. Start the test by unscrewing the thermocouple from the gas valve.

Can a bad thermocouple affect the readings on a furnace?

And the worst part is that you can have a bad thermocouple without even knowing. Therefore, inspecting and testing your thermocouple should be part of your furnace maintenance. Be sure to inspect before you test, however, to ensure that there are no obvious problems that could affect the readings from testing!

What are the symptoms of a bad thermocouple or thermistor?

Symptoms of Bad thermocouple or dirty thermistor on gas fired equipment: Short cycling or unexplained on-off cycling of heating equipment has also been traced (by one reader) to a dirty or failing thermocouple (possibly the reader meant a dirty thermistor).

What should I look for when choosing a calibration thermocouple?

Always double check to make certain that the thermocouple that you have in question is of the same match, style and calibration type for the application / equipment that you are using. For example; a J type calibration thermocouple cannot be used on a specific application calling for a K type thermocouple.