Question: How Do You Know If You Have A Bad Thermocouple?

Will pilot stay lit if thermocouple is bad?

The thermocouple, which operates as a safety device, turns the gas supply off when the pilot light goes out.

It consists of a heat sensor connected to a solenoid; when the sensor is not heated by the pilot flame, the solenoid closes the gas supply line.

When a thermocouple fails, the pilot light won’t stay lighted..

How do you test if a 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.

How do you fix a thermocouple?

Replacing a ThermocoupleShut off the gas and electrical power to the furnace.Remove the furnace’s access cover.If the furnace has been running, wait 30 minutes for the thermocouple to cool completely.Unscrew the nut that holds the thermocouple end fitting into the gas control valve, using an open-end wrench.More items…

Are all thermocouple the same?

A thermocouple uses two types of metal to create an electrical current that the gas valve can sense. … From an operational perspective the thermocouples for a water heater are all pretty much the same. However, there are two variables, the length and the fittings used to install them, see below.

What happens if you over tighten thermocouple?

Over-Tightening When screwing the thermocouple into the gas valve be sure to not over tighten it. This can cause the thermocouple to either become damaged or it may damage the sensor in the gas valve. … The thermocouple can be cracked or broken if not treated with care.

What causes a thermocouple to go bad?

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.

What does the 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 bypass a thermocouple?

Harley said: Bypassing the thermocouple would make it no more dangerous than any propane grill. It’s not going to make it explode. The only thing it would prevent is losing a tank of propane into the atmosphere if the flame happened to go out because the valve wouldnt close.

How much should you tighten a thermocouple?

Proper tightness should be finger tight plus ¼ turn. Inspect thermocouple to ensure that it is fully engaged into pilot bracket. Adjust tip of thermocouple to be fully engulfed by pilot flame.

How long does a thermocouple last?

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.

Can you replace a thermocouple yourself?

It’s easy to replace and a new one costs $5 to $10. Rather than trying to unfasten the thermocouple inside the water heater’s burning chamber, it’s easier to remove the whole burner and thermocouple assembly. … Then unfasten the three nuts that hold the thermocouple and the two gas tubes to the valve.

Is thermocouple a sensor or a transducer?

Common Sensors and TransducersQuantity being MeasuredInput Device (Sensor)TemperatureThermocouple Thermistor Thermostat Resistive Temperature DetectorsForce/PressureStrain Gauge Pressure Switch Load CellsPositionPotentiometer Encoders Reflective/Slotted Opto-switch LVDT3 more rows