Once you've located the thermocouple, do a visual inspection. You're looking for a few things. The first is signs of contamination on the tube, which can include discoloration, cracks, or pinholes.
A pilot light may not light due to a buildup of soot and carbon on the thermocouple. Cleaning the thermocouple can fix the issue and extend the life of the device. Locate the pilot assembly and find the thermocouple. Usually, the tip of the thermocouple touches the pilot light.
For a bad thermocouple, you will normally see a high temp displayed, and the controller will immediately go into cool down mode. You are showing heat up mode, and erratic temperature displays.
The best way to verify that you need a new thermocouple is to see if your pilot light is lit. If the pilot light can't hold ignition, that means either a problem with the gas supply or, more likely, the need for thermocouple replacement.
Clean the thermocouple - using the emery cloth sandpaper, sand the ends of the thermocouple and then give it a finishing touch with the lint-free cloth.
Can I clean my thermocouple instead of replacing it? If the thermocouple tip is only lightly corroded or covered in dust/debris, cleaning may restore functionality. But if you find any cracks, bent wires, or significant corrosion pitting on inspection, replacement is the safest option.
The thermocouple is a safety device designed to shut off the gas valve if the pilot light goes out. Although, if your thermocouple is old, worn, damaged, wrongly positioned, or malfunctioning, it could have wrongly shut off the gas valve and prevented your pilot light from staying lit.
Here at Boss Plumbing, we highly recommend you not try to replace the thermocouple on your water heater yourself. Though not a highly complex water heater repair, it nevertheless does involve the use of gas. Thus, if you are unsure about what you are doing, one small mistake could lead to a disaster.
Overheating: Each thermocouple is designed to operate within a certain temperature range. Operating beyond this range can damage the thermocouple's materials, causing them to degrade faster than normal. Contamination: Exposure to harmful chemicals or debris can affect the thermocouple's performance.
Temperature sensor and thermocouple errors can be caused by various factors, such as mechanical damage due to physical stress, abrasion, or corrosion; electrical interference from nearby sources of electromagnetic radiation; wiring problems like loose, broken, or mismatched connections; calibration issues that cause ...
Symptoms Pilot won't light. Pilot lights but burner won't. System lights, but goes out after a while.
If finding that the thermocouple does not read, the problem is most likely a bad connection, broken wiring, or open internally within the thermocouple probe circuit.
If you can't get the flame to light at all, and you're sure the gas is on, there's probably an obstruction in the pilot tube. If the flame lights and goes out when you release the gas control knob after holding it in for the recommended 20 to 30 seconds, that's the sign of a thermocouple malfunction.
Common reasons include a nearby draft, dirt buildup, or a malfunctioning thermocouple. Another pilot light drawback is energy waste. Since the pilot light needs to remain active, your furnace is always consuming some gas. It's not a lot—usually just a few therms of gas a month–but that obviously adds up over time.
Once you've located the thermocouple, do a visual inspection. You're looking for a few things. The first is signs of contamination on the tube, which can include discoloration, cracks, or pinholes.
When you have a thermocouple that is going bad on your water heater, the most obvious sign will be a pilot light that always seems to be going out. If you light the pilot light but then find it extinguished less than a week later, you'll need to closely examine the thermocouple.
Thermocouples are relatively affordable components, typically ranging from $10 to $30, depending on the brand and quality. However, keep in mind that DIY replacement requires knowledge of furnace systems and gas connections, and improper installation can lead to safety hazards.
Yes, you can clean a thermocouple, but the task must be done with a light touch. Remove the thermocouple from the process assembly, using a steel wool or emery cloth, lightly clean the tip removing any build up. Cleaning a thermocouple is not a fix for an issue, such as inaccurate readings.
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.
Once you have replaced the thermocouple, turn on the furnace and check to see if the pilot light stays lit. If your pilot light doesn't stay lit, it may be due to something blocking the thermocouple. You can try cleaning or replacing it, but if that doesn't work, you may need to call a professional.
Cleaning the thermocouple
You can use Emery cloth sandpaper to gently clean any debris or build-up from the end of the thermocouple. If present, you should also clean off any corrosion where the power wire connects to the thermocouple terminal.
The most accurate thermocouple calibration is achieved is by using a Fixed Point cell where the thermocouple's output is measured against a number of fixed points along the International Temperature Scale developed in 1990 ITS-90 at the fixed point transition of various metals along the scale.
If you try to relight a pilot light and the thermocouple is bent in a way that causes it to not make contact with the pilot light, the flame will instantly go out when you release the pilot control knob since the probe won't detect the heat from the flame.