Dirty or Damaged Thermocouple Explains Why Pilot Light Keep Going Out. A faulty, misaligned, dirty, or damaged thermocouple is often the culprit behind your pilot light going out. The thermocouple is an automatic safety shutoff device that prevents the gas valve from opening if the pilot light is out.
Dirty Thermocouple
If it's filthy shut your gas off so that the unit can cool down, then gently clean it by carefully rubbing it with fine grain sandpaper. When you're done, simply turn the gas back on and light the pilot again. If dirt or grime was the issue, your light shouldn't go out again!
Unless there is something severely wrong with your furnace, there is nothing that any thermostat can do that will put out your pilot light.
There are two main reasons why your thermocouple might fail. The first is age. For the most part, your thermocouple is more likely to fail once it takes on some wear and tear. Additionally, thermocouples can sometimes fail due to manufacturer defects.
If your gas fireplace pilot light keeps going out, you may have a problem with faulty pilot controls. The pilot control failing due to age or a mechanical issue can cause your pilot light to keep going out and prevent it from being relit.
Pilot lights will occasionally go out. Sometimes the cause is easily resolved, such as running out of propane or turning off the gas. However, if the pilot light needs to be relit more than once per season, it should be inspected by a qualified service technician.
Common Signs of a Failing Thermocouple
Here are some common indicators: Difficulty Lighting the Fireplace: If you struggle to light your fireplace, or if it takes several tries to keep the pilot lit, it could suggest that the thermocouple is not sensing the flame correctly and is failing to keep the gas supply open.
Thermocouples are prone to corrosion and damage, especially if they are exposed to a lot of dust and grime. If you can access the thermocouple, look for visible signs of wear and tear, such as bends, kinks, or discoloration.
If the pilot flame ignites but goes out after you release the gas control knob, the cause may be a dirty or defective thermocouple. If the gas is on but the flame will not ignite at all, a pilot tube obstruction is the most likely issue. Remove the pilot tube from the gas valve and spray compressed air to clear it.
Sometimes sensors can break or degrade in harsh environments. You might be suffering from intermittent thermocouple failure or instruments might be showing “Open Circuit”.
So you've checked your pilot light and even reset it, but still, it wont 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.
A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.
Gently scrub any corrosion or oxidation on the thermocouple tip using very fine steel wool or a green cleaning pad. Take care not to bend or damage the internal sensor.
Take a soft brush such as an old toothbrush and gently remove any visible debris from the pilot orifice, flash tubes and ignitors. Next, insert a sewing needle or thin wire into the pilot orifice, the flash tubes and the holes in the ignitors, as well as in the burners, wiggling it gently to dislodge any debris.
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.
To determine if your thermocouple only needs a good cleaning or requires replacement, it will come down to how often your pilot light is going out. If you're experiencing pilot light outages every few days or have a water heater that is over 10 years old, you'll do better by replacing the thermocouple.
Pilot Light Won't Stay Lit
The issue could be: A dirty tube: If the pilot light tube is dirty, it can put out the light over time. You'll need to clean it with something abrasive to get it working again. Not enough gas: Sometimes, the gas valve will leak, or something else prevents gas from getting through the line.
Symptoms Pilot won't light. Pilot lights but burner won't. System lights, but goes out after a while.
The Pilot Lights But Won't Stay Lit
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.
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.
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.
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.
Common Gas Fireplace Issues and Repair Options
Relighting is typically inexpensive unless the thermocouple requires replacement, which can range between $120 and $300.
Failed Thermocouple Symptoms
You're looking for a few things. The first is signs of contamination on the tube, which can include discoloration, cracks, or pinholes. Next, check the wiring for any signs of wear or corrosion like missing insulation or bare wire.