Why won’t my furnace’s pilot light stay lit?
The most common reason the furnace pilot light won’t stay lit. A furnace thermocouple is a safety feature that regulates gas flow to your system based on whether the pilot light is on.
Why does my furnace keep going on and off?
Situation: You turn the thermostat up, the furnace ignites and the burner comes on. The furnace stays on for a while (maybe 1 minute, maybe 10 minutes) and then goes out. The fan continues to run even though the flames and pilot light go out. Overheating. Your furnace has a limit switch that keeps it from running if the heat exchanger is too hot.
What should I do if my gas furnace is not working?
If you suspect that your furnace is not working because the burners aren’t igniting and want to try to troubleshoot the issue, check to make sure your gas line is turned on. You can usually see if things are working by turning on another gas appliance, such as your gas stove.
What causes a gas furnace flame sensor to go bad?
Possible causes: Bad flame sensor. The flame sensor tells your furnace that the gas is lit. Poor flame sensor positioning. The flame sensor might be fine, but isn’t positioned right and so cannot sense the pilot’s flame. Defective ignition board.
What causes a furnace to not stay lit?
Insufficient airflow into the furnace For the burners to ignite, they need airflow. The airflow into the furnace comes from the blower fan that draws air through the return air ducts. But if this airflow is choked off because of a clogged furnace filter or faulty blower, the burners may not be able to stay on for long.
Why does my furnace turn off after a few seconds?
A common reason a furnace short cycles is because the heat exchanger, the part that heats your air, is getting too hot due to a lack of airflow. Once the heat exchanger overheats, it trips the high limit switch, which shuts the furnace down to protect it.
Why does the flame keep turning off on my furnace?
If your furnace shuts off too often, you could have a corroded or dirty flame sensor. A flame sensor lets your system know there's a flame when the gas valve is open. If there isn't a flame, the sensor will shut off the gas valve to keep the gas from getting into your house.
What do you do if your furnace pilot light won't stay lit?
Check the Thermocouple If your pilot light won't stay alight, it might be the thermocouple. Sometimes dust buildup collects on the thermocouple and blocks the sensor. Try cleaning the thermocouple and then relighting the pilot light. If it continues to go out, the thermocouple might need to be replaced.
Why does my furnace only runs for a few minutes?
If your furnace shuts down after a few minutes, it's likely due to a faulty or unhygienic flame sensor. This crucial component intends to monitor the gas burner. Also, when a flame sensor cannot detect the burner, the furnace runs for a few moments before shutting down and restarting.
How do you clean a dirty flame sensor on a furnace?
1:053:46Furnace Cycling On and Off - Flame Sensor Cleaning - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo if you have a situation like this what you have 90% of the time is just a dirty flame sensor. SoMoreSo if you have a situation like this what you have 90% of the time is just a dirty flame sensor. So we'll go through the steps on how to clean it. So the right side of the furnace.
Why does my furnace start up and then shut off?
Having a dirty air filter in your furnace can cause short cycling. While a faulty flame sensor will lead to an immediate shut-off, a dirty filter will allow your furnace to run for several minutes and then shut down. You might notice that the air being pumped out of the heat grates is significantly hotter than normal.
How do I stop my furnace from short cycling?
0:424:25[5 Tips] How to Prevent Your Furnace from Short-Cycling - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo to fix this issue shut off your thermostat. And open up the furnace. And then replace theMoreSo to fix this issue shut off your thermostat. And open up the furnace. And then replace the batteries on the thermostat.
How do I know if my furnace is short cycling?
If your furnace turns on and off repeatedly for short bursts of time, not allowing the house to reach its proper temperature, it is short-cycling.
How do you clean a dirty thermocouple?
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.
How much does it cost to replace thermocouple?
Thermocouple – $20 to $150 The thermocouple is an apparatus that senses whether the pilot light is lit and triggers the gas control valve. Repairs typically cost about $150 to have it done professionally, though a new thermocouple itself only costs about $20 on average.
How much does it cost to replace a thermocouple on a furnace?
$150 to $250Thermocouple Replacement Replacing a thermocouple costs $150 to $250, mostly due to labor time. On older models without an ignitor, it checks to make sure your pilot light is lit. If it's not, it'll shut the gas off.
How do I stop my furnace from short cycling?
0:424:25[5 Tips] How to Prevent Your Furnace from Short-Cycling - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo to fix this issue shut off your thermostat. And open up the furnace. And then replace theMoreSo to fix this issue shut off your thermostat. And open up the furnace. And then replace the batteries on the thermostat.
What is considered short cycling for a furnace?
A furnace “short cycles” when it turns off before reaching the desired temperature. This means that if your thermostat is set to 72 degrees, the furnace may shut down at 65 or 68 degrees, but will never reach 72 degrees. Short cycling can also be used to describe a furnace that turns on and off too often.
How do I fix my short cycling nest?
Here's how to fix your Nest thermostat:Turn power off to your furnace.Remove the Nest from the wall (if you haven't already).Replace the red and white wires to their original locations (if you haven't already).Remove the Yellow (Y1) wire and tuck it away safely.Put the Nest back on your wall.More items...•
What causes a furnace to overheat?
Dirty filters, closed or blocked vents and other blockages in airflow are common causes of an overheated furnace. A bad limit switch. The limit switch may be bad and need to be replaced. Bad thermostat. Your thermostat may be incorrectly telling your furnace that your home is warm enough, which shuts off the burners.
Why does my furnace have a bad flame sensor?
Possible causes: Bad flame sensor. The flame sensor tells your furnace that the gas is lit. Without this device, your furnace would simply continue to allow gas to flow into your home, even when the pilot light was out. Flame sensors can go bad and occasionally need to be replaced. Poor flame sensor positioning.
What causes a pilot to not sense flame?
Poor flame sensor positioning. The flame sensor might be fine, but isn’t positioned right and so cannot sense the pilot’s flame. Defective ignition board. The small computer control board that controls the gas flow, spark and the rest of the ignition sequence may be bad. Insufficient gas pressure.
How long does a furnace stay on?
Situation: You turn the thermostat up, the furnace ignites and the burner comes on. The furnace stays on for a while (maybe 1 minute, maybe 10 minutes) and then goes out. The fan continues to run even though the flames and pilot light go out.
How long do you have to hold the pilot button on a furnace?
Once you light the pilot, you need to keep the button depressed for at least 30 seconds (sometimes up to 1 minute).
Do direct ignition furnaces have pilot lights?
If you have a direct ignition furnace, you won’t have a pilot light. These furnaces skip steps 3-5 and instead light the burner directly. Your furnace will still have a flame sensor, but it will be over the burner’s flame. If you have a furnace with a standing pilot light, step 4 won’t happen.
Why won't my furnace stay lit?
A furnace that doesn’t stay lit can be caused by an overheating exchanger. That also means there’s limited air flow getting into the heat exchanger, which can be caused by these 3 issues:
Why does my furnace turn on and off?
If your furnace turns on several times and each time it goes off after a few seconds, you probably have a dirty flame sensor rod.
What to do if your thermostat is not working?
So, call an expert HVAC technician to check if your thermostat has issues and if it’s the one causing the furnace not to stay lit. The HVAC pro will advise if you need to replace the thermostat or a simple fixing or adjusting is required.
What is a furnace thermocouple?
A furnace thermocouple is a sensor that detects the functioning of the pilot light. If the pilot light goes off, the thermocouple shuts off the gas valve to preempt any accidents.
What happens if a furnace doesn't shut down?
The worst-case scenario is that the safety features could also be faulty, and if the overheating furnace doesn’t shut down, that could start a fire.
How long does a furnace last?
Furnaces are created to work in cycles that last 10-15 minutes under normal circumstances. Sometimes, however, your furnace runs for a few minutes then stops.
How old should a furnace be to replace it?
There’s no negotiating with an old dysfunctional furnace. You simply need to replace it. The U.S. Department of Energy advises that a furnace that’s 20 years or older should be replaced even if it works fine .
How to keep a furnace pilot light lit?
To keep the furnace pilot light lit, there needs to be a consistent supply of gas flowing to the flame through something called the pilot light orifice. If this tube is clogged or dirty, there won’t be enough gas flow to keep the flame strong. If the flame isn’t strong enough, the thermocouple won’t sense it and may shut off the supply ...
Why won't my pilot light stay lit?
However, if your thermocouple is damaged, dirty, or bent, it may inaccurately sense that your pilot light is off and turn off the flow of gas to your system . Without any gas supply , your pilot light won’t stay lit.
What happens if the pilot light is not strong enough?
If the flame isn’t strong enough, the thermocouple won’t sense it and may shut off the supply of gas to the flame. You may issue the pilot light orifice if you notice that your pilot light flame is a weak yellow color rather than blue.
What does it mean when a pilot light goes out?
If your gas valve is set to OFF or is faulty in some way, a consistent supply of gas won’t be delivered to your pilot light, resulting in a flame that goes out.
What is a bad thermocouple?
Bad Thermocouple. A furnace thermocouple is a safety feature that regulates gas flow to your system based on whether the pilot light is on. In simple terms, the thermocouple checks to see if your pilot light flame is lit and turns off the gas flow if it senses that your pilot light is off, so you don’t have gas building up in your home.
Explore Simple Solutions First
Let’s start first by assessing if you can quickly resolve your pilot light issue with basic troubleshooting.
Your Thermocouple Is Bad
Your thermocouple, also known as a “flame sensor,” is the copper tube that’s located next to your pilot light. A furnace’s thermocouple works to determine when to shut off the gas that flows into your system.
Your Pilot Light Orifice is Dirty
The gas powering your pilot light flows through a pilot light orifice. If this orifice becomes clogged with dirt, your flame may weaken to the point that your thermocouple can no longer sense it. When pilot lights begin burning a weak yellow color instead of a strong blue color, a dirty pilot light orifice is often to blame.
Your Gas Valve Needs Attention
The gas valve on your furnace delivers the gas your pilot light needs to remain lit. If the valve is turned ON, but your pilot light won’t stay lit, the problem might be a broken gas valve. The solution most likely will be to replace the valve.
Your Gas Regulator is Faulty
Your gas regulator works to decrease the pressure of the natural gas that’s provided to your home. You can typically find the regulator at your gas meter. If the regulator is old or faulty, the gas may not flow through it at a steady enough pressure to support your furnace’s pilot light.
Why is my furnace not turning on?
Another reason your thermostat may not be turning on your furnace is if someone has messed with your programmable thermostat. Although you have the heat setting on, your thermostat could just be following its directions to not turn on for another hour or two.
Why won't my furnace ignite?
If your problem is not with your gas line, see if your pilot light is lit, since your pilot light or ignition sensor is the most common culprit behind a furnace that won’t ignite. If this is your first time turning on your furnace this season, keep in mind that it may take a little extra time for the pilot light to turn on. One giveaway that your problem is with your pilot light is if you hear the furnace click on, but it doesn’t fire up. If your pilot light is the problem, take a look at your heater for directions on how to relight your pilot light, as this information is usually on the label.
What If My Furnace Is Not Igniting The Burners?
If you suspect that your furnace is not working because the burners aren’t igniting and want to try to troubleshoot the issue, check to make sure your gas line is turned on. You can usually see if things are working by turning on another gas appliance, such as your gas stove. If it appears that your gas is turned on, there could be a gas leak that is preventing your furnace from igniting your burners. If you smell gas near your unit, leave your home immediately and call your local utility provider.
Why is my central heating not working?
We already mentioned that your thermostat could be the reason your central heat is not working. While there are some serious thermostat problems that could be preventing your furnace from turning on, there are also some more basic reasons that your home might be cooler than you’d like. While it may sound silly, some homeowners realize that the issue is that they don’t have their thermostat set high enough. This could happen in homes where not everyone agrees on what temperature the thermostat should be set to. If your significant other is leaving the thermostat five degrees cooler than how you would like it, and you didn’t realize the setting had been changed, there’s a chance that your home has technically heated to its specified temperature, it’s just not the temperature that you had in mind.
What does it mean when your furnace smells gas?
If it appears that your gas is turned on, there could be a gas leak that is preventing your furnace from igniting your burners. If you smell gas near your unit, leave your home immediately and call your local utility provider.
How to tell if thermostat is working?
If you want to determine if it’s your thermostat that’s causing your heat to switch off, grab a thermometer and tape it to your wall. Make sure that you place a few layers of paper towels behind the thermometer so that any heat coming through the wall doesn’t affect its reading. After fifteen minutes, check the temperature on the thermostat. It shouldn’t deviate more than a degree or two from the temperature reading on your thermostat. If it does, you probably have a malfunctioning thermostat and you will need to have it calibrated.
How long does it take to check the temperature of a thermostat?
After fifteen minutes, check the temperature on the thermostat. It shouldn’t deviate more than a degree or two from the temperature reading on your thermostat. If it does, you probably have a malfunctioning thermostat and you will need to have it calibrated.
Why Is My Furnace Not Igniting?
If you have a furnace and it won't ignite, there could be any number of problems. Each furnace has its own internal components that will need to be inspected in order for this problem to be resolved.
Should I Replace My Furnace If My Ignitor Stops Working?
It is common for an ignitor to go bad in most furnace types. This can be very frustrating because this may require furnace repair technicians to come out and fix, which could cost you big bucks. It depends on the age of your furnace and how frequently you've had to make furnace repairs to determine whether a new furnace installation is in order.
Why is my gas furnace not turning off?
Gas Valve Problems. Your gas furnace has a gas valve that could affect the pilot light since it supplies the flame with gas. Check the gas valve to make sure it's not set to "off.". If it's on and there's still an issue, the gas valve could be faulty.
What happens when the pilot light is out on a furnace?
If the pilot light is out, there's no way for it to light the main burner, which means your house will get cold quickly.
Why is my pilot light not working?
The thermocouple is often the culprit if your pilot light doesn't stay lit. If the thermocouple gets dirty, it could block the sensor. You can clean your thermocouple using an emery cloth or steel wool on the sensor tip to get rid of corrosion. If it's clean but the pilot light continues going out, the thermocouple could be damaged or bent.
Where is the pilot light on a furnace?
The pilot light location can vary, but it's usually near the bottom of the furnace, often behind an access panel. Look for a gas valve and two copper tubes attached to the control valve to lead you to the pilot light. Refer to the owner's manual if you still have it or look for a label on the furnace with instructions on how to light it ...
How does a standing pilot light work?
How Standing Pilot Lights Work. Newer furnaces use electronic or hot-surface ignitors, but an older furnace might have a standing pilot light, which is a flame that burns continuously. The furnace supplies a constant, small amount of gas to the pilot light to keep it burning. It serves as the ignition source for the main burner.
