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The Main Burner Flame Will Not Come On or Stay On

Gas Fireplace Repair – My Main Burner Flame Will Not Turn On

 

This section will help you diagnose and fix simple issues related to your main burner flame. If you do not see a pilot light in your fireplace please refer to the Pilot Light Troubleshooting page.  Also, if your main burner will run for a while, then go out, make sure your pilot stays lit.  If your pilot goes out as well you can refer to the Pilot Light Issues tutorial.

Main burner issues can only be four things:

  1. The wall switch is bad
  2. Your thermopile is bad
  3. Your pilot flame is bad
  4. Your main control valve is bad

Again, thankfully, all of these issues can be easily tested, and most of them can be fixed very easily.

 

Wall switch issues

The most simple of these issues, and consequently the most common, is a bad wall switch.  Every year I always get tons of service calls that are the result of a bad wall switch. Again, this is probably the easiest thing to test and replace.

How does the wall switch affect ta fireplace’s function?   The way milivolt gas fireplaces work is that the pilot light generates electricity (under 1 volt) and sends it the wall switch.  When you flip the switch on, it will send that voltage back to the fireplace and signal to the fireplace to turn on the flame.

What can happen over the years, is that the connections inside the switch can get dirty, corroded, or broken, causing a large drop in voltage at the switch.  So by the time the small amount of voltage gets sent back to the fireplace, it is not enough to signal the fireplace to turn on.

To test this, you will only need a screwdriver.  First you will want to find the wall switch that turns on the fireplace.  Again, this switch has less than 1 volt of electricity running through it, so there should be no issues with accidentally shocking yourself.  However, you will want to make sure that you have located the switch that turns on your flame, NOT your FAN or NOT for anything else such as a LIGHT SWITCH.   (You can always verify this after we take off the cover plate as just looking at the wiring should tell you what is what, but more on that later)

Next, we want to take our screwdriver and remove the cover plate:

 

Gas Fireplace Repair Wall Switch

You should just need to remove the two screws on the face plate with a flat head screwdriver.   Next, we should double check the wiring to make sure we have the right wall switch.  We should just see two thin wires attached to the switch (pictures to follow).  If it is a high voltage switch, we would see a third wire attached to the Terminal screw (as shown above).  If you are unsure, you can always turn off the circuit breaker for the room and make sure the power is turned off.

Next, we want to unscrew the next two screws that hold the switch itself onto the receptacle box.  Once they have been unscrewed enough you should be able to pull the switch right out of the box.  You want to be able to pull it out enough so that you can access the two wires on the side of the switch.

Now you’ll want to unscrew the screws that the wires are attached to.  Again, you only need to unscrew them enough to be able to pull the wires off.  Once you have the wires removed from the wall switch itself, all we are going to do is touch them together.  This is basically just bypassing the wall switch and if the fireplace comes on, this should tell us right away that the old wall switch is bad.  If it is bad you should replace it with any wall switch you want (you can pick these up at any home improvement or hardware store).  You’ll probably want to bring it with so that you can stick with the same color and that it will match with the rest of the house.

How to test of your pilot flame is bad

This is probably the easiest of the tests, and it doesn’t require any equipment.  You just need to visually inspect your pilot light.  It should be blue, without much yellow in it at all.


Time to Complete:  >5 minutes

Recommended Tools

  • Your Eyes

 

A healthy pilot flame should look like this:

It should be blue, and the flame should engulf the sensors and almost wrap around them.  This is important because those sensors need to be a certain temperature.  If the flame is yellow:

this is not a good thing.  Yellow flames seem to pull away from the sensors as the flame shoots straight up in the air.

The easiest way to describe it:

A healthy pilot flame will be much like a blue  “blow torch” flame. It will shoot sideways and be directly on your thermocouple and thermopile sensors. An unhealthy yellow flame is more like a “candle”. It will shoot straight up in the air and may not engulf your sensors.

If the flame is not healthy, it will not engulf the thermocouple or thermopile and the result: your thermopile is not hot enough to create the voltage it needs to ignite the burner.

If you determine that you have a bad pilot flame, you can either clean out your pilot hood and orifice with a wire brush (cheap but not long term) or replace the pilot orifice and hood (this is called the pilot assembly)  Replacing the pilot assembly takes a little more time but will last ten times longer.

You can purchase a pilot assembly specific to your fireplace at your local dealer.  You will need to know the make an model of your fireplace.  Click here if you are having trouble finding it.  Once you find the make and model of your fireplace, you can visit the manufacturers website.  Most of them have a “dealer locator” section where you can find a dealer in your area to purchase one from.


 

70 comments on “The Main Burner Flame Will Not Come On or Stay On

  1. i chand thermopile wall swich mainbur flame not come on

    • How is your pilot flame? Does it engulf the thermopile completely? If your pilot flame looks very yellow (instead of blue) or it is not wrapping around your thermopile sensor you may need to replace the entire assembly.

  2. Davie morris on said:

    No gas comes out of control valve…I do not have a basement; what could the problem be?

    • Make sure there is gas going IN to the control valve. Find any “shut-off” valves on the gas line going to the fireplace and make sure they are turned on (parallel with the gas line). They are usually located in your basement but if you do not have a basement, check your furnace room. If the fireplace runs on propane, make sure your tank is not turned off or empty.

  3. So every winter it seems like something goes wrong with our gas fireplace. Money is super tight right now so I decided to goggle how to fix it myself and found this page. Turns out it was the wall switch. Took me 5 minutes to fix. Thank you for this page.

  4. I can lit the pilot, the pilot light is on, when I turn it to on position. The pilot light is off right away. What is wrong with it? I need help to fix my fireplace, thanks. Ming.

    • This sounds like you have a honeywell valve that commonly had this problem. Try turning the knob to the “on” position VERY SLOWLY. Many times this will keep the pilot going. A permanent fix would be to replace the valve. However, if it is the valve I’m thinking of it has been discontinued and can be hard to find.

  5. Christine on said:

    To the techs of mygasfireplacerepair, Thank you
    so much for your troubleshooting advise. I followed
    the steps above for switch issues and found out the switch
    was bad which was causing the main unit not to light.As a homemaker I was determined to fix this myself and with your expert advise I did it. Thank you very much.

  6. I can see my pilot light so im guessing it’s my wall switch that needs to be checked out. The wallswitch is actually a thermostat though, can i still remove the panel?

    • Yes. Fireplace thermostats work the same way as wall switches, except they turn on and off with the temperature instead of by someone flipping them on or off. You can pull the front off the thermostat to find where the wires are hooked up. Take the wires off the terminals and connect them together just like bypassing the wall switch in the tutorial.

  7. I have a healthy blue pilot light, but the switch does not start the burner. I tested my switch and it seems to be fine and didn’t start the flame when I connected the wires. What is my next step?

    • Make sure your valve is in the “on” position and not the “pilot” position. Then, test the voltage on your thermopile (you can find the tutorial for this on this site as well). If your Thermopile voltage looks ok: we can jump the valve directly. Find where your wall switch hooks on to the valve. There are usually 3 terminals on the valve and the wall switch will connect to the outer terminals (these say “TH” next to them). If you connect a wire from the top to the bottom terminals (completing the connected between the TH terminals) it should come on.

  8. My gas fireplace is 2 years old. The pilot light is on and blue but the main burner will not come on at all. I took the switch apart and checked the switch twice and it is definitely not that. I also checked the voltage on the thermopile like you mentioned. It was at 840mV and did not budge when I flipped the switch. So I am out of options. Any idea what is wrong??

    • Make sure your valve is in the “on” position and not the “pilot” position. We can also jump the valve directly in case the issue is in the wiring. Find where your wall switch hooks on to the valve. There are usually 3 terminals on the valve and the wall switch will connect to the outer 2 terminals (these say “TH” next to them). If you connect a single wire to these terminals (completing the connection between the TH terminals) it should come on. If it doesn’t you should at least see a change in voltage. It it drops to 0, there is a short in your thermopile. If it still doesn’t drop at all, it could be your valve.

  9. Ann Mecanko on said:

    Same problem I have been seeing here. Pilot on and nothing else. Our switch is part of the main frame of the fireplace. We have someone coming out as we (seniors) are not able to accomplish your suggestions. I’m sure the fireplace needs a cleaning but we don’t actually use it much. My problem is the charges seem so expensive. I sure don’t want something replaced if it is not necessary. This sight has been so very helpful. And I am sure so many people are using your suggestions. I thank you in adance for any advice.
    Thanks

  10. Propane gas fireplace insert lights & stays on maybe 10-15 minutes & then turns itself off. Turned back on flame shoots very high, after few minutes, turns itself off again.
    Gas company people checked it twice, cleaned burners & can’t find anything wrong! But, problem still exists…
    Help!

  11. Cory on said:

    My pilot light is on, and is blue and moving a little like it should. It will not light though. I have removed the wall switch and touched the 2 wires together. Still doesnt light. The valve is turned on. What do I try next

    • admin on said:

      Use a digital multimeter and test the voltage on your thermopile sensor. Click on “Part II: How to test your
      Thermopile sensor” on the bottom of the post.

  12. Dan LaJoie on said:

    According to the gas company I have a main control value that seems to be leaking gas out of the value that is used to light the pilot and turn on the gas. He said there is a spring loaded value that should prevent the gas from leaking out of the valve stem. Although difficult, he said this could be removed cleaned and repaired, rather than replaced. This is a older majestic unit GS28A made in the 1970′s and a replacement control valve is not available. Is there anyway to get ahold of a parts diagram for the control valve?

  13. Jake Gilmer on said:

    Hello, I have a Superior brand electric fireplace. Pilot will light and stay lit but main burner won’t always come on when I flip the wall switch. I tried removing the switch and touching the two wires together and nothing still. Replaced switch anyway and still nothing. Replaced thermopile and put things back together and it lit right away. Three days later I tried it again and nothing? You can hear that the gas valve is not opening when the switch is flipped. I have a nice blue pilot but it is not “engulfing” the thermopile completely. It is touching one side of it only. I heated up the thermopile with a lighter when the switch wouldn’t work and tried it again and it immediately came on. I also tried jumping the two “th” terminals together with a jumper wire and it immediately came on also. Could this be an issue with the pilot assembly? Seems like the main valve is ok but maybe the pilot isn’t heating the thermopile enough? Any help is appreciated. Thanks in advance!

    • It sounds like its something in the wiring between the wall switch and the valve (especially if you get get it to come on by jumping the valve directly). Check to make sure your wall switch wires are securely on the terminals and that any connectors on those wires are still good. Otherwise the next step would be to get a Digital Multimeter and start testing your thermopile voltage.

      • Jake Gilmer on said:

        Thanks so much for the advice. I will check the wiring/connectors tomorrow morning and let you know what I find out. I do have a multi-meter and attempted to check the voltage of the thermopile but wasn’t really sure which setting to have it on as it is different from the one that you show in the tutorials. I don’t have much experience using one so I will probably have a couple questions re: that if the wiring doesn’t solve my problem. Thanks for what you do for us on this site. It is much appreciated!

  14. Jake Gilmer on said:

    I still haven’t diagnosed the problem with the main burner inconsistency. I had a question for you though. Sometimes when I flip the switch it comes right on. Other times, I don’t hear the gas valve open and nothing happens. A few times when the main burner failed to come on after flipping the switch I tried some tests. A couple times, I heated the thermopile with a log lighter and it opened right up and the burner came right on. Other times, I jumped the th terminals directly taking the switch out of the equation and I had the same response where the burner opened immediately and came right on. My question is how do I know if this is a switch wire issue or an issue with the thermopile not getting hot enough to generate the 1/2 volt or so required to open the gas valve? It is a brand new thermopile so I don’t think that is the issue. I need to get this fixed as I am selling the house and want to figure this problem out before the home inspection next week. Thanks again in advance

    • The only way to know for sure is to test the voltage on the TP terminals to make sure you are getting enough voltage out of the thermopile. Also, if the voltage changes after hitting the switch (or doesn’t change) that can tell you a lot about whats going on as well.

      You could check the wall switch connections on to the valve. Sometimes the connectors are bad or loose, or its possible the wall switch wire runs to a little toggle switch underneath the fireplace before hooking on to the valve; you could wire the wall switch wire directly to the valve.

      • Jake Gilmer on said:

        Thanks for the ideas. The way that my switch is wired makes it really difficult to run a new wire as it is routed out the opposite side as to which the switch is located. Also, I noticed that the wiring is similar to the wire on the thermopile in that it seems to have a sheath to protect it from the heat. I am not sure where to even get this type of wire? I could run a couple temporary wires to a switch right off the gas valve and out the front of the fireplace to at least do a test to rule out this problem though? Also, If you could run down how to test the tp terminals correctly. If you could advise me which setting to use on the multimeter to test and what values I am looking for that would be a huge help! Thanks in advance for what you do here! Cheers

        • You want to find the DC voltage part of the meter and put it on the lowest setting (this will detect electricity under 1 volt). Then go to the “How to test your Thermopile Section” to troubleshoot.

  15. Kate Balderson on said:

    I have a gas fireplace. However, I can get the pilot light lite and put it in the on position and it stays lite but the burners will not ignite. The flame is blue/yellow and I have not seen a switch, there is just a valve that is hooked to the gas line on the back of the unit. A friend of mine took it apart to check everything and clean what he could and the burners will still not ignite. I’m in desperate need of advice because its getting cold and this is what heats my house.

  16. I have a gas fireplace whose pilot is controlled by a wall switch. Neither the pilot nor flame come on. I did a continuity test on the switch and when it turned on, there was continuity. I didn’t try connecting the wires to see if that would start the fireplace. If the switch has continuity, do I need to put the wires together to bypass the switch, or should I go on and trouble shoot the rest? At this point, gas gets to the fireplace, but doesn’t come out to the logs. What should I check?

    • it sounds like you have an electronic ignition system, you’ll need to make sure you have power to the fireplace. Watch this video to see if you have an electronic system.

  17. thank you! just taking the wall plate off the switch and checking that the wires were tight saved me $$! just loose…tightened up and presto!
    electricity + gas = scary. I was worried to try the first thing to troubleshoot. Thanks for this info!
    Other good stuff on this site too! a thermo-what?!
    I’ll visit here with any more ?’s.
    Thanks again!

  18. Les Kuzdas on said:

    I have a Mendota fireplace model DXV-111-36N I replaced the thermopile and I still can not get the burner to come on. The pilot comes on and is blue and around the thermopile. This unit runs by remote, I disconnected the remote and jumped the main valve and it blows the pilot out. It’s an older unit, could the main valve went bad?

  19. Les Kuzdas on said:

    No clicking be the valve either

    • If your voltage is 0, that means there is a short in your thermopile. When your thermopile heats up, it should always create a minimum of 300 millivolts or higher. Try testing the voltage with it disconnected on the valve to be sure.

  20. Les Kuzdas on said:

    Not hooked up I get .3 Maybe my meter is screwed up?

    • Sounds like you don’t have your meter in the lowest setting. This looks like 300 something millivolts. If it drops to zero when you turn the fireplace on, you have a short in your thermopile

  21. Just moved into a house and it has a Heat N glo Sl-750TR. I vacuumed all the dust out. I then got the pilot light lit and it is nice and blue. The only problem I have is the flames once it is turned on seem low. I then turned it off and let it cool and removed the plate with all the holes and blew the soot out with air. Flames still low. I looked and it doesn’t have an adjustable knob for the flame. Is there anything I can do?

    Thank you

    • The Slimline series (SL-750TR, SL-550TR) are lower BTU fireplaces. They are not designed to have a large flame.

      Many times, it will take the fireplace around an hour before the flame will turn more yellow and look its best.

      If you think that there still is an issue with the flame height, its possible you might have some blockage in the burner tube. There is a certain spider that likes the smell of the natural gas additive (that sulfur gas smell) and will often build a nest in the main burner tube.

      To clear the blockage you usually have to remove the logs and burner to find the burner orifice (it is usually brass in color and looks like a bullet). Take a piece of wire and run it through the orifice and down the tube to clear out any blockage. If it is down far enough you may have to remove it from the valve itself.

  22. Doug Jackson on said:

    I have a natural gas ventless fireplace with a pilot light. The fireplace will light when the wall switch is turned on, and the burners will stay lit for anywhere from 30mins to a few hours. Then they will go out. The burners will come back on just by flipping the switch off then back on. Any advice?

  23. Linda Swenberg on said:

    Majestic fireplace. We do turn off the pilot every summer because it generates too much heat for summers in CA. This year I have a problem. My pilot is nice and blue and hitting thermopile. Thermopile generates 460 mV. Main burner lights but is very low blue flame. It extinguishes within minutes and so does the pilot. I called a local majestic dealer but they are not on NFI list. I told them I think I might have a vent blockage and I’d like them to check the vent. The tech did no cleaning or service and nothing with the vent but pulled the flex line off the valve and said the supply flow is low based on how it sounded (no manometer). Spent 5 minutes and charged me for 30. Told me to call plumber. I did and manometer is within range for fireplace specs. Called dealer back and yelled at them a bit. Owner came this time. “Knows this fireplace like the back of his hand” yet put logs back wrong when he left for day. Told me pressure could be good in supply gas but flow could still be low. How can that be if gas is compressible? No luck with this. What could be wrong and who do I call for help? Pilot looks good but when burner is on (briefly), the flame appears to draw away from thermopile.

    • Try running the unit with the bottom of the glass frame cracked open. If it stays running, you can determine if its a venting issue.

      A lot of these majestic fireplaces had collars up on top that would break loose and cause a leak in the firebox. Symptoms include the flame turning really blue and “ghosting” off the burner (burning up in the air) right before it went out.

      Take the glass off and shine a flashlight up into the top of the firebox. Then look into the upper louver area from the outside. If you can see light shining through you know the collar has a leak. If it does, buy some high temp silicone and seal it up.

  24. cc ayer on said:

    Thanks for the guidance. Don’t forget to check the connections under the firebox. After checking my wall switch, I reseated the flat clips and adjusted the wire down there and my flame popped on!

  25. Do I need a gas fitter to replace the pilot assembly? Or, is this a DIY job?
    Thanks for all the great info on this site!

  26. Our fireplace wouldn’t light for over a year. I just used this page, walked over snd flipped on the switch I never could figure out what it was for. Lol, the flame came right on.

  27. Kyle Westra on said:

    We have a superior gas fireplace. Pilot works fine. The switch works fine. The flames are only about two inches high. They used to work much better. Our furnace guy took the whole thing apart, cleaned out everything, and put it all back together. He also tested the gas line which checks out good. Still the same on the flame. Is this a valve issue?

    • Double check to make sure there is nothing the in burner tube connected to the valve. I’ve been on some service calls where the previous service tech did not go far enough down the burner tube to clear the obstruction.

      To test the valve, make sure to test the incoming pressure (“in” screw on the valve) and outgoing pressure (“out” screw -which is right next to the “in” screw). To do this you will need a manometer (a device used to test gas pressure). On the rating place for the fireplace it should tell you what the inlet minimum and outlet minimum is supposed to be.

      • Kyle Westra on said:

        Retested the tube, completely clear. My HVAC guy took apart the lines and checked the pressure like you suggested. In was good, out was bad. That is when he determined something was wrong with the valve. He said the valve needs to be replaced. My question is – where do I get a replacement valve? I’ve looked all over and can’t seem to find a supplier for this valve.

        • Certain valves (ei Honeywell) are no longer made and can be almost impossible to find. Check with the local dealer that carries your fireplace brand. Many times, there is a conversion or a compatible valve that can be used instead.

  28. brandon on said:

    We just turned on the pilot light, and it worked. then we switched the valve to “on” and the fireplace started up without us turning the wall switch on. The wall switch wont control the fireplace, how do we fix it

    • There must be some other switch turning the control valve on. Is there anything else connected to the terminals (maybe on the back side of the terminals). Sometimes there is a toggle switch underneath the fireplace near the control valve that will also turn on and off the fireplace.

  29. My wife and I are in a process of preparing to sell our rental property. One of the best features of the property is the gas fireplace in the recroom. We discovered that it is not working (pilot on but burner will not light up).

    So my wife set an appointment with a repairman who came to inspect the fireplace, and promptly declared that we would have to replace the whole fireplace as it was fairly old and not worth it to repair.

    I did some research and found this website. So I followed the instructions, checked the switch, pilot light and thermocouple/pile. I cleaned and vacuumed the dust as well as cleaned the glass while it was open, and lo and behold, my fireplace works as good as it ever did!

    I have no idea how much money I saved, but I am sure it is a lot. Although I was taking my time, I spent no more than 30 minutes from start to finish, including vacuuming and carefully cleaning the glass.

    Thank you very much!

  30. Thanks for the helpful info ,very easy to follow trouble shooting guidelines, turns the problem was the wall switch. Thanks again . P.S. Best of all the repair was free.

  31. Pilot wouldn’t stay on so I replaced thermo couple. It still couldn’t get it to work so I cleaned the pilot assembly with a bruch and with the glass front off the pilot will turn on. Once I clamp the glass front back on the pilot goes out. Any ideas on this one?
    Thanks for any help.

    • It sounds like its starving for air. Check for blockage in the flue (birds nests or bees nests are common) or a leak in the firebox. Shine a flashlight inside the firebox and see if you can see light shining through anywhere its not supposed to.

  32. Larry Mintun on said:

    I just want to be among the many to thank you for your advice. Sure enough, the switch was at fault. I really appreciate the straight forward high quality help you have provided. Thanks again.

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