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:
- The wall switch is bad
- Your pilot flame is bad
- Your thermopile is bad
- 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 the fireplace’s function?
The way millivolt gas fireplaces work is that the pilot light heats up a sensor (commonly called a thermocouple or thermopile). This generates electricity when heat is applies to it (not much, actually under 1 volt). This small amount of voltage is sent to 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 loss of this 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.
Testing the Wall switch
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:
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
- 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. Here is a short video that shows how the flame is engulfing a thermopile sensor:
This is important because those sensors need to be a a high enough temperature to produce the correct amount of voltage. If the flame is yellow, tall, or not engulfing the thermopile and/or thermocouple:
this is not a good thing. Yellow flames seem to pull away from the sensors as the flame shoots straight up in the air. Sort of like this:
Notice how the flame is not wrapping around the sensor like the previous video. It is barely touching it.
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, your thermopile or thermocouple could be perfectly fine, but they will not have enough direct heat to send enough voltage to the main control valve.
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 can also order pilot assemblies online from sites such as Fire Parts.
You will need to know the make and 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.