What Should a Gas Grill Flame Look Like? [Explained With Pictures!]

Gas grills are a convenient way to sear steaks at high temperatures. But, many people don’t know what a gas grill flame should look like. This blog will give you some tips to help you figure out how well your gas grill flame is showing and what it might need to work better.

So, what should a gas grill flame look like? The flame color of both propane and natural gas grills should be blue to provide desired heat and maintain a specific temperature inside the grill. You will only observe a tiny yellow color at the tip or the core of a healthy flame of a gas grill. The blue flame also indicates that gas is undergoing complete combustion. Moreover, the blue color of propane gas is more visible compared to natural gas. You may assume natural gas flame is colorless in bright weather as the blue color of natural gas flame is less visible under the light. To verify the flame color of the gas grill, you should observe it in the dark. If you observe orange, green, or yellow tall gas flame, it may show that there is something wrong with your gas grill.

Natural Gas vs Propane Healthy Flame Nature

If every component of a gas grill is perfectly set, and you are not observing the blue flame color of the gas grill, there are chances that the gas is impure.

Both propane and natural gas are popular substances being used as an energy resource in gas grills as they quickly burn with a high temperature when they come in contact with a spark.

If we compare propane or natural gas flame nature, propane burns around 20 degrees Celsius hotter compared to natural gas if undergoes complete combustion. The complete combustion of gas produces carbon dioxide and water vapor. That said, the flame color of natural gas and propane is blue.

The temperature of a healthy blue flame of propane is around 1980 degrees Celsius, and for natural gas healthy blue flame, the temperature is around 1960 degrees Celsius.

The flame of natural gas or propane has three parts i.e. tip, core, and bottom as shown in the illustration below:

a gas flame regions

Due to the different chemical properties of propane and natural gas, the tip of a healthy propane flame is slightly yellow, the core is light blue and the bottom area of flame is dark blue.

For a healthy natural gas flame, the color is slightly yellowish-white at the core, while the remaining areas of a healthy natural gas flame are below. The side-by-side comparison of a flame of natural gas and propane is shown in the figure below.

side by side comparison of a healthy propane and natural gas flame

Reason of Yellow, Orange, or Red Flame Color in a Gas Grill

When a major portion of a gas flame is any color other than blue, it means that the gas has not undergone complete combustion.

For efficient combustion, the most important factor is the air-to-fuel ratio. If the fuel is not mixed with a sufficient volume of air, it will not undergo complete combustion.

Due to incomplete combustion, carbon soot is also formed along with other gases. The orange/yellow/red color observed in the flame of natural gas or propane is due to that carbon soot.

The temperature of that unhealthy flame of propane or natural gas is around 1000 degrees Celsius.

The soot deposits on the cooking grates and also in the burner. In extreme cases, it may even block the airflow to the burner, leading to flame out. Apart from showing yellow/orange flame color, that unhealthy flame can seem to be taller than a normal blue-colored flame. Yellow or orange flames due to incomplete combustion in gas grill, are 1 to 2 inches taller.

Sometimes, things get uncontrollable to alleviate the cause of the yellow or orange flame of a gas grill. This happens when there is windy weather, high humidity in the ambient air, and the presence of dust particles in the air. This is by nature. You can’t control this.

However, you can control the components of your gas grill if these are causing incomplete combustion of gas and resultantly, causing yellow or orange flame. This is what I’m going to cover in the next section.

Causes of Yellow or Orange Flame Color in a Gas Grill

If your gas grill gas orange/yellow flame, it means that there is crap (leftovers of food, grease, carbon soot, etc.) burning off the grill bottom or flavorizer bars, or your gas grill has incorrect air/gas mixture due to blockage.

Here are some obvious causes of incomplete combustion of a gas that leads to the yellow or orange flame of a gas grill:

  • Burner tube is either broken or has food particles and grease buildup in its holes
  • Air shutter is not properly adjusted
  • Grease is accumulated on the flavorizer bars
  • Cracks in the hose or manifold of gas grill
  • Gas grill orifice is blocked with carbon soot, grease and spider nest
  • Spiders have made their nest in burner and venturi tube
  • Pressure regulator is stuck/not working

Let’s discuss the causes of a yellow or orange flame on a gas grill in detail.

Pressure Regulator is Not Working

The primary cause of a low flame in a gas grill is that the pressure regulator of your gas grill is stuck or not working properly. This usually messes up when you quickly turn on the burner before the propane tank valve or shut the propane tank valve before turning off the burners.

A pressure regulator is a device, which is connected with the propane tank to regulate the pressure of propane throughout the connections in a gas grill for efficient combustion.

The reason for using a pressure regulator in the gas grill is that the propane tank valve should be fully opened. You shouldn’t control the gas pressure by messing up with the propane tank valve.

If the valve of the propane tank is partially opened, it can cause leakage of the propane out of the tank.

This is why the pressure regulator is connected through a hose with the propane tank to control the pressure.

In most of the propane gas grills, a 20LB propane tank is used, based on which a specific pressure regulator is designed to control and pressure.

This is the pressure regulator installed in Weber gas grills to connect with a 20lb propane tank. These pressure regulators are non-adjustable i.e. they are only designed to be used with a 20lb propane tank.

In this way, you really can’t control the flame height as the pressure regulators in gas grills are preset according to the design specifications, and you can’t adjust them.

But, the pressure regulator can be stuck or can stop working, if you mess up with the startup or shutdown procedure of your gas grill, or you use the wrong pressure regulator with the propane tank and vice versa.

So, you should first perform the following steps if you’re observing the yellow flame in your gas grill due to the insufficient gas flow. These steps are advised to follow if the pressure regulator of your gas is stuck that is causing low pressure.

  • Open the lid of the gas grill
  • Turn off the valve of the propane tank
  • Disconnect hose and pressure regulator from a propane tank
  • Turn the knob of the burners valve to full/high setting for up to 3 minutes to bleed out any crap in the gas line of the grill
  • Reconnect hose and pressure regulator
  • Slowly turn on the propane tank valve. Make sure that it should be fully opened.
  • Slowly turn on the burners’ valve and ignite the grill.
  • You should see a blue flame after these steps. If you don’t, you should buy a new hose and regulator for your gas grill. My choice is this one for a gas grill with a 20lb propane tank.

Air Shutter is Blocked or Not Adjusted

Just like a pressure regulator is designed to supply a specific amount of propane for combustion, the air shutter is a small tube ahead of the burner valve, having an opening along the circumference, to control the amount of air entering the venture tube leading to the burner.

The illustration of air-shutter and venturi tube assembly leading to the gas grill burner tube is shown below:

schematic of a air shutter assembly of a gas grill

There is a sleeve on the opening of the air shutter that can be adjusted through the screw to control the airflow. It is preset by the company based on the design specifications. For the natural gas grill, the opening will be different. For propane grills, the opening of the air shutter will be different. If you have previously messed with the opening of the air shutter, unscrew the plate and rotate it to offer more opening to ambient air.

Moreover, around the opening of the air shutter of a gas grill, there is a screen to filter dust particles in the air.

If the screen is clogged with dust particles or spider webs, it will not allow sufficient air to enter the venturi tube and mix it with the gas. Due to that reason, there will be incomplete combustion and yellow or orange flame on burner tubes will be observed.

You can clean it with a wire brush or toothbrush. You can check out this guide for more details.

Food Particles and Grease Buildup in Burner Tube Holes

Burner tubes are long metal pipes where gas enters for combustion. The flame spreads from one end of the tube to another through many holes drilled on its way, making it appear as a small orange tube. Natural gas grills’ burner tubes have small size holes compared to the propane gas grills’ burner tubes.

So, first, you have to make sure that if you have recently replaced the burner tubes for your natural gas grill, you have purchased the right one.

Another reason for yellow or uneven flame on your gas grill is due to clogged burner holes. When a gas grill is subjected to prolonged cooking hours at high temperatures, leftovers of food, grease, and carbon soot start depositing in the burner holes.

Even though a proper air/gas mixture is carried out in a venturi tube, the buildup in the burner will also burn with the gas resulting in the yellow flame.

Moreover, when air/gas mixture is forced to pass through a clogged burner, it loses the pressure required for efficient combustion. It also causes yellow/orange flame on a gas grill.

Make sure that burner tubes are not bent, or there is no dent on the burner tube of your gas grill.

To clean the burner tube, you should use a grill brush or a tip of a utility blade to clean out the clogged holes of burner tubes.

Furthermore, take a paper towel and wipe it under the burner tube to clean the grease buildup and debris. You can use this long nylon brush to clean the inside of burner tubes.

One person had thoroughly cleaned his gas grill burner tubes and was able to get the blue flame back on the gas grill as shown in the below picture.

blue-colored gas flame started showing after cleaning burner tubes

If there are stubborn grease stains and a rust layer has developed on the burner tubes, you should put them in the bucket of warm soapy water for some time and scrub it with the wire brush. After washing, dry the burner tubes thoroughly. If they are enameled burner tubes instead of stainless steel, you can season them with cooking oil. But, make sure that the burner holes are not blocked.

Gas Grill Burner Valve Orifice Is Blocked

The orifice of a gas grill is attached to the valve. The air shutter of a gas grill is attached to the orifice. So, if the orifice is not suitable for a gas grill or is blocked with anything, there will not be optimum gas flow, due to which you will observe yellow gas flame on your gas grill.

The picture of an orifice in a gas grill is shown in the figure below.

orifice of a gas grill

In the above picture, the orifice is in golden color. For the natural gas grill, the orifice size is larger than the orifice size of a propane grill. So, if you use a propane gas grill orifice in your natural gas grill, less amount of gas will flow out of the grill, resulting in incomplete combustion and yellow flame.

Moreover, due to combustion, carbon soot or rust can build up on the orifice hole if you do not clean your gas grill regularly. So, if you are observing a yellow flame on your gas grill, you should check out the orifice and clean it with a cloth.

Spider Nests in Venturi Tube of a Gas Grill

A Venturi tube in a gas grill is intended to mix air with the gas by creating a low-pressure region inside. Spiders can enter the venturi tube through burner tube holes. This can also limit the supply of air and gas mixture to the burners, and can yellow flame on your gas grill.

What About Green Flame of a Gas Grill?

The green grill flame of a gas grill is also a sign of an unhealthy flame. The green color is infused into the gas grill flame shows that copper is present in the flame. If any part of your gas grill is plated copper, it can cause a green flame.

Moreover, if you have used a copper brush instead of stainless steel brush to clean the grill, the copper could scrape off of the brush and mix with the air/gas mixture, resulting in the green flame.

Furthermore, the orifice in the gas grill burner valve is made of brass, and brass is a mixture of copper and zinc. So, there are the chances that there might be some copper present as an impurity in the orifice material that could mix with the gas and result in the green flame.

Can You See Propane and Natural Gas Flame?

The healthy blue flame of propane and natural gas can be properly visible in the dark. The blue color of a natural gas flame is a bit dimmer compared to that of a propane flame. But, you will still be able to see it in the dark.

Healthy propane or natural gas flame can be 1 to 1.5 inches taller on the highest setting. The unhealthy yellow-colored natural gas or propane flame can be up to 2 inches taller.