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Why Do I Need An Air Mixer For My Propane Fire Feature?

Fireplace Doors Online is here to explain the difference between the two gasses, and why it is so important for propane to be properly aerated!

 May 15, 2017    Outdoor Living, Fire Pits, Fire Bowls & Fixtures

"Why do I need an air mixer?" featuring the square Sierra fire pit table - 44 inchAre you thinking of installing an outdoor fire feature? Or perhaps you are planning on converting your existing wood-burning fire pit to a more fuel-efficient gas option? Either way, you'll have to decide exactly which type of fuel you want to burn: natural gas (NG) or liquid propane (LP). If you are a novice in this subject, you may not realize that there is a big difference between the two gasses. Liquid propane is heavier than natural gas. It also does not burn as clean. In fact, when it burns, it gives off a lot of smoke which results in soot buildup. In order for this gas to burn purely and efficiently, it needs to be combined with oxygen prior to combustion. In addition, it also needs adequate ventilation throughout the burn process for safety purposes.

So how does one safely use propane as a fuel source for an outdoor fire feature, such as the 44 inch Sierra square fire table (shown left)? It's quite simple! All it takes it the use of an air mixer. Fireplace Doors Online is here to explain why it is so important for propane to be properly aerated. We've also included an infographic for your convenience.

What is an air mixer?

Infographic for propane air mixer.An air mixer for propane usage is a combination of brass and/or stainless steel fittings that literally fit into the palm of your hand! (See? It's not as big and complicated as it sounds!) Essentially, it is an extra connection piece with two male ends that allows for gas and air intake. It easily attaches to the natural gas line on one side and a coupler extension with two female ends on the opposite end. The union of the air mixer and coupler disperse the gas through a nipple, which is hooked up to the burner of your fire feature.

Why do I need an air mixer for my propane fire feature?

Like we mentioned before, liquid propane is much heavier than natural gas, and also not as clean. In order to counteract these issues, an air mixer is necessary. When you turn on the gas flow with your valve key, pressure forces the fuel through the line toward the burner. As it approaches the air mixer, oxygen is sucked in through six external holes, effectively diluting the propane and converting it from liquid to aerosol form! It then ends its journey with the nipple connection, exiting the portholes in the burner as propane gas. 

Many of our products come with an air mixer. This enables customers who have access to both fuel sources to convert from natural gas to propane in the future. Or, for those who are converting from a wood fire pit to propane, our fire pit ring burner bundles conveniently include the air mixer so that you don't have to acquire it separately. 

In addition to utilizing this component in your propane feature, please make sure that you have adequate ventilation. This allows for better dispersion of gas and air circulation throughout the feature. If propane were to gain access to the bottom of a fire table or bowl through air pockets in your media, it could become trapped and potentially explode, resulting in damage and injury. Specialty ventilation collars or airflow gaps at the bottom of an urn or fire pit allow for oxygen to enter the decorative accent and further mix with the propane.

Where do I install the air mixer in my fire feature's gas line?

The air mixer component will be installed just before the burner, but let's start at the beginning to make things a little clearer.

  • Your gas line will feed right into your shut off valve ("T" shaped), which is covered by a safety flange on one end of the "T".
  • A valve key is inserted into the flange to turn the gas pressure on and off. On the other side of the "T", you'll connect your whistle free flex line.
  • Depending on the configuration of your fire feature in reference to the installation thus far, you may need an elbow connection (for example, if you are routing the gas upward through a pillar or stand to the fire feature) at the end of the flex line.
  • The air mixer is affixed to the elbow in this case, followed by the coupler.
  • The nipple is tightly screwed into the coupler and connects with your burner on the other end.

While this sounds quite simple, if you are unsure of the process, please contact a certified gas professional to oversee this project for you. Safety should always be a top priority for you and your loved ones. Please vent responsibly when it comes to burning propane!



Last updated on September 21st 2020.


I keep getting propane back flow coming out from the air mixer holes unless I have the regulator at very high, flames are too big! Any lower and back flow occurs. Where did I go wrong?

We would need to see your setup or what parts you have installed before we can advise.
the flames on my lp fire feature are not stable.
they continue to get larger and I have to keep adjusting the regulator. Any ideas on why this is happening.

FDO Staff:
Did you check your propane tank pressure? It could be the pressure regulator as well. Have a gas certified person come and check out your setup.
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