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Why Is My Propane Air Mixer Leaking?

A propane air mixer will leak if there’s reverse pressure – gas being forced backward from the fire pit burner toward the tank.  The good news is that an air mixer is a fairly simple product and easy to troubleshoot.  

There are several reasons why gas leaks from an air mixer.  In this article, we’ll talk about how to test for those problems and how to solve them.

How to Test a Propane Air Mixer

The first step in troubleshooting your air mixer is the simple “one-handed eyeball test.”  

Donnie, a member of the Celestial Glass Technical Team, demonstrates how to perform this test in the following video. To skip to the test, fast forward the video to approximately 5:40 point.

This quick test will let you know which direction to head in tracking down your problem.

A Missing Coupler/Sleeve on Air Mixer

The propane air mixers we sell for our DIY kits come with three pieces—the air mixer, a coupler, and a male fitting that attaches to the burner. Some burners already have the male fitting, so you would need to remove the one that comes with the air mixer to attach the coupler to the burner. 

So one problem we often see is that the coupler is accidentally removed along with the male fitting. The male fitting may be made from the same material as the coupler, and if you don’t realize they are actually two different pieces, you might unscrew the coupler (and the male piece), thinking that you’re just removing one. 

When this happens, the air intake portion (the segment with small holes) is too close to the burner pan. There isn’t enough space for the gas to mix with the air before reaching the burner. This causes turbulence and backward pressure releasing gas out through the intake holes.

propane air mixer coupler

Burner Covered with Sand

Another cause of backward pressure on the propane air mixer is sand. You never want to cover a propane burner in your fire pit with sand because it restricts the gas flow, causing the excess gas to “beat a retreat.”  Sand creates a nice look, but it can only be used with natural gas burners.  

Natural gas doesn’t require an air mixer, and the gas supply line can provide sufficient pressure in this type of installation to force its way outward.  

If you covered your propane burner with sand, you’d need to remove it. Instead, use a filler material such as fire glass or lava rocks to cover your burner.

Spiders or Other Debris

Obstructions are another cause of reverse pressure. Spiders love to make their home inside of propane air mixers.  They crawl up inside those air holes and are protected from predators. It’s a safe, ready-made home.  The only reliable way to check for spiders is to disconnect your air mixer from your fire pit and visually inspect it.  

Additionally, you want to ensure the fire pit burner is clear of debris.  To check the burner, remove your fire glass or lava rocks from the top of the burner. Then light your fire pit.  You should see a flame coming from each hole.  If there are holes with no flame, you’ll want to inspect it further to see if some debris inside the burner is blocking the gas flow.

Cap or Feeder Pipe Is Screwed in too Far

Another common problem involves the reversible burner ring. If you have a reversible burner ring with a threaded cap, the cap or the threaded input pipe may be threaded in too far. 

Round burner rings have a set of four holes in the fitting that comes up through the center section of the ring.  These four holes feed gas to the rings of the burner.  

If the top cap or threaded input pipe is screwed in too far, they can obstruct the holes in this center fitting and block the flow of gas to the burner rings. So, while you want to have your fittings screwed in tightly, you may block your fuel source if you overdo it.

burner rings cap threads

Wrong Direction

Though not common, sometimes people fail to see the arrows engraved on the propane gas air mixer and install it in the wrong direction. If you spin the mixer around, you will find the arrows. The air mixer should be installed with the arrows pointing toward the burner.

Incorrect Installation

There’s one more possibility to consider if all else has failed to fix the problem, check the order of equipment feeding gas to your fire pit. Leading from your propane tank should be the regulator, then the key valve (if your set-up has one), and finally the air mixer, which attaches to the burner. Occasionally, we find these have been installed in the wrong order causing a variety of problems.

Still Leaking?

If all this troubleshooting still leaves you with a problem, please contact us. We’re happy to answer all your questions.

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