A yellow flame on a decorative gas fire pit is usually normal — these burners are engineered to produce yellow light, not blue heat. What signals a real fault is soot, a flame that has dropped well below its usual height, or a flame that covers only part of the burner. Media depth, gas pressure and orifice sizing explain almost all of it.
This guide is for the fire pit that lights and then misbehaves. If yours will not light at all, or lights and dies in seconds, start with Why Won't My Gas Fire Pit Light? 9 Causes — that one covers ignition and gas supply from a dead start. Come back here once the flame itself is the problem.
What's in this guide
- Is a yellow flame actually a problem?
- Flame color and behavior, decoded
- Flame low across the whole burner
- Flame strong on one side only
- Flame that surges up and down
- Flame that is huge and roaring
- How deep the media should sit
- Black soot on the glass and table
- Wind blowing the flame out
- Who fixes what: you or a technician
Is a yellow flame on a gas fire pit actually a problem?
Usually not, and this is where most online advice gets it backwards.
A kitchen range premixes air with the gas before it reaches the flame. That primary air is what gives you a tight blue cone. A decorative fire pit burner does the opposite on purpose: it releases gas with little or no primary air, so the carbon glows as it burns. That incandescent carbon is the yellow, and it is why the flame reads as a wood fire instead of a blowtorch — the entire point of the product. See Gas vs Wood Burning Fire Pits for the comparison.
So judge the flame by three things instead of color: does it deposit soot, is it the height it has always been, and does it cover the whole burner? Flame shape also varies by burner design — see Fire Pit Burner Types.
What does each flame color and behavior mean?
Use this before you touch anything. The third column is the one nobody else prints: whether you are looking at a design characteristic or an actual fault.
| What you see | What it means | Normal or fault? | What to do |
|---|---|---|---|
| Tall yellow / orange flame, clean burn | Low primary air by design; glowing carbon | Normal | Nothing. This is the intended look. |
| Blue flame with yellow tips | Typical natural gas burn; some primary air present | Normal | Nothing. |
| Mostly blue, short, hissing | Too much primary air, or an air mixer set wide open | Fault (cosmetic) | Technician adjusts the mixer. |
| Yellow flame that lays down soot within an hour | Incomplete combustion — starved of oxygen | Fault | Reduce media depth first; then have the mixer and pressure checked. |
| Flame low everywhere, evenly | Insufficient supply pressure or volume | Fault | Check tank level; then line sizing and regulator. |
| Flame on part of the burner only | Blocked ports, buried ports, out-of-level pan, or water | Fault | Rake back media, clear ports, check level and drain. |
| Flame pulsing or surging on its own | Wind, or a partially tripped excess flow valve | Depends | Wind is normal; surging on a still night is a fault. |
| Flame lifting off the ports, roaring | Overfiring — commonly a natural gas orifice on propane | Fault — unsafe | Shut off gas. Licensed technician only. |
| Light soot on glass after a full season on propane | Propane carbon content | Normal | Clean the media; no repair needed. |
| Flame lazy and smoky, smells strongly | Severely incomplete combustion | Fault | Shut it down and call a technician. |
Flame height also tracks rated input — check How Many BTUs Does a Fire Pit Need? before concluding yours underperforms.
Why is my fire pit flame low across the whole burner?
Low and even all the way around points at supply, not at the burner. Gas appliances are designed around roughly 7 inches of water column for natural gas and 11 inches for propane, give or take an inch. Below that, the flame cannot reach height.
Run this test first. Light the fire pit, let it settle, then have someone start the furnace, tankless water heater or clothes dryer. If the flame visibly drops, the branch feeding it is undersized or the meter is at its limit — not a burner problem at all. Our fire pit gas line sizing guide covers pipe diameter, run length and total connected load, which is where this usually resolves.
On propane, check tank level first, then temperature: a small cylinder on a cold night struggles to vaporize fast enough for a high-output burner. Natural gas vs propane covers that trade-off.
Why is my flame strong on one side and weak on the other?
Uneven flame is almost always mechanical, and most of it is yours to fix.
- Blocked ports. Media dust, spider webs and insect nests plug individual ports. A soft brass brush and a thin wire clear them. Never enlarge a port.
- Media pushed around. Fire glass migrates when people rake it. Level it and re-check.
- Burner not level. Lay a 2 ft level across the pan both ways. Gas pools at the low end; so does the flame.
- Water in the pan. Rain that cannot drain sits on the burner and kills flame in that zone. Confirm the weep or drain hole is open.
Water is the one that returns every spring. A fitted cover from our covers plus the drain checks in How to Winterize a Gas Fire Pit prevent most of it. Corroded pans and burner hardware are in components.
Not sure whether you're looking at a fault or a feature?
Send a short video of the flame with the model and fuel type. We will tell you whether it needs a technician or twenty minutes with a brush.
Ask our fire feature team Find your manualWhy does my fire pit flame surge up and down on its own?
On a breezy evening that is wind, and it is normal. On a still night it is not.
The usual cause on propane is the excess flow valve inside the tank's service valve. It is a safety device: sensing a sudden rush of gas, it partially closes and limits flow to a trickle. Opening the tank valve fast while the appliance valve is already open is what trips it. The fix is free. Close the fire pit's control valve, close the tank valve, wait about a minute, then open the tank valve slowly, a quarter turn at a time, before opening the appliance valve.
If that does not restore full flame, suspect the regulator — not a homeowner item. Same for a control valve that no longer holds a setting; key valves are replaced by a technician, not adjusted by hand.
Why is my flame huge, roaring and lifting off the burner?
Stop. Shut off the gas at the valve and leave it off.
A flame dramatically larger than it has ever been, especially one that lifts off the ports and roars, means the appliance is overfiring. The classic cause is a natural gas orifice feeding propane. Propane carries roughly 2,500 BTU per cubic foot against natural gas at about 1,000, and runs at a higher supply pressure, so the larger natural gas orifice passes far more energy than the appliance was certified for. It happens after a botched fuel conversion, after a burner is reassembled without its orifice, or when a regulator is bypassed.
This is a fire and carbon monoxide hazard, and it is a licensed technician's job under the National Fuel Gas Code (ANSI Z223.1 / NFPA 54).
The expensive mistake: converting fuel yourself. A fire pit built for natural gas is not made propane-ready by swapping the hose. It needs the correct orifice, the correct regulator and, on many burners, an air mixer. Doing it by feel voids the manufacturer warranty, is a code violation under ANSI Z223.1 / NFPA 54, and can put a 65,000 BTU/hr burner well past its rated input. If you ever smell gas: do not touch switches, shut off the supply if you can do it safely, move away from the appliance, and call your gas supplier or the fire department from outside.
How deep should fire glass or lava rock sit over the burner?
Media depth causes more flame complaints than anything else, and it is the easiest to fix: you rake some out. The rule is hide the burner, do not bury it. Propane is heavier than air and gets trapped under a thick layer, starving the flame of oxygen and producing soot. On natural gas, excess glass mostly produces an uneven flame pattern.
| Source | Published guidance | Practical maximum |
|---|---|---|
| American Fyre Designs | 1–2" of media above the burner | 2" |
| The Outdoor Plus | No more than 1" above the burner | 1" |
| Celestial Fire Glass | Cover the burner by about 1/2", just until it disappears | ~1/2" |
| Solus Decor (linear burners) | Lava rock built up to the underside of the burner; no inch figure published | Not published |
Always follow your own model's manual over any general figure. If you cannot find it, our manuals and guides page is the fastest route to the document.
Media choice matters as much as depth: lava rock traps moisture and can pop. Fire Glass vs Lava Rock compares the two, and replacement media is in fire glass.
Why is there black soot on my fire glass and the edge of my table?
Some soot on propane is normal. Propane needs more than twice the oxygen natural gas does for complete combustion, and ambient air around an open burner does not always supply it. A light film on the top layer of glass after a season is a cleaning job, not a repair.
It becomes a fault when soot appears within an hour of lighting, black flakes drift off the fire, a greasy film builds on the table surface, or nearby siding gets dirty. Investigate in this order: media depth, wind exposure, air mixer.
Clean glass with white vinegar and water or mild soap, rinse, and dry it fully before it goes back. Soot collecting on a wide table rail rather than at the burner is often geometry; What Size Fire Table Do I Need? explains how lip width changes where combustion products land.
Why does the wind keep blowing my fire pit out?
An open decorative burner has a low, wide flame and nothing shielding it. A gust can lift the flame off the ports long enough for a flame-sensing system to drop out and close the gas valve. That is the safety system working, not failing.
The fix is a tempered glass wind guard sized to your pan. It steadies the flame, cuts soot around the rim, and usually makes the fire usable on evenings when it was not. We stock them in wind guards. Match Lit vs Electronic Ignition explains why an electronic unit shuts down in wind where a match lit burner just flickers — and replacing the batteries in those modules is a homeowner job.
Relocating the pit works too, as long as you keep the manufacturer's clearances; see Fire Pit Clearance Requirements.
Which flame problems can you fix, and which need a licensed technician?
The line is not a soft one. Anything above the burner face is maintenance. Anything involving the gas line, orifice, regulator or valve is gas work, governed by the National Fuel Gas Code (ANSI Z223.1 / NFPA 54) and local amendments, and it belongs to a licensed professional.
| Symptom | Mechanism | Likely cause | Who fixes it |
|---|---|---|---|
| Yellow flame, no soot | Low primary air by design | Nothing wrong | Nobody |
| Yellow flame with heavy soot | Incomplete combustion | Media too deep over the ports | Owner — remove media |
| Yellow flame with heavy soot, media already correct | Incomplete combustion | Blocked or missing air mixer | Technician |
| Low flame everywhere | Insufficient pressure or volume | Empty or cold propane tank | Owner — refill, check level |
| Low flame everywhere, tank full | Insufficient pressure or volume | Undersized line, long run, failing regulator | Technician |
| Flame on part of the burner | Obstructed gas path | Debris, webs or media in ports | Owner — brush and clear |
| Flame on part of the burner | Gas pooling to one side | Pan out of level; standing water | Owner — level, clear the drain |
| Flame surging on a still night | Restricted flow | Excess flow valve partially tripped | Owner — reset by opening slowly |
| Flame surging after a slow reset | Unstable regulation | Failing regulator | Technician |
| Flame far too high, roaring | Overfiring | Wrong orifice for the fuel | Technician — shut off first |
| Flame blows out in wind | Flame lift, sensor dropout | No wind protection | Owner — fit a wind guard |
| Any gas odor | Leak | Fitting, hose or valve | Technician — evacuate, call from outside |
If the burner is pitted, warped or has ports corroded open, replace it rather than nursing it. Our burner collection covers the common pan and drop-in formats, and the complete fire pit buying guide helps if you are weighing repair against replacement.
Fix the flame, not the whole fire pit
Wind guards, replacement burners, fresh fire glass and burner components ship free. Most flame complaints end with one of these.
Shop wind guards Shop burnersFire pit flame FAQs
Is a yellow flame on a propane fire pit dangerous?
Not by itself. Decorative propane burners are built to produce a yellow, wood-fire-like flame, and yellow alone is not a defect. What matters is whether it deposits soot quickly, drops black flakes or smells strongly. Those point to incomplete combustion, and the first thing to check is media depth over the ports.
Should my gas fire pit flame be blue?
No. A blue flame means high primary air, which is what a furnace or kitchen range is built for. A fire pit burner runs with little primary air so the carbon glows yellow. If yours suddenly burns short and blue where it was tall and yellow, an air mixer is set too far open and a technician should adjust it.
Why did my flame get lower after I added more fire glass?
Because you buried the ports. Gas has to work its way out through the media, and every extra inch restricts it. American Fyre Designs allows 1–2 inches over the burner; The Outdoor Plus allows no more than 1 inch. Rake back until the burner is just hidden and the flame returns.
How do I know if my gas line is too small for my fire pit?
Light the fire pit, then have someone start your furnace, water heater or dryer. If the flame visibly drops, the line or meter cannot carry the combined load. Compare the burner's rated BTU input and the run length against sizing tables, or have a licensed plumber do it. Undersized line is the most common cause of a permanently weak flame.
Can I clean the burner ports on my fire pit myself?
Yes. With the gas off and the burner cool, remove the media, brush the burner face with a soft brass brush, and clear blocked ports with a thin wire. Never drill or enlarge a port — that changes the flow the burner was certified for. Anything involving the orifice or gas line is technician work.
Why is my propane fire pit flame low only when it is cold outside?
Liquid propane has to vaporize inside the tank to feed the burner, and vaporization slows sharply as temperature drops. A small cylinder feeding a high-output burner on a cold night cannot keep up, so the flame sags. A larger tank, a fuller one, or a permanent natural gas line all solve it.
Is soot on fire glass normal?
On propane, a light film after a season is normal and only needs cleaning with white vinegar and water or mild soap. It is a fault when soot appears within an hour of lighting, black flakes drift off the fire, or nearby siding gets dirty. Check media depth first, then wind exposure, then the air mixer.
My fire pit flame is much bigger than it used to be. What should I do?
Shut off the gas and leave it off. A flame that suddenly runs far higher than normal and lifts off the ports means the appliance is overfiring, most often because a natural gas orifice is feeding propane after a conversion or reassembly. That is a fire and carbon monoxide hazard, and it requires a licensed gas technician under ANSI Z223.1 / NFPA 54.
Will a wind guard fix an uneven flame?
Only if wind is the cause. A tempered glass wind guard stops gusts from lifting and distorting the flame and noticeably reduces soot around the rim. It will not fix blocked ports, a pan that is out of level, standing water, or a burner starved by an undersized gas line. Diagnose on a still evening first.
My fire pit lights but goes out after a minute — is that the same problem?
No — that is a flame-sensing issue, not a combustion quality issue. A thermocouple or thermopile that is not being heated properly closes the gas valve as a safety measure. Our guide to a gas fire pit that won't light walks through those causes in order of likelihood.
Sources and accuracy note. Supply pressures (7" WC natural gas, 11" WC propane, ±1") are consistent across the manufacturer manuals we work from. Media depth figures come from American Fyre Designs and The Outdoor Plus installation literature and from Celestial Fire Glass installation guidance. Solus Decor instructs installers to build lava rock to the underside of the burner but publishes no inch figure, and we have not substituted one. Heating values (about 2,500 BTU per cubic foot for propane against 1,000 for natural gas) and the orifice-to-specific-gravity relationship follow standard gas-trade reference material. No figure here is estimated.
All gas piping, orifice, regulator, valve and fuel-conversion work must be performed by a licensed gas professional under the National Fuel Gas Code (ANSI Z223.1 / NFPA 54) and local amendments. If you smell gas: do not operate switches, shut off the supply only if you can do so safely, leave the area, and call your gas supplier or the fire department from outside.