Short answer: an ethanol fireplace flame can be nearly invisible, and it is hardest to see at exactly the moments people make decisions about it. Anywhere Fireplace, a maker of ethanol fireplaces, says on its safety page that when first lit, the flame “may be nearly invisible,” and that “the same happens just before fuel runs out.” Health Canada says alcohol-based fuels burn in a way that makes flames difficult to see, especially when little fuel is left. So you cannot judge whether the fire is out by looking. You confirm it by extinguishing it deliberately and letting the burner cool.
This matters because an invisible flame is not a curiosity. It is the first link in the refueling burns that the U.S. Consumer Product Safety Commission (CPSC) and Health Canada have both warned about, and it is a hazard to any child, pet or adult who reaches toward a burner that looks cold.
Why an ethanol fireplace invisible flame happens
A wood fire, a candle and a yellow gas flame are easy to see because they glow. Much of that glow comes from tiny particles of soot heated inside the flame. Alcohol fuels burn with far less of that soot, so much of the flame gives off very little visible light. Sellers market this as “clean burning.” The same property is what makes the flame hard to spot.
The regulators do not go into the chemistry, but they are clear on the outcome:
- Health Canada, in its public advisory of December 21, 2023 (read September 28, 2026): “Alcohol-based liquids will burn in a way that makes flames difficult to see, especially when a low amount of the liquid is left in the firepot.”
- The CPSC, in its December 19, 2024 consumer alert on liquid-burning fire pits and again in its May 7, 2026 warning on Northlight Bio Ethanol Portable Tabletop Fireplaces: “A small flame in the fire pit can be hard to see.”
The moments the flame hides
This is the part most product pages skip. The flame is not equally visible all evening. It hides at predictable points:
| Moment | What the sources say | Why it is dangerous |
|---|---|---|
| Just after lighting | Anywhere Fireplace says the flame “may be nearly invisible” when first lit | Someone may try to relight a burner that is already burning, or add fuel to “get it going” |
| Running low on fuel | Health Canada says flames are hardest to see when little fuel is left; Anywhere Fireplace says the flame is nearly invisible just before fuel runs out | This is when people decide it has gone out and reach for the bottle |
| After it seems to go out | The CPSC warns a small flame can be hard to see; Anywhere Fireplace warns against refilling while the unit is hot | The burner is touched, moved or refueled while still burning or hot |
Put the first two rows together and the danger becomes obvious. The two moments when the flame is least visible are the two moments when someone is most likely to be leaning over the burner with fuel in hand: at the start, and at the end. A bright room makes a faint flame harder still to pick out, which is worth remembering when an ethanol burner is lit in daylight or under strong lamps.
How an invisible flame turns into a burn
The CPSC and Health Canada both describe flame jetting: fuel poured into a burner that is still lit or still hot ignites, the flame travels up the stream, and burning fuel is thrown out onto the person pouring and anyone nearby. The CPSC says these fuels burn at over 1,600°F and can cause third degree burns in less than one second. Health Canada has recorded severe burn injuries in Canada from this pattern.
An invisible flame is what makes that sequence possible. Nobody knowingly pours alcohol onto a fire. People pour it onto a burner they believe is out. “I could not see it” is how most of these stories begin.
The invisible flame is also a contact hazard. A hand passed over a burner to “check” it, a child reaching toward the glass, a sleeve brushing across the top, a pet’s tail: none of those gets the warning a visible fire gives.
How to know it is out: confirm, do not look
Because sight fails, the only reliable approach is to make the fire go out on purpose and then wait. The sources line up on this.
- Extinguish it deliberately. Health Canada says to “use a snuffer, or something similar, to be sure the fire is out.” Use the snuffer or lid supplied with your unit and follow its manual.
- Leave the snuffer in place. Anywhere Fireplace’s safety information (read September 28, 2026) advises double checking “that no flame is present before refilling by closing lid or placing snuffer lid on top of fuel reservoir for at least one minute.” That is one maker’s instruction for its own products; your own manual’s instruction is the one that applies to your unit.
- Let the burner cool. The same page says, “NEVER REFILL THE FUEL RESERVOIR WHILE THE FLAME IS BURNING OR UNIT IS HOT,” and sets its own cooling period before adding fuel. Health Canada says to make sure the firepot has cooled before refueling. Cooling times are set per product, so use the one in your manual.
- Only then bring the fuel near. Anywhere Fireplace puts it in capitals: “NEVER OPEN FUEL BOTTLE NEAR OPEN FLAME. A DANGEROUS FIRE FLASH COULD RESULT.”
What is missing from that list is just as important. There is no step that says “look closely,” “hold your hand over it,” or “wait until it looks out.” None of those is a test.
Why a snuffer beats letting it burn out
Many owners let the fuel run dry rather than snuffing the flame. That feels safer, because nobody has to go near the fire. It actually creates the longest stretch of low, hard-to-see flame, which is the stage both Health Canada and Anywhere Fireplace single out. A burn that ends with the snuffer ends at a known moment. A burn that is allowed to die ends whenever it happens to, and nobody can see when that is.
There is an indoor air side to the end of a burn too. As reported by AirQualityNews on March 20, 2026, a University of Aveiro study found that particle levels spiked dramatically when bioethanol flames were extinguished. That is a reason to keep ventilating after the fire is out, as your manual directs, not a reason to let it burn on.
Children, pets and guests
Adults who own an ethanol burner learn its habits. Children, pets and visitors do not. Anywhere Fireplace says fuel and fireplace should only be handled by adults and warns: “DO NOT allow children or pets near fireplace when burning.” With a flame that can be nearly invisible, “burning” has to include every moment until the snuffer has done its work and the unit has cooled.
The household questions in our household test for who should not use a ventless fireplace were written for vent-free gas units, but the logic carries over. A home with toddlers, a curious dog, or a family member who cannot move away quickly has more to lose from a flame that gives no visual warning.
The combustion risk you also cannot see
An invisible flame is still a real flame burning fuel in the room, with no flue to carry its exhaust away. Germany’s Fraunhofer WKI listed carbon monoxide among the products of incomplete ethanol combustion in its 2014 research release, and carbon monoxide is colorless and odorless. Nothing about an ethanol flame warns you when CO is building up, and on vent-free gas units the oxygen depletion sensor responds to falling oxygen, not to carbon monoxide. We treat a working CO alarm in the home as a condition of using any unvented flame; our explainer on ventless fireplace carbon monoxide covers how incomplete combustion produces it.
If you want the look without the hidden flame
The things that make an ethanol flame risky, an open flame, a liquid fuel and a burner that cannot be judged by eye, all come with the product. If what you want is the look of a fire, an electric unit removes every one of them. Our comparison of ventless gas vs electric fireplaces explains the trade-off when nothing burns at all.
Frequently asked questions
Why can’t I see the flame on my ethanol fireplace?
Alcohol fuels burn with much less of the glowing soot that makes wood or candle flames visible. Health Canada says alcohol-based liquids burn in a way that makes flames difficult to see, especially when little fuel is left, and Anywhere Fireplace says the flame may be nearly invisible when first lit and just before the fuel runs out.
How do I know if my ethanol fireplace is really out?
Do not rely on looking. Put the flame out deliberately with the snuffer or lid that came with the unit, leave it in place as your manual directs, and let the burner cool before touching it or adding fuel. Health Canada recommends a snuffer “to be sure the fire is out.”
Is it safer to let an ethanol fireplace burn out on its own?
Not necessarily. Letting the fuel run dry produces a long stage of low flame, which is when both Health Canada and at least one manufacturer say the flame is hardest to see. Snuffing it ends the burn at a moment you control.
Can an ethanol flame burn someone who cannot see it?
Yes. The CPSC says these fuels burn at over 1,600°F and can cause third degree burns in less than one second, and that a small flame can be hard to see. Children, pets and guests are most at risk because they do not know the burner is lit.
Does an invisible flame still produce carbon monoxide?
It is still burning fuel, so it still produces combustion products. Fraunhofer WKI lists carbon monoxide among the products of incomplete ethanol combustion. Keep a working CO alarm in the home whenever any unvented flame is used.