I’m baffled by this whole Crisco/shortening candle-in-contraptions meme circulating around. You’ve got folks shoving these things in everything from copper pots to elaborate sand enclosures, claiming superior heat output and somehow making a case for off-grid energy.
Let’s unpack the physics, because frankly, it doesn’t add up:
Combustion 101: A candle (or our Crisco-fied iteration) works by burning the fuel source (fat in this case), releasing heat and light through a chemical reaction with oxygen. The material surrounding it doesn’t inherently influence this combustion process. Copper, terracotta, or sand won’t magically accelerate the burning rate or somehow trap more heat.
Radiation & Conduction: Sure, these materials might hold and radiate a BIT more heat absorbed from the flame compared to open air. But the difference is negligible. Convection (hot air rising) is the primary heat transfer mechanism, and the enclosure doesn’t significantly enhance it.
Scaling Up Fallacy: If this contraption truly held the key to efficient off-grid heating, wouldn’t we be ditching fuel oil and natural gas entirely? Imagine a skyscraper-sized Crisco candle in a cosmic copper pot - it wouldn’t magically solve our energy needs. The heat output wouldn’t scale proportionally due to limitations in combustion itself.
In short – why are people so fascinated with this? A simple test will show that it is not more effective than a simple candle, yet people seem to be continually fascinated by it.
It’s not that there is superior heat output, it’s that there is superior heat collection and observation.
Not familiar with the meme directly, taking your attached picture example I can guess why they think it’s better:
It’s trapped closer to them.
Heat, that you recognize exists but usually rises out of reach of an uncapped candle, to the ceiling, is now trapped near the observation area. The pot is trapping it and radiating it much closer to the person thinking they’ve just solved the universe.
It’s observable. Like people who don’t understand the need for vaccines because they’ve never personally seen the disease the vaccine helped beat down, a majority of people struggle to grasp theory, and direct observation is all they understand.
Yeah. The effects of convection from an uncapped candle will spread the heat to the room and ceiling much faster than when trapped. The pot absorbing the heat traps it and changes the heat transfer to radiative heating which will csuse a lower convective heat transfer coefficient when heating the air around it.
I dont think you’ve ever been really cold if you dont recognize the difference in utility between “heat up my whole room a very little amount” and “heat up something i can feel.”
To explain it simply: having heat trapped locally can help get heat into the human, which is far more important than putting heat into the air.
Radiant heat is the way.
The reason people are fascinated by this is because many people are deeply stupid, and willingly so. Between lacking education and not wanting to learn anything, you get people who think candles can be magically magnified by pots.
The first time I saw this was right after the Texas ice storm and power grid failure a few years ago. A lot of people were suddenly stuck in their now unheated homes trying to get by with what they had on hand. That’s when people found out that containing most of the heat from a candle is better than nothing.
Word spread because most people had time to kill and the stuff to try it. If you are careful about it you could warm cold hands or get a mild radiation effect if you’re close to it.
But yeah it’s not going to heat a room to any comfortable level on it’s own. And you probably don’t need the $100+ ones they sell on Etsy.
I remember the Modern Rogue (based in Austin, Texas) did an episode on it.
What? You need to give us context before you criticize something. I have no clue what you’re on about.
Yeah, what is this setup supposed to do? More light? Slower burning up of the candle? Some kind of cheap camping stove?
It’s supposed to be a space heater. The idea is candles do produce quite a bit of heat but in a cold room the heat of a few candles will rise in narrow columns to the ceiling where it will be basically be useless. Put a terra cotta pot over it and it will catch that heat inside it and start functioning as a radiant heater, allowing people in the room to enjoy the heat from some candles.
If you heat the room with a candle, you probably won’t notice the difference. Most of the heat will likely rise to the ceiling leaving you still mostly pretty cold, even if the room is 52.4 degrees rather than 52.2. Trying to directly warm yourself with a candle doesn’t really work either; the “habitable zone” of a bonfire is pretty big, you can be several feet from the flames and feel comfortably warm. A candle is so small that the distance between “can’t feel any heat at all” and “first degree burn” is thinner than your hand.
Putting a terra cotta pot over it will warm the pot to the point it feels warm, it lets you meaningfully experience the heat of the candle. That same energy will be spread out on a large surface which will feel comfortably warm to the touch.
I saw people start to come up with these contraptions after those Texas deep freezes where an entire state was caught so thoroughly off guard by long sleeve weather that they started teaching each other how to shit in buckets.
If a Youtube video gains any attention, the idea cancer will soon follow. “Hey you might be able to improvise an emergency heater out of these things you probably have around the house” becomes “finger family pregnant frozen spiderman builds artisanal crisco emergency heater.”
You are misunderstanding the purpose of the different things you are describing. People aren’t using the Crisco candles contained in sand to generate heat. Those are extended use light sources. The use of the terracotta pots placed over a candle or other flame heat source is to capture and re-radiate the heat using the terracotta pot as a larger surface for heat to radiate off of. Larger surface area = more USEFUL heat being radiated towards the people in the room. You are mixing up the ideas here. Which could work if you actually had a useful arrangement for the pot over the Crisco candle.
This isn’t my picture, which is the whole point. People are making these bizarre contraptions without even a theory of what they would do.
It’s a troll post that makes the rounds because it sounds intriguing and plausible while not being super dangerous. People will try it and realize it doesn’t work, then feel too stupid to post about it not working.
Like plugging a power strip into itself
This looks a lot like the cheap heater design for homeless people that’s been going around. That one uses ethanol and copper tubing instead of fat and a wick
I used this trick a few years back during a cold snap when my furnace wasnt working. It did genuinely seem to increase the temp of my room by around ~10 Fahrenheit over an hour or so.
my understanding was capturing the hot air for a moment allowed more heat to radiate (and the pot did genuinely get to around 150 degrees according to laser thermometer) instead of the hot air rising in a narrow stream and losing its heat into the cold ceiling.
Didn’t have a fancy setup, just a spare pot balanced on three mugs over some tea candles.
It works subjectively but is meaningless objectively.
The pot/sand/whatever is a heat sink. It heats up and slowly re-releases the heat closer to the observer (you) giving the impression of more heat.
Heating something close is objectively measureable.
A pot of water boils on a stove instead of standing next to a stove despite the stove releasing the same heat.
